Universe Today - 10 new stories for 2016/07/05



10 new stories for 2016/07/05 Messier 17 (M17) – the Omega Nebula Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Messier 17 nebula – aka. The Omega Nebula (and a few other names). In the 18th century, while searching the night sky for comets, French astronomer Charles Messier began noticing a series of "nebulous objects" in the night sky. Hoping to ensure that other astronomers did not make the same mistake, he began compiling a list of these objects,. Known to posterity as the Messier Catalog, this list has come to be one of the most important milestones in the research of Deep Sky objects. One of these is the star-forming nebula known as Messier 17 - or as it's more famously known, the Omega Nebula (or Swan Nebula, Checkmark Nebula, and Horseshoe Nebula). Located in the Sagittarius constellation, this beautiful nebula is considered one of the brightest and most massive star-forming regions in our galaxy. Description: From its position in space some 5,000 to 6,000 light years from Earth, the "Omega" nebula occupies a region as large as 40 light years across, with its brightest porition covering a 15 light year expanse. Like many nebulae, this giant cosmic cloud of interstellar matter is a starforming region in the Sagittarius or Sagittarius-Carina arm of our Milky Way galaxy. What you see is the hot hydrogen gas that is illuminated when its particles are excited by the hottest of the stars that have just formed within the nebula. Also, some of the light is being reflected by the nebula's own dust. These remain hidden by dark obscuring material, and we know their presence only through the detection of their infrared radiation. In an study titled "Interstellar Weather Vanes: GLIMPSE Mid-Infrared Stellar-Wind Bowshocks in M17 and RCW49", astronomer Matthew S. Povich (et al.) of the University of Wisconsin-Madison said of M17: "We report the discovery of six infrared stellar-wind bowshocks in the Galactic massive star formation regions M17 and RCW49 from Spitzer GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) images. The InfraRed Array Camera (IRAC) on the Spitzer Space Telescope clearly resolves the arc-shaped emission produced by the bowshocks. We use the stellar SEDs to estimate the spectral types of the three newly-identified O stars in RCW49 and one previously undiscovered O star in M17. One of the bowshocks in RCW49 reveals the presence of a large-scale flow of gas escaping the HII region. Radiation-transfer modeling of the steep rise in the SED of this bowshock toward longer mid-infrared wavelengths indicates that the emission is coming principally from dust heated by the star driving the shock. The other 5 bowshocks occur where the stellar winds of O stars sweep up dust in the expanding HII regions." Is Messier 17 still actively producing stars? You bet. Even protostars have been discovered hiding in its folds. As M. Nielbock (et al), wrote in 2008: "For the first time, we resolve the elongated central infrared emission of the large accretion disk in M 17 into a point-source and a jet-like feature that extends to the northeast. We regard the unresolved emission as to originate from an accreting intermediate to high-mass protostar. In addition, our images reveal a weak and curved southwestern lobe whose morphology resembles that of the previously detected northeastern one. We interpret these lobes as the working surfaces of a recently detected jet interacting with the ambient medium at a distance of 1700 AU from the disk centre. The accreting protostar is embedded inside a circumstellar disk and an envelope causing a visual extinction. This and its K-band magnitude argue in favour of an intermediate to high-mass object, equivalent to a spectral type of at least B4. For a main-sequence star, this would correspond to a stellar mass of 4 M." How many new stars lay hidden inside? Far more than the famous Orion nebula may contain. So says a 2013 study produced by L. Eisa (et al): "The complex resembles the Orion Nebula/KL region seen nearly edge-on: the bowl-shaped ionization blister is eroding the edge of the clumpy molecular cloud and triggering massive star formation, as evidenced by an ultra-compact HII region and luminous protostars. Only the most massive members of the young NGC 6618 stellar cluster exciting the nebula have been characterized, due to the comparatively high extinction. Near-infrared imagery and spectroscopy reveal an embedded cluster of about 100 stars earlier than B9. These studies did not cover the entire cluster, so even more early stars may be present. This is substantially richer than the Orion Nebula Cluster which has only 8 stars between O6 and B9." History of Observation: The Omega Nebula was first discovered by Philippe Loys de Cheseaux and is just one of the six nebulae in his documents. As he wrote of his discovery: "Finally, another nebula, which has never been observed. It is of a completely different shape than the others: It has perfectly the form of a ray, or of the tail of a comet, of 7' length and 2' broadth; its sides are exactly parallel and rather well terminated, as are its two ends. Its middle is whiter than the border." Because De Cheseaux's work wasn't widely read, Charles Messier independently rediscovered it on June 3, 1764 and cataloged it in his own way: "In the same night, I have discovered at little distance of the cluster of stars of which I just have told, a train of light of five or six minutes of arc in extension, in the shape of a spindle, and in almost the same as that in the girdle of Andromeda; but of a very faint light, not containing any star; one can see two of them nearby which are telescopic and placed parallel to the Equator: in a good sky one perceives very well that nebula with an ordinary refractor of 3 feet and a half. I have determined its position in right ascension of 271d 45' 48", and its declination of 16d 14' 44" south." By historical accounts, it was Sir William Herschel who may have truly had a little bit of insight on what this object might one day mean when he observed it on his own and reported: "1783, July 31. A very singular nebula; it seems to be the link to join the nebula in Orion to others, for this is not without a possibility of being stars. I think a great deal more of light and a much higher power would be of service. 1784, June 22 (Sw. 231). A wonderful nebula. Very much extended, with a hook on the preceding [Western] side; the nebulosity of the milky kind; several stars visible in it, but they seem to have no connection with the nebula, which is far more distant. I saw it only through short intervals of flying clouds and haziness; but the extent of the light including the hook is above 10'. I suspect besides, that on the following [Eastern] side it goes on much farther and diffuses itself towards the north and south. It is not of equal brightness throughout and has one or more places where the milky nebulosity seems to degenerate into the resolvable [mottled] kind; such a one is that just following the hook towards the north. Should this be confirmed on a very fine night, it would bring on the step between these two nebulosities which is at present wanting, and would lead us to surmise that this nebula is a stupendous stratum of immensely distant fixed stars, some of whose branches come near enough to us to be visible as a resolvable nebulosity, while the rest runs on to so great a distance as only to appear under the milky form." So where did the name "Omega Nebula" come from? That credit goes to John Herschel, who stated in his observing notes: "The figure of this nebula is nearly that of the Greek capital Omega, somewhat distorted and very unequally bright. It is remarkable that this is the form usually attributed to the great nebula in Orion, though in that nebula I confess I can discern no resemblence whatever to the Greek letter. Messier perceived only the bright preceding branch of the nebula now in question, without any of the attached convolutions which were first noticed by my Father. The chief peculiarities which I have observed in it are, 1st, the resolvable knot in the following portion of the bright branch, which is in a considerable degree insulated from the surrounding nebula; strongly suggesting the idea of an absorption of nebulous matter; and 2ndly, the much feebler and smaller knot in the north preceding end of the same branch, where the nebula makes a sudden bend at an acute angle. With a view to a more exact representation of this curious nebula, I have at different times taken micrometrical measures of the relative places of the stars in and near it, by which, when laid down on the chart, its limits may be traced and identified, as I hope soon to have better opportunity to do than its low situation in this latitudes will permit." Locating Messier 17: Because M17 is both large and quite bright, its distinctive "2" shape isn't hard to make out in optics of any size. For binoculars and image correct finderscopes, try starting with the constellation of Aquila and begin tracing the stars down the eagle's back to Lambda. When you reach that point, continue to extend the line through to Alpha Scuti, then southwards towards Gamma Scuti. M16 is slightly more than 2 degrees (about a fingerwidth) southwest of this star. If you are in a dark sky location, you can also identify it easily in binoculars by starting at the M24 "Star Cloud", north of Lambda Sagittari (the teapot lid star), and simply scanning north. This nebula is bright enough to even cut through moderately light polluted skies with ease, but don't expect to see it when the Moon is nearby. You'll enjoy the rich starfields combined with an interesting nebula in binoculars, while telescopes will easily begin resolving the interior stars. And here are the quick facts on M17 for your convenience: Object Name: Messier 17 Alternative Designations: M17, NGC 6618, Omega, Swan, Horseshoe, or Lobster Nebula Object Type: Open Star Cluster with Emission Nebula Constellation: Sagittarius Right Ascension: 18 : 20.8 (h:m) Declination: -16 : 11 (deg:m) Distance: 5.0 (kly) Visual Brightness: 6.0 (mag) Apparent Dimension: 11.0 (arc min) And be sure to enjoy this video from the European Southern Observatory (ESO) that shows this nebula in all its glory: https://youtu.be/YE5YEVU65pA We have written many interesting articles about Messier Objects here at Universe Today. Here's Tammy Plotner's Introduction to the Messier Objects, , M1 – The Crab Nebula, M8 – The Lagoon Nebula, and David Dickison's articles on the 2013 and 2014 Messier Marathons. Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database. The post Messier 17 (M17) – the Omega Nebula appeared first on Universe Today.        • Email to a friend • View comments • Track comments •   Juno Snaps Final View of Jovian System Ahead of 'Independence Day' Orbital Insertion Fireworks Tonight – Watch Live After a nearly 5 year odyssey across the solar system, NASA's solar powered Juno orbiter is all set to ignite its main engine late tonight and set off a powerful charge of do-or-die fireworks on America's 'Independence Day' required to place the probe into orbit around Jupiter - the 'King of the Planets.' To achieve orbit, Juno must will perform a suspenseful maneuver known as 'Jupiter Orbit Insertion' or JOI tonight, Monday, July 4, upon which the entire mission and its fundamental science hinges. There are no second chances! You can be part of all the excitement and tension building up to and during that moment, which is just hours away - and experience the 'Joy of JOI' by tuning into NASA TV tonight! Watch the live webcast on NASA TV featuring the top scientists and NASA officials starting at 10:30 p.m. EDT (7:30 p.m. PST, 0230 GMT) - direct from NASA's Jet Propulsion Laboratory: https://www.nasa.gov/nasatv And for a breathtaking warm-up act, Juno's on board public outreach JunoCam camera snapped a final gorgeous view of the Jovian system showing Jupiter and its four largest moons, dancing around the largest planet in our solar system. The newly released color image was taken on June 29, 2016, at a distance of 3.3 million miles (5.3 million kilometers) from Jupiter - just before the probe went into autopilot mode. It shows a dramatic view of the clouds bands of Jupiter, dominating a spectacular scene that includes the giant planet's four largest moons -- Io, Europa, Ganymede and Callisto. NASA also released this new time-lapse JunoCam movie today: https://youtu.be/kjfQCTat-8s Video caption: Juno's Approach to Jupiter: After nearly five years traveling through space to its destination, NASA's Juno spacecraft will arrive in orbit around Jupiter on July 4, 2016. This video shows a peek of what the spacecraft saw as it closed in on its destination. Credits: NASA/JPL-Caltech/MSSS The spacecraft is approaching Jupiter over its north pole, affording an unprecedented perspective on the Jovian system - "which looks like a mini solar system," said Juno Principal Investigator and chief scientist Scott Bolton, from the Southwest Research Institute (SwRI) in San Antonio, Tx, at today's media briefing at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "The deep interior of Jupiter is nearly unknown. That's what we are trying to learn about." The 35-minute-long main engine burn is preprogrammed to start at 11:18 p.m. EDT (8:18 p.m. PST, 0318 GMT). It is scheduled to last until approximately 11:53 p.m. (8:53 p.m. PST, 0353 GMT). All of the science instruments were turned off on June 30 to keep the focus on the nail-biting insertion maneuver and preserve battery power, said Bolton. Solar powered Juno is pointed away from the sun during the engine firing. JOI is required to slow the spacecraft so it can be captured into the gas giant's orbit as it closes in over the north pole. Initially the spacecraft will enter a long, looping polar orbit lasting about 53 days. That highly elliptical orbit will quickly be trimmed to 14 days for the science orbits. The orbits are designed to minimize contact with Jupiter's extremely intense radiation belts. The science instruments are shielded inside a ½ thick vault built of Titanium to protect them from the utterly deadly radiation - of some 20,000,000 rads. Juno is the fastest spacecraft ever to arrive at Jupiter and is moving at over 165,000 mph relative to Earth and 130,000 mph relative to Jupiter. After a five-year and 2.8 Billion kilometer (1.7 Billion mile) outbound trek to the Jovian system and the largest planet in our solar system and an intervening Earth flyby speed boost, the moment of truth for Juno is now inexorably at hand. Signals traveling at the speed of light take 48 minutes to reach Earth, said Rick Nybakken, Juno project manager from NASA's Jet Propulsion Laboratory, at the media briefing. So the main engine burn, which is fully automated, will already be over for some 13 minutes before the first indications of the outcome reach Earth via a series of Doppler shifts and tones. It is about 540 million miles (869 million kilometers) from Earth. "By the time the burn is complete, we won't even hear about it until 13 minutes later." "The engine burn will slow Juno by 542 meters/second (1,212 mph) and is fully automated as it approaches over Jupiter's North Pole," explained Nybakken. "The long five year cruise enabled us to really learn about the spacecraft and how it operates." As it travels through space, the basketball court sized Juno is spinning like a windmill with its 3 giant solar arrays. "Juno is also the farthest mission to rely on solar power. The solar panels are 60 square meters in size. And although they provide only 1/25th the power at Earth, they still provide over 500 watts of power at Jupiter." The protective cover that shields Juno's main engine from micrometeorites and interstellar dust was opened on June 20. During a 20 month long science mission - entailing 37 orbits lasting 14 days each – the probe will plunge to within about 3000 miles of the turbulent cloud tops and collect unprecedented new data that will unveil the hidden inner secrets of Jupiter's origin and evolution. "Jupiter is the Rosetta Stone of our solar system," says Bolton. "It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary — to interpret what Jupiter has to say." During the orbits, Juno will probe beneath the obscuring cloud cover of Jupiter and study its auroras to learn more about the planet's origins, structure, atmosphere and magnetosphere. The $1.1 Billion Juno was launched on Aug. 5, 2011 from Cape Canaveral, Florida atop the most powerful version of the Atlas V rocket augmented by 5 solid rocket boosters and built by United Launch Alliance (ULA). That same Atlas V 551 version just launched MUOS-5 for the US Navy on June 24. The Juno spacecraft was built by prime contractor Lockheed Martin in Denver. Along the way Juno made a return trip to Earth on Oct. 9, 2013 for a flyby gravity assist speed boost that enabled the trek to Jupiter. The flyby provided 70% of the velocity compared to the Atlas V launch, said Nybakken. During the Earth flyby (EFB), the science team observed Earth using most of Juno's nine science instruments since the slingshot also serves as an important dress rehearsal and key test of the spacecraft's instruments, systems and flight operations teams. Juno also went into safe mode - something the team must avoid during JOI. What lessons were learned from the safe mode event and applied to JOI, I asked? "We had the battery at 50% state of charge during the EFB and didn't accurately predict the sag on the battery when we went into eclipse. We now have a validated high fidelity power model which would have predicted that sag and we would have increased the battery voltage," Nybakken told Universe Today "It will not happen at JOI as we don't go into eclipse and are at 100% SOC. Plus the instruments are off which increases our power margins." Junocam also took some striking images of Earth as it sped over Argentina, South America and the South Atlantic Ocean and came within 347 miles (560 kilometers) of the surface. For example the dazzling portrait of our Home Planet high over the South American coastline and the Atlantic Ocean. For a hint of what's to come, see our colorized Junocam mosaic of land, sea and swirling clouds, created by Ken Kremer and Marco Di Lorenzo The last NASA spacecraft to orbit Jupiter was Galileo in 1995. It explored the Jovian system until 2003. Stay tuned here for Ken's continuing Earth and Planetary science and human spaceflight news. Ken Kremer The post Juno Snaps Final View of Jovian System Ahead of 'Independence Day' Orbital Insertion Fireworks Tonight – Watch Live appeared first on Universe Today.        • Email to a friend • View comments • Track comments •   Stars Are The Universe's Neat Freaks Imagine, if you will, that the Universe was once a much dirtier place than it is today. Imagine also that what we see around us, a relatively clean and unobscured Universe, is the result of billions of years of stars behaving like giant celestial Roombas, cleaning up the space around them in preparation for our arrival. According to a set of recently published catalogues, which detail the latest findings from the ESA's Herschel Space Observatory, this description is actually quite fitting. These catalogues represents the work of an international team of over 100 astronomers who have spent the past seven years analyzing the infrared images taken by the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS). Presented earlier this week at the National Astronomy Meeting in Nottingham, this catalogue revealed that as early as 1 billion years ago, the Universe looked much different than it does today. In order to put this research into context, it is important to understand the important of infrared astronomy. Prior to the deployment of missions like Herschel (which was launched in 2009), astronomers were unable to see a good portion of the light emitted by stars and galaxies. With roughly half of this light being absorbed by interstellar dust grains, research into the birth and lives of galaxies was difficult. But thanks to surveys like Herschel ATLAS - as well NASA's Spitzer Space Telescope and the Wide-field Infrared Survey Explorer (WISE) - astronomers have been able to account for this missing energy. And what they have seen (especially from this latest survey) has been quite remarkable, presenting a Universe that is far denser than previously expected. Last week (Friday, June 29th), during the final day of the National Astronomy Meeting, the first of the catalogues was presented. The images they showed gave all those present a glimpse of the unseen stars and galaxies that have existed over the last 12 billion years of cosmic history. In sum,  over half-a-million far-infrared sources have been spotted by the Herschel-ATLAS survey, and what they revealed was fascinating. Many of these sources were galaxies that are nearby and similar to our own, and which are detectable using using conventional telescopes. The others were much more distant, their light taking billions of years to reach us, and were obscured by concentrations of cosmic dust. The most distant of these galaxies were roughly 12 billion light-years away, which means that they appeared as they would have 12 billion years ago. Ergo, astronomers now know that 12 billion years ago (i.e. shortly after the Big Bang)., stars and galaxies were much dustier than they are now. They further concluded that the evolution of our galaxies since shortly after the Big Bang has essentially been a major clean-up effort, as stars gradually absorbed the dust that obscured their light, thus making it the more "visible" place it is today. The data released by the survey includes several maps and additional files which were described in an article produced by Dr. Elisabetta Valiante and a research team from Cardiff University - titled "The Herschel-ATLAS Data Release 1 Paper I: Maps, Catalogues and Number Counts". As Dr. Valiante told Universe Today via email: "Gas and dust are the main components of stars: they collapse to form stars and they are ejected at the end of stars' life. The interesting thing that has been discovered thanks to the Herschel data is that the two phenomena are not in equilibrium. We knew this was true 10 billion years ago, but we expected, according to the current models, that some equilibrium was reached at more recent times. Instead, the amount of dust in galaxies 5 billion years ago was much larger than the amount we see in galaxies today: this was unexpected." Until recently, such a survey would have been impossible due to the fact that many of these infrared sources would have  been invisible to astronomers. The reason for this, which was revealed by the survey, was that these galaxies were so dusty that they would have been virtually impossible to detect with conventional optics. What's more, their light would have been gravitationally magnified by intervening galaxies. The huge size of the survey has also meant that changes that have occurred in galaxies - relatively recent in cosmic history - can be studied for the first time. For instance, the survey showed that even only one billion years in the past, a small fraction of the age of the universe, galaxies were forming stars at a faster rate and contained more dust than they do today. Dr. Nathan Bourne - from the University of Edinburgh - is the lead author of another other paper describing the catalogues. As he told Universe Today via email: "We can think of galaxies as big recycling machines. When they form, they accrete gas (mostly hydrogen and helium, with traces of lithium and a couple of other elements) from the universe around them, and they turn it into stars. As time goes on, the stars pump this gas back out into the galaxy, into the interstellar medium. Due to the nuclear processes within the stars, the gas is now enriched by heavy elements (what we call metals, though they include both metals and non-metals), and some of these form microscopic solid particles of dust, as a sort of by-product. "But there are still stars forming, and the next generations of stars recycle this interstellar material, and now that it contains heavy elements and dust, things are a bit different, and planets can also form around the new stars, from accumulations of this heavy material. So, if you look at the big picture, when the first galaxies started forming within the first billion years after the Big Bang, they began using up the gas around them, and then while they are active they fill their interstellar medium up with gas and dust, but by the end of a galaxy's lifecycle, it has used up all this gas and dust, and you could say that it has cleaned itself." The catalogues and maps of the hidden universe are a triumph for the Herschel team. Despite the fact that the last information obtained by the Herschel observatory was back in 2013, the maps and catalogues produced from its years of service have become vital to astronomers. In addition to showing the Universe's hidden energy, they are also laying the groundwork for future research. "Now we need to explain why there is dust where we did not expect to find it." said Valiante. "And to explain this, we need to change our theories about how the Universe evolves. Our data poses a challenge we have accepted, but we haven't overcome it yet!" "[W]e understand a lot more about how galaxies evolve," added Bourne, "about when most of the stars formed, what happens to the gas and dust as galaxies evolve, and how rapidly the star-forming activity in the Universe as a whole has faded in the latter half of the Universe's history. It's fair to say that this understanding comes from having a whole suite of different types of instruments studying different aspects of galaxies in complementary ways, but Herschel has certainly contributed a major part of that effort and will have a lasting legacy." The implications of these findings are also likely to have a far-reaching effect, ranging from cosmology and astronomy, to perhaps shedding some light on that tricky Fermi paradox. Could it be intelligent life that emerged billions of years ago didn't venture to other star systems because they couldn't see them? Just a thought... This data release from the H-ATLAS team was coordinated with releases made in late June from the Herschel Extragalactic Project (HELP) team and the Herschel Multi-tiered Extragalactic Survey (HerMES). H-ATLAS and HerMES are parts of the EU Research Executive Agency's HELP program, which brings together various extragalactic surveys carried out by Herschel and combines them with major surveys conducted by other observatories to give the Herschel mission a lasting legacy. Further Reading: Royal Astronomical Society, ESA The post Stars Are The Universe’s Neat Freaks appeared first on Universe Today.        • Email to a friend • View comments • Track comments •   Earth at Aphelion 2016 Having a great July 4th? The day gives us another cause to celebrate, as the Earth reaches aphelion today, or our farthest point to our host star. Aphelion is the opposite of the closest point of the year, known as perihelion. Note that the 'helion' part only applies to things in solar orbit, perigee/apogee for orbit 'round the Earth, apolune/perilune for orbit around the Moon, and so on. You'll hear the words apijove and perijove bandied about this week a bit, as NASA's Juno spacecraft enters orbit around Jupiter tonight. And there are crazier and even more obscure counterparts out there, such as peribothron and apobothron (orbiting a black hole) and apastron/periastron (orbiting a star other than our Sun). And finally, there's the one-size fits all generic periapsis and apoapsis, good for all occasions and ending pedantic arguments. In the 21st century, aphelion for the Earth can actually fall anywhere from July 2nd to the 7th. The once every four year leap day is the primary driver in this oscillation, and the exclusion of a century leap day in 2100 — the first such exclusion since 1900 — will reset things even farther astray. In 2016, the Moon reaches New on July 4th at 11:01 Universal Time (UT) just over five hours prior to aphelion, marking the start of lunation 1157. The sighting of the waxing crescent Moon also marks the end of the Muslim fasting month of Ramadan. Earth reaches aphelion at 16:24 UT today, 1.0168 AU from the Sun. This year's close occurrence of aphelion versus a New Moon won't get topped until 2054, with an aphelion versus New Moon just 5 hours 6 minutes apart. The 2016 coincidence is also the closest since the start of the 21st century. Fun fact: we're headed towards an aphelion maximum just 6,590 kilometers off of the mean on July 4th, 2019, the widest for the 21st century. Mean distance from the Sun at aphelion is 1.0167 AU (152,097,701 km). Aphelion for the Earth can range over a variation of 21,225 kilometers for the 21st century.   It's a happy circumstance that Earth reaches aphelion in our current epoch in the midst of northern hemisphere summer, and just a few weeks after the June solstice. The eccentricity of the Earth's orbit actually varies from near-circular to 0.0679 and back over the span of 413,000 years. In our current epoch, the eccentricity of our orbit is 0.017 and decreasing. Add this variation to changes in the axial tilt of our planet and orbital obliquity, and you have what are known as Milankovitch Cycles. One only has to look at Mars's wacky orbit with an eccentricity of 0.0934 to see what a difference it makes. Ironically, Mars reaches perihelion in October 29th, 2016, and will make a very close pass near next opposition pass in 2018. Want to prove it for yourself? You can indeed 'observe' aphelion. The trick is to image the solar disk using the same rig and settings... about six months apart. At aphelion, the solar disk is 31.6' across, versus 32.7' across at perihelion. This variation is slight, but you can indeed see the subtle difference side by side: Aphelion means a smaller apparent Sun, a good target for a total solar eclipse. Stick around until July 2nd, 2019 and you'll see just that, as a total solar eclipse occurs near aphelion for South America and the southern Pacific at 4 minutes and 33 seconds in central duration. This month also sees another special treat, as all classical planets enter the evening sky. More to come on that soon. For now, happy 4th of July, and merry aphelion! The post Earth at Aphelion 2016 appeared first on Universe Today.        • Email to a friend • View comments • Track comments •   The Juno Mission Ever since Galileo first observed it through a telescope in 1610, Jupiter and its system of moons have fascinated humanity. And while many spacecraft have visited the system in the past forty years, the majority of these missions were flybys. With the exception of the Galileo space probe, the visits of these spacecraft to the Jupiter system were one of several intended objectives, taking place before they made their way deeper into the Solar System. Having launched on August 5th, 2011, NASA's Juno spacecraft has a different purpose in mind. Using a suite of scientific instruments, Juno will study Jupiter's atmosphere, magnetic environment, weather patterns, and shed light on the history of its formation. In essence, it will be the first probe since the Galileo mission to orbit Jupiter, where it will spend the next two years sending information about the gas giant back to Earth. If successful, Juno will prove to be the only other long-term mission to Jupiter. However, compared to Galileo - which spent seven years in orbit around the gas giant - Juno's mission is planned to last for just two years. However, its improved suite of instruments are expected to provide a wealth of information in that time. And barring any mission extensions, its targeted impact on the surface of Jupiter will take place in February of 2018. Background: As part of the NASA's New Frontiers program, the Juno mission is one of several medium-sized missions intended to explore the various bodies of the Solar System. It is currently one of three probes that NASA is operating, or in the process of building. The other two are the New Horizons probe (which flew by Pluto in 2015) and OSIRIS-REx, which is expected to fly to asteroid 101955 Bennu in 2020 and bring samples back to Earth. During a 2003 decadal survey - titled "New Frontiers in the Solar System: An Integrated Exploration Strategy" - The National Research Council discussed destinations that would serve as the source for the first competition for the New Frontiers program. A Jupiter orbiter was identified as a scientific priority, which it was hoped would address several unanswered questions pertaining to the gas giant. These included whether or not Jupiter had a central core (the research of which would help establish how the planet was formed), the water content of Jupiter's atmosphere, how its weather systems can remain stable, and what the nature of the magnetic field and plasma surrounding Jupiter are. In 2005, Juno was selected for the New Frontiers program alongside New Horizons and OSIRIS-REx. Though it was originally intended to launch in 2009, NASA budget restrictions forced a delay until August of 2011. The probe was named in honor of the Roman goddess Juno, the wife of Jupiter (the Roman equivalent of Zeus) who was able to peer through a veil of clouds that Jupiter drew around himself. The name was previously a backronym which stood for JUpiter Near-polar Orbiter as well. https://youtu.be/SgEsf4QcR0Q Mission Profile: The Juno mission was created for the specific purpose of studying Jupiter for the sake of learning more about the formation of the Solar System. For some time, astronomers have understood that Jupiter played an important role in the development Solar System. Like the other gas giants, it was assembled during the early stages, before our Sun had the chance to absorb or blow away the light gases in the huge cloud from which they were born. As such, Jupiter's composition could tell us much about the early Solar System. Similarly, the gas giants are believed to have played a major role in the process of planet formation because their huge masses allowed them to shape the orbits of other objects - planets, asteroids and comets - in their planetary systems. However, for astronomers and planetary scientists, much still remains unknown about this massive gas giant. For instance, Jupiter's interior structure and composition, as well as what drives its magnetic field, are still the subject of theory. Because Jupiter formed at the same time as the Sun, their chemical compositions should be similar, but research has shown that Jupiter has more heavy elements than our Sun (such as carbon and nitrogen). In addition, there are some unanswered questions about when and where the planet formed. While it may have formed in its current orbit, some evidence suggests that it could have formed farther from the sun before migrating inward. All of these questions, it is hoped, are things the Juno mission will answer. Having launched on August 5th, 2011, the Juno spacecraft spent the next five years in space, and will reach Jupiter on July 4th, 2018. Once in orbit, it will spend the next two years orbiting the planet a total of 37 times from pole to pole, using its scientific instruments to probe beneath the gas giant's obscuring cloud cover. Instrumentation: The Juno spacecraft comes equipped with a scientific suite of 8 instruments that will allow it to study Jupiter's atmosphere, magnetic and gravitational field, weather patterns, its internal structure, and its formational history. They include: Gravity Science: Using radio waves and measuring them for Doppler effect, this instrument will measure the distribution of mass inside Jupiter to create a gravity map. Small variations in gravity along the orbital path of the probe will induce small changes in velocity. The principle investigators of this instrument are John Anderson of NASA's Jet Propulsion Laboratory and Luciano Iess of the Sapienza University of Rome. JunoCam: This visible light/telescope is the spacecraft's only imaging device. Intended for public outreach and education, it will provide breathtaking pictures of Jupiter and the Solar System, but will operate for only seven orbits around Jupiter (due to the effect Jupiter's radiation and magnetic field have on instruments). The PI for this instrument is Michael C. Malin, of Malin Space Science Systems Jovian Auroral Distribution Experiment (JADE): Using three energetic particle detectors, the JADE instrument will measure the angular distribution, energy, and velocity vector of low energy ions and electrons in the auroras of Jupiter. The PI is David McComas of the Southwest Research Institute (SwRI). Jovian Energetic Particle Detector Instrument (JEDI): Like JADE, JEDI will measure the angular distribution and the velocity vector of ions and electrons, but at high-energy and in the magnetosphere of Jupiter. The PI is Barry Mauk of NASA's Applied Physics Laboratory. Jovian Infrared Aural Mapper (JIRAM): Operating in the near-infrared, this spectrometer will be responsible for mapping the upper layers of Jupiter's atmosphere. By measuring the heat that is radiated outward, it will determine how water-rich clouds can float beneath the surface. It will also be able to assess the distribution of methane, water vapor, ammonia and phosphine in Jupiter's atmosphere. Angioletta Coradini of the Italian National Institute for Astrophysics is the PI on this instrument. Magnetometer: This instrument will be used to map Jupiter's magnetic field, determine the dynamics of the planet's interior and determine the three-dimensional structure of the polar magnetosphere. Jack Connemey of NASA's Goddard Space Flight Center is the instrument's PI. Microwave Radiometer: The MR instrument will perform measurements of the electromagnetic waves that pass through the Jovian atmosphere, measuring the abundance of water and ammonia in its deep layers. In so doing, it will obtain a temperature profile at various levels and determine how deep the atmospheric circulation of Jupiter is. The PI for this instrument is Mike Janssen of the JPL. Radio and Plasma Wave Sensor (RPWS): This RPWS will measure the radio and plasma spectra in Jupiter's auroral region. In the process, it will identify the regions of auroral currents that define the planet's radio emissions and accelerate its auroral particles. William Kurth of the University of Iowa is the PI. Ultraviolet Imaging Spectrograph (UVS): The UVS will record the wavelength, position and arrival time of detected ultraviolet photons, providing spectral images of the UV auroral emissions in the polar magnetosphere. G. Randall Gladstone of the SwRI is the PI. In addition to its scientific suite, the Juno spacecraft also carries a commemorative plaque dedicated to Galileo Galilei. The plaque was provided by the Italian Space Agency and depicts a portrait of Galileo, as well as script that had been composed by Galileo himself on the occasion that he observed Jupiter's four largest moons (known today as the Galilean Moons). The text, written in Italian and transcribed from Galileo's own handwriting, translates as: "On the 11th it was in this formation, and the star closest to Jupiter was half the size than the other and very close to the other so that during the previous nights all of the three observed stars looked of the same dimension and among them equally afar; so that it is evident that around Jupiter there are three moving stars invisible till this time to everyone." The spacecraft also carries three Lego figurines representing Galileo, the Roman god Jupiter and his wife Juno. The figure of Juno holds a magnifying glass as a sign of her searching for the truth, Jupiter holds a lightning bolt, and the figure of Galileo Galilei holds his famous telescope. Lego made these figurines out of aluminum (instead of the usual plastic) to ensure they would survive the extreme conditions of space flight. Launch: The Juno mission launched from Cape Canaveral Air Force Station on August 5th, 2011, atop an Atlas V rocket. After approximately 1 minute and 33 seconds, the five Solid Rocket Boosters (SRBs) reached burnout and then fell away. After 4 minutes and 26 seconds after liftoff, the Atlas V main engine cut off, followed 16 seconds later by the separation of the Centaur upper stage rocket. After a burn that lasted for 6 minutes, the Centaur was put into its initial parking orbit. It coasted for approximately 30 minutes before its engine conducted a second firing which lasted for 9 minutes, putting the spacecraft on an Earth escape trajectory. About 54 minutes after launch, the spacecraft separated from the Centaur and began to extend its solar panels. https://youtu.be/ouNiZCw4bDU A year after launch, between August and September 2012, the Juno spacecraft successfully conducted two Deep Space Maneuvers designed to correct its trajectory. The first maneuver (DSM-1) occurred on August 30th, 2012, with the main engine firing for approximately 30 minutes and altering its velocity by about 388 m/s (1396.8 km/h; 867 mph). The second maneuver (DSM-2), which had a similar duration and resulted in a similar velocity change, took place on September 14th. The two firings occurred when the probe was about 480 million km (298 million miles) from Earth, and altered the spacecraft's speed and its Jupiter-bound trajectory, setting the stage for a gravity assist from its flyby of Earth. Earth Flyby: Juno's Earth flyby took place on October 9th, 2013, after the spacecraft completed one elliptical orbit around the Sun. During its closest approach, the probe was at an altitude of about 560 kilometers (348 miles). The Earth flyby boosted Juno's velocity by 3,900 m/s (14162 km/h; 8,800 mph) and placed the spacecraft on its final flight path for Jupiter. https://youtu.be/_CzBlSXgzqI During the flyby, Juno's Magnetic Field Investigation (MAG) instrument managed to capture some low-resolution images of the Earth and Moon. These images were taken while the Juno probe was about 966,000 km (600,000 mi) away from Earth - about three times the Earth-moon separation. They were later combined by technicians at NASA's JPL to create the video shown above. The Earth flyby was also used as a rehearsal by the Juno science team to test some of the spacecraft's instruments and to practice certain procedures that will be used once the probe arrives at Jupiter. Rendezvous With Jupiter: The Juno spacecraft will reach the Jupiter system and begin procedures to establish polar orbit around the gas giant by July 4th, 2016. It's planned  orbit will be highly elliptical and will take it close to the poles - within 4,300 km (2,672 mi) - before reaching beyond the orbit of Callisto, the most distant of Jupiter's large moons (at an average distance of 1,882,700 km or 1,169,855.5 mi). https://youtu.be/UtyUEOAfRx0 This orbit will allow the spacecraft to avoid long-term contact with Jupiter's radiation belts, while still allowing it to perform close-up surveys of Jupiter's polar atmosphere, magnetosphere and gravitational field. The spacecraft will spend the next two years orbiting Jupiter a total of 37 times, with each orbit taking 14 days. Already, the probe has performed measurements of Jupiter's magnetic field. This began on June 24th when Juno crossed the bow shock just outside Jupiter's magnetosphere, followed by it's transit into the lower density of the Jovian magnetosphere on June 25. Having made the transition from an environment characterized by solar wind to one dominated by Jupiter's magnetosphere, the ship's instruments revealed some interesting information about the sudden change in particle density. End of Mission: The Juno mission is set to conclude in February of 2018, after completing 37 orbits of Jupiter. At this point, and barring any mission extensions, the probe will be de-orbited to burn up in Jupiter's outer atmosphere. As with the Galileo spacecraft, this will be as to avoid any possibility of impact and biological contamination with one of Jupiter's moons. The mission is managed by the JPL, and its principal investigator is Scott Bolton of the Southwest Research Institute. NASA's Launch Services Program, located at the Kennedy Space Center in Florida, is responsible for managing launch services for the probe. The Juno mission is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Ala. https://youtu.be/TxtLYk-7aXM As of the writing of this article, the Juno mission is one day, four hours and fifty-five minutes away from its historic arrival with Jupiter. Check out NASA's Juno mission page to get up-to-date information on the mission, and stay tuned to Universe Today for updates! We have written many interesting articles about Jupiter here at Universe today. Here's Juno Blasts off on Science Trek to Discover Jupiter's Genesis, Jupiter Bound Juno snaps Dazzling Gallery of Planet Earth Portraits, Understanding Juno's Orbit: An Interview with NASA's Scott Bolton, NASA's Juno probe Gets Gravity Speed Boost during Earth Flyby But Enters 'Safe Mode. Astronomy cast also has relevant episodes on the subject. Here's Episode 59: Jupiter, and Episode 232: Galileo Spacecraft, For more information, check out NASA's Juno mission page, and the Southwest Research Institute's Juno page. The post The Juno Mission appeared first on Universe Today.        • Email to a friend • View comments • Track comments •   NASA Approves New Horizons Extended KBO Mission, Keeps Dawn at Ceres In an 'Independence Day' gift to a slew of US planetary research scientists, NASA has granted approval to nine ongoing missions to continue for another two years this holiday weekend. The biggest news is that NASA green lighted a mission extension for the New Horizons probe to fly deeper into the Kuiper Belt and decided to keep the Dawn probe at Ceres forever, rather than dispatching it to a record breaking third main belt asteroid. And the exciting extension news comes just as the agency's Juno probe is about to ignite a do or die July 4 fireworks display to achieve orbit at Jupiter - detailed here. "Mission approved!" the researchers gleefully reported on the probes Facebook and Twitter social media pages. "Our extended mission into the #KuiperBelt has been approved. Thanks to everyone for following along & hopefully the best is yet to come. The New Horizons spacecraft will now continue on course in the Kuiper Belt towards an small object known as 2014 MU69, to carry out the most distant close encounter with a celestial object in human history. "Here's to continued success!" The spacecraft will rendezvous with the ancient rock on New Year's Day 2019. Researchers say that 2014 MU69 is considered as one of the early building blocks of the solar system and as such will be invaluable to scientists studying the origin of our solar system how it evolved. It was almost exactly one year ago on July 14, 2015 that New Horizons conducted Earth's first ever up close flyby and science reconnaissance of Pluto - the most distant planet in our solar system and the last of the nine planets to be explored. The immense volume of data gathered continues to stream back to Earth every day. "The New Horizons mission to Pluto exceeded our expectations and even today the data from the spacecraft continue to surprise," said NASA's Director of Planetary Science Jim Green at NASA HQ in Washington, D.C. "We're excited to continue onward into the dark depths of the outer solar system to a science target that wasn't even discovered when the spacecraft launched." While waiting for news on whether NASA would approve an extended mission, the New Horizons engineering and science team already ignited the main engine four times to carry out four course changes in October and November 2015, in order to preserve the option of the flyby past 2014 MU69 on Jan 1, 2019. Green noted that mission extensions into fiscal years 2017 and 2018 are not final until Congress actually passes sufficient appropriation to fund NASA's Planetary Science Division. "Final decisions on mission extensions are contingent on the outcome of the annual budget process." Tough choices were made even tougher because the Obama Administration has cut funding for the Planetary Sciences Division - some of which was restored by a bipartisan majority in Congress for what many consider NASA's 'crown jewels.' NASA's Dawn asteroid orbiter just completed its primary mission at dwarf planet Ceres on June 30, just in time for the global celebration known as Asteroid Day. "The mission exceeded all expectations originally set for its exploration of protoplanet Vesta and dwarf planet Ceres," said NASA officials. The Dawn science team had recently submitted a proposal to break out of orbit around the middle of this month in order to this conduct a flyby of the main belt asteroid Adeona. Green declined to approve the Dawn proposal, citing additional valuable science to be gathered at Ceres. The long-term monitoring of Ceres, particularly as it gets closer to perihelion – the part of its orbit with the shortest distance to the sun -- has the potential to provide more significant science discoveries than a flyby of Adeona," he said. The funding required for a multi-year mission to Adeona would be difficult in these cost constrained times. However the spacecraft is in excellent shape and the trio of science instruments are in excellent health. Dawn arrived at Ceres on March 6, 2015 and has been conducting unprecedented investigation ever since. Dawn is Earth's first probe in human history to explore any dwarf planet, the first to explore Ceres up close and the first to orbit two celestial bodies. The asteroid Vesta was Dawn's first orbital target where it conducted extensive observations of the bizarre world for over a year in 2011 and 2012. The mission is expected to last until at least later into 2016, and possibly longer, depending upon fuel reserves. Due to expert engineering and handling by the Dawn mission team, the probe unexpectedly has hydrazine maneuvering fuel leftover. Dawn will remain at its current altitude at the Low Altitude Mapping Orbit (LAMO) for the rest of its mission, and indefinitely afterward, even when no further communications are possible. Green based his decision on the mission extensions on the biannual peer review scientific assessment by the Senior Review Panel. Dawn was launched in September 2007. The other mission extensions - contingent on available resources - are: the Mars Reconnaissance Orbiter (MRO), Mars Atmosphere and Volatile EvolutioN (MAVEN), the Opportunity and Curiosity Mars rovers, the Mars Odyssey orbiter, the Lunar Reconnaissance Orbiter (LRO), and NASA's support for the European Space Agency's Mars Express mission. Stay tuned here for Ken's continuing Earth and planetary science and human spaceflight news. Ken Kremer The post NASA Approves New Horizons Extended KBO Mission, Keeps Dawn at Ceres appeared first on Universe Today.        • Email to a friend • View comments • Track comments •   The Dutch Are Going To The Moon With The Chinese One of the defining characteristics of the New Space era is partnerships. Whether it is between the private and public sector, different space agencies, or different institutions across the world, collaboration has become the cornerstone to success. Consider the recent agreement between the Netherlands Space Office (NSO) and the Chinese National Space Agency (CNSA) that was announced earlier this week. In an agreement made possible by the Memorandum of Understanding (MoU) signed in 2015 between the Netherlands and China, a Dutch-built radio antenna will travel to the Moon aboard the Chinese Chang'e 4 satellite, which is scheduled to launch in 2018. Once the lunar exploration mission reaches the Moon, it will deposit the radio antenna on the far side, where it will begin to provide scientists with fascinating new views of the Universe. The radio antenna itself is also the result of collaboration, between scientists from Radboud University, the Netherlands Institute for Radio Astronomy (ASTRON) and the small satellite company Innovative Solutions in Space (ISIS). After years of research and development, these three organizations have produced an instrument which they hope will usher in a new era of radio astronomy. Essentially, radio astronomy involves the study of celestial objects - ranging from stars and galaxies to pulsars, quasars, masers and the Cosmic Microwave Background (CMB) - at radio frequencies. Using radio antennas, radio telescopes, and radio interferometers, this method allows for the study of objects that might otherwise be invisible or hidden in other parts of the electromagnetic spectrum. One drawback of radio astronomy is the potential for interference. Since only certain wavelengths can pass through the Earth's atmosphere, and local radio wave sources can throw off readings, radio antennas are usually located in remote areas of the world. A good example of this is the Very-Long Baseline Array (VLBA) located across the US, and the Square Kilometer Array (SKA) under construction in Australia and South Africa. One other solution is to place radio antennas in space, where they will not be subject to interference or local radio sources. The antenna being produced by Radbound, ASTRON and ISIS is being delivered to the far side of the Moon for just this reason. As the latest space-based radio antenna to be deployed, it will be able to search the cosmos in ways Earth-based arrays cannot, looking for vital clues to the origins of the universe. As Heino Falke - a professor of Astroparticle Physics and Radio Astronomy at Radboud - explained in a University press release, the deployment of this radio antenna on the far side of the Moon will be an historic achievement: "Radio astronomers study the universe using radio waves, light coming from stars and planets, for example, which is not visible with the naked eye. We can receive almost all celestial radio wave frequencies here on Earth. We cannot detect radio waves below 30 MHz, however, as these are blocked by our atmosphere. It is these frequencies in particular that contain information about the early universe, which is why we want to measure them." As it stands, very little is known about this part of the electromagnetic spectrum. As a result, the Dutch radio antenna could be the first to provide information on the development of the earliest structures in the Universe. It is also the first instrument to be sent into space as part of a Chinese space mission. Alongside Heino Falcke, Marc Klein Wolt - the director of the Radboud Radio Lab - is one of the scientific advisors for the project. For years, he and Falcke have been working towards the deployment of this radio antenna, and have high hopes for the project. As Professor Wolt said about the scientific package he is helping to create: "The instrument we are developing will be a precursor to a future radio telescope in space. We will ultimately need such a facility to map the early universe and to provide information on the development of the earliest structures in it, like stars and galaxies." Together with engineers from ASTRON and ISIS, the Dutch team has accumulated a great deal of expertise from their years working on other radio astronomy projects, which includes experience working on the Low Frequency Array (LOFAR) and the development of the Square Kilometre Array, all of which is being put to work on this new project. Other tasks that this antenna will perform include monitoring space for solar storms, which are known to have a significant impact on telecommunications here on Earth. With a radio antenna on the far side of the Moon, astronomers will be able to better predict such events and prepare for them in advance. Another benefit will be the ability to measure strong radio pulses from gas giants like Jupiter and Saturn, which will help us to learn more about their rotational speed. Combined with the recent ESO efforts to map Jupiter at IR frequencies, and the data that is already arriving from the Juno mission, this data is likely to lead to some major breakthroughs in our understanding of this mysterious planet. Last, but certainly not least, the Dutch team wants to create the first map of the early Universe using low-frequency radio data. This map is expected to take shape after two years, once the Moon has completed a few full rotations around the Earth and computer analysis can be completed. It is also expected that such a map will provide scientists with additional evidence that confirms the Standard Model of Big Bang cosmology (aka. the Lambda CDM model). As with other projects currently in the works, the results are likely to be exciting and groundbreaking! Further Reading: Radbound University The post The Dutch Are Going To The Moon With The Chinese appeared first on Universe Today.        • Email to a friend • View comments • Track comments •   What is Time Dilation? One of the most interesting topics in the field of science is the concept of General Relativity. You know, this idea that strange things happen as you near the speed of light. There are strange changes to the length of things, bizarre shifting of wavelengths. And most puzzling of all, there's the concept of dilation: how you can literally experience more or less time based on how fast you're traveling compared to someone else. And even stranger than that? As we saw in the movie Interstellar, just spending time near a very massive object, like a black hole, can cause these same relativistic effects. Because mass and acceleration are sort of the same thing? Honestly, it's enough to give you a massive headache. But just because I find the concept baffling, I'm still going to keep chipping away, trying to understand more about it and help you wrap your brain around it too. For my own benefit, for your benefit, but mostly for my benefit. There's a great anecdote in the history of physics – it's probably not what actually happened, but I still love it. One of the most famous astronomers of the 20th century was Sir Arthur Eddington, played by a dashing David Tennant in the 2008 movie, Einstein and Eddington. Which, you should really see, if you haven't already. So anyway, Doctor Who, I mean Eddington, had worked out how stars generate energy (through fusion) and personally confirmed that Einstein's predictions of General Relativity were correct when he observed a total Solar Eclipse in 1919. Arthur Eddington Apparently during a lecture by Sir Arthur Eddington, someone asked, "Professor Eddington, you must be one of the three people in the world who understands General Relativity." He paused for a moment, and then said, "yes, but I'm trying to think of who the third person is." It's definitely not me, but I know someone who does have a handle on General Relativity, and that's Dr. Brian Koberlein, an astrophysics professor at the Rochester Institute of Technology. He covers this topic all the time on his blog, One Universe At A Time, which you should totally visit and read at briankoberlein.com. In fact, just to demonstrate how this works, Brian has conveniently pushed his RIT office to nearly light speed, and is hurtling towards us right now. Dr. Brian Koberlein: Hi Fraser, thanks for having me. If you can hang on one second, I just have to slow down. Fraser Cain: What just happened there? Why were you all slowed down? Brian: It's actually an interesting effect known as time dilation. One of the things about light is that no matter what frame of reference you're in, no matter how you're moving through the Universe, you'll always measure the speed of light in a vacuum to be the same. About 300,000 kilometres per second. And in order to do that, if you are moving relative to me, or if I'm moving relative to you, our references for time and space have to shift to keep the speed of light constant. As I move faster away from you, my time according to you has to appear to slow down. On the same hand, your time will appear to slow down relative to me. And that time dilation effect is necessary to keep the speed of light constant. Fraser: Does this only happen when you're moving? A representation of the coordinate system of the warped space around Earth. Credit: NASA Brian: Time dilation doesn't just occur because of relative motion, it can also occur because of gravity. Einstein's theory of relativity says that gravity is a property of the warping of space and time. So when you have a mass like Earth, it actually warps space and time. If you're standing on the Earth, your time appears to move a little bit more slowly than someone up in space, because of the difference in gravity. Now, for Earth, that doesn't really matter that much, but for something like a black hole, it could matter a great deal. As you get closer and closer to a black hole, your time will appear to slow down more and more and more. Fraser: What would this mean for space travel? Brian: In many times in science fiction, you'll see the idea of a rocket moving very close to the speed of light, and using time dilation to travel to distant stars. But you could actually do the same thing with gravity. If you had a black hole that was going out to another star or another galaxy, you could actually take your spaceship and orbit it very close to the black hole. And your time would seem to slow down. While you're orbiting the black hole, the black hole would take its time to get to another star or another galaxy, and for you it would seem really quick. Orbiting near a moving black hole doesn’t seem like the safest mode of transportation, but time dilation might make it worth the risk. Credit: NAOJ So that's another way that you could use time dilation to travel to the stars, at least in science fiction. Fraser: All right Brian, I've got one final question for you. If you get more massive as you get closer to the speed of light, could you get so much mass that you turn into a black hole? I'd like you to answer this question in the form of a blog post on briankoberlein.com and on the Google+ post we're going to link right here. Brian: Thanks Fraser, I'll have that answer up on my website. Once again, we visited the baffling realm of time dilation, and returned relatively unscathed. It doesn't mean that I understand it any better, but I hope you do, anyway. Once again, a big thanks to Dr. Koberlein for taking a few minutes out of his relativistic travel to answer our questions. Make sure you visit his blog and read his answer to my question. The post What is Time Dilation? appeared first on Universe Today.        • Email to a friend • View comments • Track comments •   New System Discovered with Five Planets NASA's planet-discovering Kepler mission suffered a major mechanical failure in May 2013, but thanks to innovative techniques subsequently implemented by astronomers the satellite continues to uncover worlds beyond our Solar System (i.e., exoplanets).  Indeed, Andrew Vanderburg (CfA) and colleagues just published results highlighting a new system found to host five transiting planets, which include: two sub-Neptune sized planets, a Neptune sized planet, a sub-Saturn sized planet, and a Jupiter sized planet. The team was able to identify the rare suite of five planets in Kepler's extended mission data by developing algorithms that attempt to compensate for the satellite's instability, which resulted from the mechanical failure that occurred in 2013.  A member on the team, Martti H. Kristiansen, identified the five transits in diagrams subsequently produced by their pipeline.  The image below conveys the raw and corrected data, whereupon bona fide transits are readily discernible in the latter. Vanderburg and colleagues obtained spectra that implies the star hosting the planets (designated HIP 41378) is relatively similar to the Sun, featuring a radius and mass of 1.4 and 1.15 times that of the Sun, respectively.  However, the planets in the newly discovered system were found to complete their orbits in a comparatively short time (typically less than 1 year).    The shorter orbital periods are often a result of a selection bias that stems from efforts aimed at detecting planetary systems using the transit method, which uncovers planets by identifying the drop in brightness that occurs as an exoplanet passes in front of its host star along our sight-line.  Such transits are rare because of the impracticality of monitoring a target host star unceasingly, and because of orientation effects (i.e., a near edge-on perspective is required).   The Kepler satellite monitored HIP 41378 for 75 days. The original Kepler mission observed a 110 square degree field for four years, and Vanderburg noted Kepler's extended (K2) mission could survey an area up to 20 times larger, thus significantly increasing the number of objects observed.  In particular, it is hoped that a suite of new exoplanets could be discovered orbiting brighter host stars, as those identified during the original Kepler mission were typically faint.  Precise velocity measurements are difficult to achieve for fainter stars, and the data are needed to complement brightness measurements and further characterize the exoplanets discovered.  Specifically, results inferred from the transit search method are often paired with those determined from velocity (Doppler) analyses to yield the density of the planetary systems (e.g., is it a water world?).   Vanderburg noted that the system they discovered possesses amongst the brightest planet host stars from either the Kepler or K2 missions, and is an ideal target for future velocity observations, "it could therefore be detectable with spectrographs like HARPS-N and HIRES in the northern hemisphere, and HARPS and PFS in the south." The Kepler satellite provides an advantageously large field of view, to enable the simultaneous monitoring of numerous targets, yet a disadvantage is that its resolution is rather coarse.  Indeed, the comparatively poor resolution can result in spurious transit signals ("planet impostors"), which are actually binary star systems in disguise.  "There are many things in the sky that can produce transit-like signals that are not planets, and thus we must be sure to identify what really is a planet detected by Kepler," Stephen Bryson told Universe Today in 2013.  A pseudo planetary transit could occur owing to a chance superposition of a bright star and a fainter eclipsing binary system, whereby the objects lie at different distances along the sight-line.  The bright foreground star dilutes the typically large eclipses produced by the binary system, hence mimicking the smaller eclipses displayed by transiting planets.   Vanderburg and colleagues evaluated that possibility by obtaining higher-resolution images using the Robo-AO adaptive optics system on the 2.1-m telescope at the Kitt Peak National Observatory.  The adaptive optics system helps correct distortions imposed by Earth's atmosphere, thus yielding an admirably high-resolution image that did not appear to feature contaminating stars. Vanderburg noted optimistically that, "Discoveries such as the HIP 41378 system show the value of wide-field space-based transit surveys. The Kepler spacecraft had to search almost 800 square degrees of sky (or seven fields of view) before finding such a bright multi-planet system suitable for follow-up observations. HIP 41378 is a preview of the type of discoveries the TESS satellite (2017 launch date) will make routine."   The Vanderburg et al. 2016 study has been accepted for publication in the Astrophysical Journal Letters, and a preprint is available on arXiv.  The coauthors on the study are Juliette C. Becker, Martti H. Kristiansen, Allyson Bieryla, Dmitry A. Duev, Rebecca Jensen-Clem, Timothy D. Morton, David W. Latham, Fred C. Adams, Christoph Baranec, Perry Berlind, Michael L. Calkins, Gilbert A. Esquerdo, Shrinivas Kulkarni, Nicholas M. Law, Reed Riddle, Maissa Salama, and Allan R. Schmitt.  If you'd like to help the Kepler team identify planets around other stars: join the Planet Hunters citizen science project. The post New System Discovered with Five Planets appeared first on Universe Today.        • Email to a friend • View comments • Track comments •   Curiosity Finds Ancient Mars Likely Had More Oxygen and Was More Hospitable to Life New chemical science findings from NASA's Mars rover Curiosity indicate that ancient Mars likely had a higher abundance of molecular oxygen in its atmosphere compared to the present day and was thus more hospitable to life forms, if they ever existed. Thus the Red Planet was much more Earth-like and potentially habitable billions of years ago compared to the cold, barren place we see today. Curiosity discovered high levels of manganese oxide minerals in rocks investigated at a location called "Windjana" during the spring of 2014. Manganese-oxide minerals require abundant water and strongly oxidizing conditions to form. "Researchers found high levels of manganese oxides by using a laser-firing instrument on the rover. This hint of more oxygen in Mars' early atmosphere adds to other Curiosity findings -- such as evidence about ancient lakes -- revealing how Earth-like our neighboring planet once was," NASA reported. The newly announced results stem from results obtained from the rovers mast mounted ChemCam or Chemistry and Camera laser firing instrument. ChemCam operates by firing laser pulses and then observes the spectrum of resulting flashes of plasma to assess targets' chemical makeup. "The only ways on Earth that we know how to make these manganese materials involve atmospheric oxygen or microbes," said Nina Lanza, a planetary scientist at Los Alamos National Laboratory in New Mexico, in a statement. "Now we're seeing manganese oxides on Mars, and we're wondering how the heck these could have formed?" The discovery is being published in a new paper in the American Geophysical Union's Geophysical Research Letters. Lanza is the lead author. The manganese oxides were found by ChemCam in mineral veins investigated at "Windjana" and are part of geologic timeline being assembled from Curiosity's research expedition across of the floor of the Gale Crater landing site. Scientists have been able to link the new finding of a higher oxygen level to a time when groundwater was present inside Gale Crater. "These high manganese materials can't form without lots of liquid water and strongly oxidizing conditions," says Lanza. "Here on Earth, we had lots of water but no widespread deposits of manganese oxides until after the oxygen levels in our atmosphere rose." The high-manganese materials were found in mineral-filled cracks in sandstones in the "Kimberley" region of the crater. High concentrations of manganese oxide minerals in Earth's ancient past correspond to a major shift in our atmosphere's composition from low to high oxygen atmospheric concentrations. Thus its reasonable to suggest the same thing happened on ancient Mars. As part of the investigation, Curiosity also conducted a drill campaign at Windjana, her 3rd of the mission. How much manganese oxide was detected and what is the meaning? "The Curiosity rover observed high-Mn abundances (>25 wt% MnO) in fracture-filling materials that crosscut sandstones in the Kimberley region of Gale crater, Mars," according to the AGU paper. "On Earth, environments that concentrate Mn and deposit Mn minerals require water and highly oxidizing conditions, hence these findings suggest that similar processes occurred on Mars." "Based on the strong association between Mn-oxide deposition and evolving atmospheric dioxygen levels on Earth, the presence of these Mn-phases on Mars suggests that there was more abundant molecular oxygen within the atmosphere and some groundwaters of ancient Mars than in the present day." Stay tuned here for Ken's continuing Earth and planetary science and human spaceflight news. Ken Kremer The post Curiosity Finds Ancient Mars Likely Had More Oxygen and Was More Hospitable to Life appeared first on Universe Today.        • Email to a friend • View comments • Track comments •         You Might Like Click here to safely unsubscribe from "Universe Today." Click here to view mailing archives, here to change your preferences, or here to subscribe • Privacy Email subscriptions powered by FeedBlitz, LLC, 365 Boston Post Rd, Suite 123, Sudbury, MA 01776, USA.