Artist's conception of Juno coming near Earth on a planned flyby Oct. 9, 2013. Credit: NASA
Every so often, engineers send a spacecraft in Earth’s general direction to pick up a speed boost before heading elsewhere. But sometimes, something strange happens — the spacecraft’s speed varies in an unexpected way. Even stranger, this variation happens only during some Earth flybys.
“We detected the flyby anomaly during Rosetta’s first Earth visit in March 2005,” stated Trevor Morley, a flight dynamics specialist at the European Space Agency’s European Space Operations Centre in Darmstadt, Germany.
“Frustratingly, no anomaly was seen during Rosetta’s subsequent Earth flybys in 2007 and 2011. This is a real cosmic mystery that no one has yet figured out.”
The phenomenon has been noticed in several spacecraft (both from ESA and NASA) since 1990. NASA’s NEAR asteroid spacecraft in January 1998 had the largest change, of 13 millimeters (0.5 inches) a second. The smallest variations, with NASA’s Saturn-bound Cassini in 1999 and Mercury-pointing MESSENGER in 2005, were below the threshold of measurement.
ESA won’t even speculate on what’s going on. “The experts are stumped,” the agency says in a press release.
Those experts, however, do have some ideas on how to track that down. ESOC plans to watch Juno’s flyby using a 35 meter deep-space dish in Malargüe, Argentina, as well as a 15-meter dish in Perth, Australia
“The stations will record highly precise radio-signal information that will indicate whether Juno speeds up or slows down more or less than predicted by current theories,” ESA states.
What do you think is going on? Let us know in the comments!
And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.
A 1909 penny being carried by the Mars Curiosity rover is caked with dust on Oct. 2, 2013, after 14 months on Mars. Credit: NASA/JPL-Caltech/MSSS/Planetary Science Institute
A high-power camera on the Mars Curiosity rover snapped a picture of a 1909 American penny featuring Abraham Lincoln. The coin is used as a calibration target for the Mars Hand Lens Imager (MAHLI) that is at the end of Curiosity’s robotic arm. In just over an Earth year on the Red Planet, you can see the bright copper is muted by lots of Mars dust.
Although the image has public relations appeal, there are scientific reasons behind picking that particular calibration target. It is supposed to measure how well the camera is performing, which is important as it zooms in on interesting features on Mars.
“The image shows that, during the penny’s 14 months (so far) on Mars, it has accumulated Martian dust and clumps of dust, despite its vertical mounting position,” the Planetary Science Institute stated.
Curiosity’s calibration target, shown before launch. Two instruments at the end of the robotic arm on NASA’s Mars rover Curiosity use the calibration targets attached to a shoulder joint of the arm. Credit: NASA/JPL-Caltech
“At 14 micrometers per pixel, this is the highest resolution image that the MAHLI can acquire,” the statement added.
“This image was obtained as part of a test; it was the first time that the rover’s robotic arm placed the MAHLI close enough to a target to obtain MAHLI’s highest-possible resolution. The previous highest-resolution MAHLI images, which were pictures of Martian rocks, were at 16-17 micrometers per pixel. A micrometer, also known as a micron, is about 0.000039 inches.”
Mauna Kea summit as seen from the northeast. Credit: University of Hawaii.
An astronomy student at Mauna Kea Observatories in Hawaii took some time off from his work to share the experience of being on the summit, gazing at the telescopes. The result is a nearly three-minute long time lapse video that makes you feel like you’re standing right next to those observatories.
Watching the telescopes move by day is mesmerizing enough, but stick around a few seconds and then you will see galaxies, stars and other cosmic sights pop into view — right behind the observatories that are looking at the same things.
“This montage was filmed on three nights in April (I was observing on one of the telescopes and would walk outside when things got boring) and four nights during summer 2013,” wrote Sean Goebel on the Vimeo page hosting the video. You can check out more of his timelapse photography at this website.
Trajectory Map of Juno’s Earth Flyby on Oct. 9, 2013. The Earth gravity assist is required to accelerate Juno’s arrival at Jupiter on July 4, 2016 and will captured unprecedented movie of Earth/Moon system. Credit: NASA/JPL
Trajectory Map of Juno’s Earth Flyby on Oct. 9, 2013
The Earth gravity assist is required to accelerate Juno’s arrival at Jupiter on July 4, 2016 and will capture an unprecedented movie of the Earth/Moon system. Credit: NASA/JPL
Details on how to watch via Slooh – see below [/caption]
NASA’s solar powered Jupiter-bound Juno orbiter is careening towards Earth for an absolutely critical gravity assisted fly by speed boost while capturing an unprecedented movie view of the Earth/Moon system – on its ultimate quest to unveiling Jupiter’s genesis!
“Juno will flyby Earth on October 9 to get a gravity boost and increase its speed in orbit around the Sun so that it can reach Jupiter on July 4, 2016,” Juno chief scientist Dr. Scott Bolton told Universe Today in an exclusive new Juno mission update – as the clock is ticking to zero hour. “The closest approach is over South Africa.”
All this ‘high frontier’ action comes amidst the utterly chaotic US government partial shutdown, that threatened the launch of the MAVEN Mars orbiter, has halted activity on many other NASA projects and stopped public announcements of the safe arrival of NASA’s LADEE lunar orbiter on Oct. 6, Juno’s flyby and virtually everything else related to NASA!
Bolton confirmed that the shutdown fortunately hasn’t altered or killed Juno’s flyby objectives. And ops teams at prime contractor Lockheed Martin have rehearsed and all set.
And some more good news is that Slooh will track the Juno Earth Flyby “LIVE” – for those hoping to follow along. Complete details below!
“The shutdown hasn’t affected our operations or plans, Bolton told me. Bolton is Juno’s principal investigator from the Southwest Research Institute (SwRI), San Antonio, Texas.
“Juno is 100% healthy.”
“But NASA is unable to participate in our public affairs and press activities,” Bolton elaborated.
NASA’s Juno Jupiter-bound space probe will fly by Earth for essential speed boost on Oct 9, 2013. Credit: NASA/JPL
97% of NASA’s employees are furloughed – including public affairs – due to the legal requirements of the shutdown!
Credit: NASA/JPLJuno will also capture an unprecedented new movie of the Earth/Moon system.
A full up science investigation of our Home Planet by Juno is planned, that will also serve as a key test of the spacecraft and its bevy of state of the art instruments.
“During the earth flyby we have most of our instruments on and will obtain a unique movie of the Earth Moon system on our approach.
“We will also calibrate instuments and measure earth’s magnetosphere, obtain closeup images of the Earth and the Moon in UV [ultraviolet] and IR [infrared],” Bolton explained to Universe Today.
The flyby will accelerate the spacecraft’s velocity by 16,330 mph.
Where is the best view of Juno’s flyby, I asked?
“The closest approach is over South Africa and is about 500 kilometers [350 miles],” Bolton replied.
The time of closest approach is 3:21 p.m. EDT (12:21 PDT / 19:21 UTC) on Oct. 9, 2013
Watch this mission produced video about Juno and the Earth flyby:
Video caption: On Oct. 9, 2013, NASA’s Jupiter-bound Juno spacecraft is making a quick pass to get a gravity boost from the mother planet. Dr. Scott Bolton of Southwest Research Institute® is the Juno mission principal investigator, leading an international science team seeking to answer some fundamental questions about the gas giant and, in turn, about the processes that led to formation of our solar system.
NASA’s Juno spacecraft blasted off atop an Atlas V rocket two years ago from Cape Canaveral Air Force Station, FL, on Aug. 5, 2011 to begin a 2.8 billion kilometer science trek to discover the genesis of Jupiter hidden deep inside the planet’s interior.
Juno is on a 5 year and 1.7 Billion mile (2.8 Billion km) trek to the largest planet in our solar system. When it arrives at Jupiter on July 4, 2016, Juno will become the first polar orbiting spacecraft at the gas giant.
During a one year science mission – entailing 33 orbits lasting 11 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 genesis and evolution.
The goal is to find out more about the planets origins, interior structure and atmosphere, observe the aurora, map the intense magnetic field and investigate the existence of a solid planetary core
Why does Juno need a speed boost from Earth?
“A direct mission to Jupiter would have required about 50 percent more fuel than we loaded,” said Tim Gasparrini, Juno program manager for Lockheed Martin Space Systems, in a statement.
“Had we not chosen to do the flyby, the mission would have required a bigger launch vehicle, a larger spacecraft and would have been more expensive.”
Juno soars skyward to Jupiter on Aug. 5, 2011 from launch pad 41 at Cape Canaveral Air Force Station at 12:25 p.m. EDT. View from the VAB roof. Credit: Ken Kremer/kenkremer.com
Viewers near Cape Town, South Africa will have the best opportunity to view the spacecraft traveling across the sky.
Juno itself will most likely not be visible to the unaided eye, but binoculars or a small telescope with a wide field should provide an opportunity to view, according to a Slooh statement.
Slooh will track Juno live on October 9th, 2013.
Check here for international starting times: http://goo.gl/7ducFs – and for the Slooh broadcast hosted by Paul Cox.
Viewers can view the event live on Slooh.com using their computer or mobile device, or by downloading the free Slooh iPad app in the iTunes store. Questions can be asked during the broadcast via Twitter by using the hashtag #nasajuno -says Slooh.
Amidst the government shutdown, Juno prime contractor Lockheed Martin is working diligently to ensure the mission success.
Because there are NO 2nd chances!
“The team is 100 percent focused on executing the Earth flyby successfully,” said Gasparrini.
“We’ve spent a lot of time looking at possible off-nominal conditions. In the presence of a fault, the spacecraft will stay healthy and will perform as planned.”
Stay tuned here for continuing Juno, LADEE, MAVEN and more up-to-date NASA news.
And be sure to check back here for my post-flyby update.
What’s not at all clear is whether Juno will detect any signs of ‘intelligent life’ in Washington D.C.!
Learn more about Juno, LADEE, MAVEN, Curiosity, Mars rovers, Cygnus, Antares, SpaceX, Orion, the Gov’t shutdown and more at Ken’s upcoming presentations
Oct 8: “NASA’s Historic LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”& “Curiosity, MAVEN, Juno and Orion updates”; Princeton University, Amateur Astronomers Assoc of Princeton (AAAP), Princeton, NJ, 8 PM
Neptune's system of moons and rings visualized. Credit: SETI
“That’s no moon…”
-B. Kenobi
But in this case, it is… a lost moon of Neptune not seen since its discovery in the late 1980’s.
A new announcement from the 45th Meeting of the Division for Planetary Sciences of the American Astronomical Society being held this week in Denver, Colorado revealed the recovery of a moon of Neptune that was only briefly glimpsed during the 1989 flyby of Voyager 2.
The re-discovery Naiad, the innermost moon of Neptune, was done by applying new processing techniques to archival Hubble images and was announced today by Mark Showalter of the SETI institute.
Collaborators on the project included Robert French, also from the SETI Institute, Dr. Imke de Pater of UC Berkeley, and Dr. Jack Lissauer of the NASA Ames Research Center.
The findings were a tour-de-force of new techniques applied to old imagery, and combined the ground-based 10 meter Keck telescope in Hawaii as well as Hubble imagery stretching back to December 2004.
The chief difficulty in recovering the diminutive moon was its relative faintness and proximity to the “dazzling” disk of Neptune. At roughly 100 kilometres in diameter and an apparent magnitude of +23.9, Naiad is over a million times fainter than +8th magnitude Neptune. It’s also the innermost of Neptune’s 14 known moons, and orbits once every 7 hours just 23,500 kilometres above the planet’s cloud tops. Neptune itself is about 49,000 kilometres in diameter, and only appears 2.3” in size from Earth. From our Earthly vantage point, Naiad only strays about arc second from the disk of Neptune, a tiny separation.
“Naiad has been an elusive target ever since Voyager left the Neptune system,” Showalter said in a recent SETI Institute press release. Voyager 2 has, to date, been the only mission to explore Uranus and Neptune.
To catch sight of the elusive inner moon, Showalter and team applied new analyzing techniques which filtered for glare and image artifacts that tend to “spill over” from behind the artificially occulted disk of Neptune.
Other moons, such as Galatea and Thalassa — which were also discovered during the 1989 Voyager 2 flyby — are also seen in the new images. In fact, the technique was also used to uncover the as of yet unnamed moon of Neptune, S/2004 N1 which was revealed earlier this year.
Naiad is named after the band of nymphs in Greek mythology who inhabited freshwater streams and ponds. The Naiads differed from the saltwater-loving Nereids of mythology fame, after which another moon of Neptune discovered by Gerard Kuiper in 1949 was named.
It’s also intriguing to note that Naiad was discovered in a significantly different position in its orbit than expected. Clearly, its motion is complex due to its interactions with Neptune’s other moons.
“We don’t quite have enough observations to establish a refined orbit,” Mr. Showalter told Universe Today, noting that there may still be some tantalizing clues waiting to be uncovered from the data.
I know the burning question you have, and we had as well during the initial announcement today. Is it REALLY Naiad, or another unknown moon? Showalter notes that this possibility is unlikely, as both objects seen in the Hubble and Voyager data are the same brightness and moving in the same orbit. To invoke Occam’s razor, the simplest solution— that both sightings are one in the same object —is the most likely.
“Naiad is well inside Neptune’s Roche Limit, like many moons in the solar system,” Mr. Showalter also told Universe Today. Naiad is also well below synchronous orbit, and is likely subject to tidal deceleration and may one day become a shiny new ring about the planet.
The labeled ring arcs of Neptune as seen in newly processed data. The image spans 26 exposures combined into an equivalent 95 minute exposure. The ring trace and an image of the occulted planet Neptune is added for reference. (Credit: M. Showalter/SETI Institute).
And speaking of which, the tenuous rings of Neptune have also evolved noticeably since the 1989 Voyager flyby. First discovered from the ESO La Silla Observatory in 1984, data using the new techniques show that the knotted ring segments named the Adams and Le Verrier have been fading noticeably.
“In a decade or two, we may see an ‘arc-less’ ring,” Showalter noted during today’s Division for Planetary Sciences press conference. The two ring segments observed are named after Urbain Le Verrier and John Couch Adams, who both calculated the position of Neptune due to orbital perturbations of the position of Uranus. Le Verrier beat Adams to the punch, and Neptune was first sighted from the Berlin Observatory on the night of September 23rd, 1846. Observers of the day were lucky that both planets had undergone a close passage just decades prior, or Neptune may have gone unnoticed for considerably longer.
The rings of Neptune as seen from Voyager 2 during the 1989 flyby. (Credit: NASA/JPL).
Neptune has completed just over one 164.8 year orbit since its discovery. It also just passed opposition this summer, and is currently a fine telescopic object in the constellation Aquarius.
Unfortunately, there aren’t any plans for a dedicated Neptune mission in the future. New Horizons will cross the orbit of Neptune in August 2014, though it’s headed in the direction of Pluto, which is currently in northern Sagittarius. New Horizons was launched in early 2006, which gives you some idea of just how long a “Neptune Orbiter” would take to reach the outermost ice giant, given today’s technology.
This represents the first time that Naiad has been imaged from the vicinity of Earth, and demonstrates a new processing technique capable of revealing new objects in old Hubble data.
“We keep discovering new ways to push the limit of what information can be gleaned from Hubble’s vast collection of planetary images,” Showalter said in the SETI press release.
Congrats to Showalter and team on the exciting recovery… what other moons, both old and new, lurk in the archives waiting to be uncovered?
– Read today’s SETI Institute press release on the recovery of Naiad.
-Be sure to follow all the action at the 45th DPS conference in Denver this week!
Jupiter with polka dot shadows cast by Io, Europa and Callisto as depicted around 1 a.m. EDT Oct. 12. Watch for the Great Red Spot to come into view during the transit. Created with Claude Duplessis' Meridian software
Talk about a great fall lineup. Three of Jupiter’s four brightest moons plan a rare show for telescopic observers on Friday night – Saturday morning Oct. 11-12. For a span of just over an hour, Io, Europa and Callisto will simultaneously cast shadows on the planet’s cloud tops, an event that hasn’t happened since March 28, 2004.
Who doesn’t remember their first time looking at Jupiter and his entourage of dancing moons in a telescope? Because each moves at a different rate depending on its distance from the planet, they’re constantly on the move like kids in a game of musical chairs. Every night offers a different arrangement.
Jupiter and its four brightest moons seen in a small telescope. Credit: Bob King
Some nights all four of the brightest are strung out on one side of the planet, other nights only two or three are visible, the others hidden behind Jupiter’s “plus-sized” globe. Occasionally you’ll be lucky enough to catch the shadow of one of moons as it transits or crosses in front of the planet. We call the event a shadow transit, but to someone watching from Jupiter, the moon glides in front of the sun to create a total solar eclipse.
Since the sun is only 1/5 as large from Jupiter as seen from Earth, all four moons are large enough to completely cover the sun and cast inky shadows. To the eye they look like tiny black dots of varying sizes. Europa, the smallest, mimics a pinprick. The shadows of Io and Callisto are more substantial. Ganymede, the solar system’s largest moon at 3,269 miles (5,262 km), looks positively plump compared to the others. Even a small telescope magnifying around 50x will show it.
Jupiter on Sept. 24 with its moon Europa (at left) casting a pinhead black shadow on Jupiter’s clouds. Credit: John Chumack
The three inner satellites – Io, Europa and Ganymede – have shadow transits every orbit. Distant Callisto only transits when Jupiter’s tilt relative to Earth is very small, i.e. the plane of the planet’s moons is nearly edge-on from our perspective. Callisto transits occur in alternating “seasons” lasting about 3 years apiece. Three years of shadow play are followed by three years of shadowless misses. Single transits are fairly common; you can find tables of them online like this one from Project Pluto or plug in time and date into a free program like Meridian for a picture and list of times.
Because Io, Europa and Ganymede orbit in a 4:2:1 resonance (Io revolves four times around Jupiter in the time it takes Ganymede to orbit once; Europa completes two orbits for Ganymede’s one) it’s impossible for all three to line up – along with Callsto – for a “quadruple transit”. Credit: Matma Rex / Wikipedia
Seeing two shadows inch across Jupiter’s face is very uncommon, and three are as rare as a good hair day for Donald Trump. Averaged out, triple transits occur once or twice a decade. Friday night Oct. 11 each moon enters like actors in a play. Callisto appears first at 11:12 p.m. EDT followed by Europa and then Io. By 12:32 a.m. all three are in place.
Catch them while you can. Groups like these don’t last long. A little more than an hour later Callisto departs, leaving just two shadows. You’ll find the details below. All times are Eastern Daylight or EDT. Subtract one hour for Central time and add four hours for BST (British Summer Time):
* Callisto’s shadow enters the disk – 11:12 p.m. Oct. 11
* Europa – 11:24 p.m.
* Io – 12:32 a.m. ** TRIPLE TRANSIT from 12:32 – 1:37 a.m.
* Callisto departs – 1:37 a.m.
* Europa departs – 2:01 a.m.
* Io departs – 2:44 a.m.
Looking at Jupiter from high above the plane of the solar system in this diagram from more than a century ago, we can better picture how shadow transits and eclipses happen. The tiny disk of Io and the shadow of Ganymede are seen in transit; Callisto is about to be eclipsed by Jupiter’s shadow. Credit: Garrett Serviss from “Pleasures of the Telescope” (annotations: Bob King)
The triple transit will be seen across the eastern half of the U.S., Europe and western Africa. Those living on the East Coast have the best view in the U.S. with Jupiter some 20-25 degrees high in the northeastern sky around 1 a.m. local time. Things get dicier in the Midwest where Jupiter climbs to only 5-10 degrees. From the mountain states the planet won’t rise until Callisto’s shadow has left the disk, leaving a two-shadow consolation prize. If you live in the Pacific time zone and points farther west, you’ll unfortunately miss the event altogether.
From the Eastern Time Zone Jupiter will be well-placed in the eastern sky during the transit. Created with Stellarium
Key to seeing all three shadows clearly, especially if Jupiter is low in the sky, is steady air or what skywatchers call “good seeing”. The sky can be so clear you’d swear there’s a million stars up there, but a look through the telescope will sometimes show dancing, blurry images due to invisible air turbulence. That’s “bad seeing”. Unfortunately, bad seeing is more common near the horizon where we peer through a greater thickness of atmosphere. But don’t let that keep you inside Friday night. With a spell of steady air, all you need is a 4-inch or larger telescope magnifying around 100x to spot all three.
The March 28, 2004 triple transit. Shadows from left: Ganymede, Io and Callisto. You can also see the disks of Io (white dot) and Ganymede (blue dot) in this photo taken in infrared light by the Hubble Space Telescope. Credit: NASA/ESA
If bad weather blocks the view, there are two more triple transits coming up soon – a 95-minute-long event on June 3, 2014 starring Europa, Ganymede and Callisto (not visible in the Americas) and a 25-minute show on Jan. 24, 2015 featuring Io, Europa and Callisto and visible across Western Europe and the Americas. That’s it until dual triple transits in 2032.
Over the past few years, the field of astrobiology has made great strides. With missions such as Kepler making exoplanet discoveries commonplace, the question no longer is “Are other planets out there?” but “When will we find a true twin of Earth?”
A new book, “Five Billion Years of Solitude,” takes the reader from the earliest efforts of astrobiology, along with information on how life took hold on Earth, to how we can use that information to help understand how life may flourish on other worlds – all while giving us a glimpse inside the minds of some of the field’s most notable scientists.
To say that author Lee Billings tackles only the subject of astrobiology in “Five Years of Solitude” would be selling this book extremely short. While the main focus of the book is life on Earth and the possibility of life elsewhere, readers will find “Five Years of Solitude” incredibly engaging. Combining conversations with such legends like Frank Drake and Sara Seager with in-depth discussions of numerous science topics related to the search for life, Billings has created a book that is not only entertaining, but educational as well.
For those who aren’t well-versed in the details of astrobiology, the casual, “conversational” approach Billings takes to presenting scientific concepts makes for easily digestible reading. While the scientific concepts explained in the book are laid out in good detail, Billings doesn’t present them in an overly dry, or boring manner. Weaving scientific knowledge with interviews from heavy hitters in the world of astrobiology is one of the book’s strongest selling points. The book is both a primer on astrobiology, and a collection of knowlegde from some of the greatest minds in the field.
In the many conversations Billings has with people such as Geoff Marcy, Frank Drake, Sara Seager, and many others, one can get a “feel” for the sometimes insurmountable obstacles scientists face in trying to get their projects approved and funded. Readers will finish “Five Billion Years of Solitude” with a deep appreciation for the miracle of life on Earth, and the hard work and dedication researchers invest in understanding life on Earth, and the possibility of life elsewhere.
Additionally, Billings provides a gold mine of additional materials that readers can dive into if they want to immerse themselves much deeper into the field of astrobiology. If you are interested in the field of Astrobiology, and understanding how life developed on Earth (and possibly elsewhere), you’ll find “Five Billion Years of Solitude” a very engaging book.
Ask anyone, “what color is the Sun”? and they’ll tell you the obvious answer: it’s yellow.
But is it really?
Please don’t go check, it’s not safe to look directly at the Sun with your unprotected eyes.
From our perspective it does look a little yellow, especially after sunrise or shortly before sunset,
But don’t be fooled.
If you could travel into space and look at the Sun without going blind, you’d find that it’s actually white, and not yellow.
Using a prism, you can see how sunlight can be broken up into the spectrum of its colors: red, orange, yellow, green, blue, indigo and violet. When you mix all those colors together, you get white.
Here’s the strange part.
If look at all the photons coming in, our star is actually sending the most photons in the green portion of the spectrum,
Our Sun appears yellow to us because of the atmosphere.
Photons in the higher end of the spectrum – blue, indigo and violet – are more likely to be scattered away, while the lower end of the spectrum – red, orange and yellow – are less easily scattered.
Credit: Niki GaidaWhen the Sun is close to the horizon, you’re seeing it distorted by more of the Earth’s atmosphere, scattering away the bluer photons and making it appear red.
When there’s smoke and pollution in the air, it enhances the effect and it will look even redder.
If the Sun is high in the sky, where it has the least amount of atmospheric interference, it will appear more blue.
The Sun. Credit and copyright: César Cantú.We’re so familiar with the Sun being yellowish-orange, that astronomers will artificially change the color of their images to look more yellowy.
But really, the Sun looks like a pure white ball – especially when you’re out in space.
Interestingly, the color of the Sun is very important to astronomers. They use a technique called spectroscopy to stretch out the spectrum of light coming from a star. Dark lines in this spectrum tell you exactly what it’s made of.
You can see which stars have high amounts of metals, or which are mostly hydrogen and helium, leftover from the Big Bang.
This color also tells you the temperature of the star. Cooler stars are actually redder. Betelgeuse is only 3500 Kelvin. Hotter stars, like Rigel, can get above 10000 Kelvin, and they look blue.
Our own Sun has a temperature of almost 5800 Kelvin, and when viewed outside of our atmosphere, appears white. in colour.
Illustration of 55 Cancri e, a super-Earth that’s thought to have a thick layer of diamond Credit: Yale News/Haven Giguere
A precious planet? Don’t think so fast, a new study says. The so-called “diamond super-Earth“, 55 Cancri e, may actually have a different composition than initially expected.
The team examined previous observations of the system, which is 40 light years from Earth, and said that there is less carbon (or what diamonds are made of) than oxygen in the planet’s star.
“In theory, 55 Cancri e could still have a high carbon to oxygen ratio and be a diamond planet, but the host star does not have such a high ratio,” stated University of Arizona astronomy graduate student Johanna Teske, who led the study.
“So in terms of the two building blocks of information used for the initial ‘diamond-planet’ proposal – the measurements of the exoplanet and the measurements of the star – the measurements of the star no longer verify that.”
Image Credit: www.daviddarling.info
The difficulty is it’s not so easy to send a spacecraft to a planet that is so far away from us, so we can’t do any close-up observations of it. This means that astronomers rely on methods such as absorption spectra (looking at what chemical elements absorb light at different wavelengths) of a star to see what it is made of.
The astronomers said there had been only a single oxygen line found in the last study, and they feel that 55 Cancri is cooler than the sun and has more metals into it. This conclusion would imply that the amount of oxygen in the star “is more prone to error.”
There are, however, a lot of moving pieces to this study. How do you know if a planet and star have similar compositions? How to accurately model a planet that you can’t see very well with conventional telescopes? How to best measure chemical abundances from afar? Teske acknowledged in a statement that her work may not be the definitive answer on this planet, so it will be interesting to see what comes out next.
The study has been accepted into the Astrophysical Journal. In the meantime, you can read the preprint version on Arxiv.
