Finding water on Mars is a primary focus of human efforts to understand the Red Planet. The presence of liquid water on Mars supports the theory that life existed there. Now it looks as though some puzzling features on the surface of Mars could have be…
Finding water on Mars is a primary focus of human efforts to understand the Red Planet. The presence of liquid water on Mars supports the theory that life existed there. Now it looks as though some puzzling features on the surface of Mars could have be…
Earth may have a new neighbour, in the form of an Earth-like planet in a solar system only 16 light years away. The planet orbits a star named Gliese 832, and that solar system already hosts two other known exoplanets: Gliese 832B and Gliese 832C. The …
Finding a ninth planet in our Solar System this late in the game would be fascinating. It would also be somewhat of a surprise, considering our observational capabilities. But new evidence, in the form of small perturbations in the orbit of the Cassini probe, points to the existence of an as-yet undetected planet in our solar system.
Back in January, Konstantin Batygin and Mike Brown, two planetary scientists from the California Institute of Technology, presented evidence supporting the existence of a ninth planet. Their paper showed that some Kuiper Belt Objects (KBOs) display unexpected behaviour. It appears that 6 KBOs are affected by their relationship to a large object, but the KBOs in question are too distant from the known gas giants for them to be responsible. They think that a large, distant planet, in the distant reaches of our Solar System, could be responsible for the unexpected orbital clustering of these KBOs.
Now, the Ninth Planet idea is gaining steam, and another team of researchers have presented evidence that small perturbations in the orbit of the Cassini spacecraft are caused by the new planet. Agnès Fienga at the Côte d’Azur Observatory in France, and her colleagues, have been working on a detailed model of the Solar System for over a decade. They plugged the hypothetical orbit and size of Planet Nine into their model, to see if it fit.
Planet Nine is calculated to be about 4 times as large as Earth, and 10 times as massive. It’s orbit takes between 10,000 and 20,000 years. A planet that large can only be hiding in so many places, and those places are a long way from Earth. Fienga found a potential home for Planet Nine, some 600 astronomical units (AU) from here. That much mass at that location could account for the perturbations in Cassini’s orbit.
There’s more good news when it comes to Planet Nine. By happy accident, it’s predicted location in the sky is towards the constellation Cetus, in the southern hemisphere. This means that it is in the view of the Dark Energy Survey, a southern hemisphere project that is studying the acceleration of the universe. The Dark Energy Survey is not designed to search for planetary objects, but it has successfully found at least one icy object.
There are other ways that the existence of Planet Nine could be confirmed. If it’s as large as thought, then it will radiate enough internal heat to be detected by instruments designed to study the Cosmic Microwave Background (CMB). There is also an enormous amount of data from multiple experiments and observations done over the years that might contain an inadvertent clue. But looking through it is an enormous task.
As for Brown and Batygin, who initially proposed the existence of Planet Nine based on the behaviour of KBOs, they are already proposing a more specific hunt for the elusive planet. They have asked for a substantial amount of observing time at the Subaru Telescope on Mauna Kea in Hawaii, in order to examine closely the location that Fienga’s solar system model predicts Planet Nine to be at.
For a more detailed look at Batygin’s and Brown’s work analyzing KBOs, read Matt Williams’ article here.
The post Mysterious Pull On Cassini Probe May Help Find Planet Nine appeared first on Universe Today.
On January 20th, 2016, researchers Konstantin Batygin and Michael E. Brown of Caltech announced that they had found evidence that hinted at the existence of a massive planet at the edge of the Solar System. Based on mathematical modeling and computer simulations, they predicted that this planet would be a super-Earth, two to four times Earth’s size and 10 times as massive. They also estimated that, given its distance and highly elliptical orbit, it would take 10,000 – 20,000 years to orbit the Sun.
Since that time, many researchers have responded with their own studies about the possible existence of this mysterious “Planet 9”. One of the latest comes from the University of Arizona, where a research team from the Lunar and Planetary Laboratory have indicated that the extreme eccentricity of distant Kuiper Belt Objects (KBOs) might indicate that they crossed paths with a massive planet in the past.
For some time now, it has been understood that there are a few known KBOs who’s dynamics are different than those of other belt objects. Whereas most are significantly controlled by the gravity of the gas giants planets in their current orbits (particularly Neptune), certain members of the scattered disk population of the Kuiper Belt have unusually closely-spaced orbits.
When Batygin and Brown first announced their findings back in January, they indicated that these objects instead appeared to be highly clustered with respect to their perihelion positions and orbital planes. What’s more, their calculation showed that the odds of this being a chance occurrence were extremely low (they calculated a probability of 0.007%).
Instead, they theorized that it was a distant eccentric planet that was responsible for maintaining the orbits of these KBOs. In order to do this, the planet in question would have to be over ten times as massive as Earth, and have an orbit that lay roughly on the same plane (but with a perihelion oriented 180° away from those of the KBOs).
Such a planet not only offered an explanation for the presence of high-perihelion Sedna-like objects – i.e. planetoids that have extremely eccentric orbits around the Sun. It would also help to explain where distant and highly inclined objects in the outer Solar System come from, since their origins have been unclear up until this point.
In a paper titled “Coralling a distant planet with extreme resonant Kuiper belt objects“, the University of Arizona research team – led by Renu Malhotra, the Louise Foucar Marshall Science Research Professor – looked at things from another angle. If in fact Planet 9 were crossing paths with certain high-eccentricity KBOs, they reasoned, it was a good bet that its orbit was in resonance with these objects.
To break it down, small bodies are ejected from the Solar System all the time due to encounters with larger objects that perturb their orbits. In order to avoid being ejected, smaller bodies need to be protected by orbital resonances. While the smaller and larger objects may pass within each others’ orbital path, they are never close enough that they would able to exert a significant influence on each other.
This is how Pluto has remained a part of the Solar System, despite having an eccentric orbit that periodically cross Neptune’s path. Though Neptune and Pluto cross each others orbit, they are never close enough to each other that Neptune’s influence would force Pluto out of our Solar System. Using this same reasoning, they hypothesized that the KBOs examined by Batygin and Brown might be in an orbital resonance with the Planet 9.
As Dr. Malhotra told Universe Today via email:
“The extreme Kuiper belt objects we investigate in our paper are distinct from the others because they all have very distant, very elliptical orbits, but their closest approach to the Sun isn’t really close enough for them to meaningfully interact with Neptune. So we have these six observed objects whose orbits are currently fairly unaffected by the known planets in our Solar System. But if there’s another, as yet unobserved planet located a few hundred AU from the Sun, these six objects would be affected by that planet.”
After examining the orbital periods of these six KBOs – Sedna, 2010 GB174, 2004 VN112, 2012 VP113, and 2013 GP136 – they concluded that a hypothetical planet with an orbital period of about 17,117 years (or a semimajor axis of about 665 AU), would have the necessary period ratios with these four objects. This would fall within the parameters estimated by Batygin and Brown for the planet’s orbital period (10,000 – 20,000 years).
Their analysis also offered suggestions as to what kind of resonance the planet has with the KBOs in question. Whereas Sedna’s orbital period would have a 3:2 resonance with the planet, 2010 GB174 would be in a 5:2 resonance, 2994 VN112 in a 3:1, 2004 VP113 in 4:1, and 2013 GP136 in 9:1. These sort of resonances are simply not likely without the presence of a larger planet.
“For a resonance to be dynamically meaningful in the outer Solar System, you need one of the objects to have enough mass to have a reasonably strong gravitational effect on the other,” said Malhotra. “The extreme Kuiper belt objects aren’t really massive enough to be in resonances with each other, but the fact that their orbital periods fall along simple ratios might mean that they each are in resonance with a massive, unseen object.”
But what is perhaps most exciting is that their findings could help to narrow the range of Planet 9’s possible location. Since each orbital resonance provides a geometric relationship between the bodies involved, the resonant configurations of these KBOs can help point astronomers to the right spot in our Solar System to find it.
But of course, Malhotra freely admits that several unknowns remain, and further observation and study is necessary before Planet 9 can be confirmed:
“There are a lot of uncertainties here. The orbits of these extreme Kuiper belt objects are not very well known because they move very slowly on the sky and we’ve only observed very small portions of their orbital motion. So their orbital periods might differ from the current estimates, which could make some of them not resonant with the hypothetical planet. It could also just be chance that the orbital periods of the objects are related; we haven’t observed very many of these types of objects, so we have a limited set of data to work with.”
Ultimately, astronomers and the rest of us will simply have to wait on further observations and calculations. But in the meantime, I think we can all agree that the possibility of a 9th Planet is certainly an intriguing one! For those who grew up thinking that the Solar System had nine planets, these past few years (where Pluto was demoted and that number fell to eight) have been hard to swallow.
But with the possible confirmation of this Super-Earth at the outer edge of the Solar System, that number could be pushed back up to nine soon enough!
Further Reading: arXiv.org
Science—like literature and the arts—helps nations cooperate together, even when they’re in conflict politically. The USA and Russia are in conflict over the Ukraine and Syria, yet both nations still cooperate when it comes to the International Space Station. With that in mind, it’s great to see other nations—in this case India—taking on a greater role in space exploration and sharing their scientific results.
India’s Mars Orbiter Mission (MOM) probe has been in orbit around Mars since September 2014, after being launched in November 2013. Though the Indian Space Research Organization (ISRO) has released plenty of pictures of the surface of Mars, they haven’t released any scientific data. Until now.
In September 2015, MOM’s orbit was adjusted to bring it to within 260 km of Mars’ surface, significantly closer to the surface than the usual 400 km altitude. This manoeuver allowed one of MOM’s six instruments, the Mars Exospheric Neutral Composition Analyzer (MENCA), to measure the atmospheric composition at different altitudes. The sensor measured carbon dioxide, oxygen, nitrogen and carbon monoxide to see how they were distributed at different altitudes.
MOM’s activity at Mars is important for a couple of reasons. Its results confirm the results of other probes that have studied Mars’ atmosphere. And confirmation is an important part of science. But there’s another reason why MOM is important, and this centres around the search for evidence of life on the Red Planet.
Methane is considered a marker for the presence of life. It’s not an absolute indicator that life is or was present, but it’s a good hint. One of MOM’s sensors is the Methane Sensor for Mars (MSM.) Methane has been detected in Mars’ atmosphere before, but these could have been spikes, and not a strong indicator of living processes. If MSM provides stronger data indicating a consistent methane presence, that would be very interesting.
Releasing these results is also vindication for ISRO. In 2008, ISRO released data from their lunar mission, Chandrayaan-1, showing the presence of water on the Moon. Those results, which were gathered with an instrument called Chandra’s Altitudinal Composition Explorer (CHACE) were rejected by several scientific publications, on the grounds that the results were contaminated. Only when they were confirmed by another of Chandrayaan-1’s instruments—the Moon Mineralogy Mapper (M3)—were the results accepted.
But MOM’s MENCA instrument is based on the CHACE instrument aboard Chandrayaan-1, so ISRO feels that MENCA’s success in the atmosphere at Mars vindicates CHACE’s results on the Moon. And rightly so.
You can read a blog post by Syed Maqbool Ahmed at the Planetary Society, where he talks about the success of MOM’s MENCA, and how it vindicates ISRO’s earlier results with CHACE that showed the presence of water on the Moon.
MOM is India’s first interplanetary mission, and is expected to last until its fuel runs out, which could take many years. India is the first Asian nation to make it to another planet, and the first of any nation to make it to Mars on their first attempt. Not bad for a mission that was initially considered to be only a technology demonstration mission.
The post appeared first on Universe Today.
Last month, planetary scientists Mike Brown and Konstantin Batygin of the California Institute of Technology found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer Solar System. Nicknamed Planet Nine, it’s estimated to be 10 times more massive than Earth with a diameter as large as 16,000 miles (25,750 km). The putative planet orbits about 20 times farther from the Sun on average than Neptune or some 56 billion miles away; at that tremendous distance it would take between 10,000 and 20,000 years to complete one orbit around the Sun.
Planet Nine’s existence is inferred through mathematical modeling and computer simulations based on the clustering of six remote asteroids in the Kuiper Belt, a vast repository of icy asteroids and comets beyond Neptune. Brown and Batyginsay there’s only a 0.007% chance or about 1 in 15,000 that the clustering could be a coincidence.
All well and good. But with such an enormous orbit, astronomers face the daunting task of searching vast swaths of space for this needle in a haystack. Where to begin? A study done by a team of French scientists may help narrow the search. In a recent paper appearing in Astronomy and Astrophysics, astronomer Agnes Fienga and colleagues looked at what effect a large Kuiper Belt planet would have on the orbits of other planets in the Solar System, focusing their study on Saturn. Thanks to NASA’s Cassini orbiter, which has been orbiting Saturn since 2004, we can precisely calculate Saturn’s position along its orbit.
Based on the planet’s “residuals”, the difference between the calculated position of Saturn versus what was actually observed, the team was able to exclude two sections of its potential orbit and home in on “probable” swath and a much larger “possible” section of the orbit. The process may sound familiar, since it was the one used to discover another planet more than 150 years ago — Neptune. Back then, irregularities (residuals) in the motion of Uranus led astronomers in 1847 to predict a more distant 8th planet as the cause. On September 24, 1846, Johann Galle discovered Neptune only 1° from its position predicted by French mathematician Urbain LeVerrier.
While the current solution for Planet Nine doesn’t come anywhere near as close, it’s a step in the right direction.
55 Cancri-e was once touted as one of the most exotic exo-planets ever discovered. Mass and radius modelling led some astronomers to speculate that its interior could be rich in carbon. And that much carbon crushed together under extreme pressure = diamonds. That’s how it got its nickname “Diamond Planet.”
But 55 Cancri-e—now named “Janssen” (Thank you International Astronomical Union!)—is even more exotic with the recent discovery of an atmosphere. A February 7th research paper in the Astrophysical Journal, by a team of European astronomers, reports that Janssen has an atmosphere rich in hydrogen. This makes Janssen the first exo-planet, that we know of, to have an atmosphere.
The team used the Wide Field Camera 3 (WDF3) on the Hubble Space Telescope, and a new scanning technique, to gain an understanding of Janssen’s atmosphere. Along with hydrogen, the team also found helium, and potentially, hydrogen cyanide.
Given Janssen’s surface temperature of 2000 K (1727 C), and its proximity to its host star, the existence of an atmosphere is surprising. The team suspects that the hydrogen-rich atmosphere is left over from the planet’s formation 8 billion years ago, and is a remnant of the nebula that the planet and star formed from.
“Our observations of 55 Cancri e’s atmosphere suggest that the planet has managed to cling on to a significant amount of hydrogen and helium from the nebula from which it formed,” said Angelos Tsiaras, a PhD student at UCL, who helped develop the new scanning technique. “This is a very exciting result because it’s the first time that we have been able to find the spectral fingerprints that show the gases present in the atmosphere of a super-Earth.”
Super-Earths are the most common type of planet in our galaxy, though none exist in our solar system. They are called super-Earths because they have more mass than Earth, but are smaller than the gas giants. A greater understanding of super-Earths should mean a greater understanding of the most common type of planet around.
“This result gives a first insight into the atmosphere of a super-Earth. We now have clues as to what the planet is currently like, how it might have formed and evolved, and this has important implications for 55 Cancri e and other super-Earths,” said Professor Giovanna Tinetti of UCL.
The existence of hydrogen cyanide in Janssen’s atmosphere is also significant. Its presence indicates a carbon-rich atmosphere. This supports the idea that Janssen is a diamond planet, though that conclusion is still far from certain. “If the presence of hydrogen cyanide and other molecules is confirmed in a few years time by the next generation of infrared telescopes, it would support the theory that this planet is indeed carbon rich and a very exotic place,” said Professor Jonathan Tennyson, UCL.
The team has used their new technique on 2 other super-Earths, but no atmosphere was found.
55-Cancri e is about 40 light years from Earth. Its host star is slightly smaller, cooler, and a little dimmer than our Sun, and its year is shorter than an Earth day.
If you try to apply simple common sense to how Saturn’s rings really work you’re going to be sorely mistaken: the giant planet’s signature features run circles around average Earthly intuition. This has been the case for centuries and is especially true now after recent news from Cassini that the most opaque sections of rings aren’t necessarily the densest; with Saturn looks literally are deceiving.
While rings are features shared by all of the gas and ice giant planets in our Solar System, Saturn is by far the “ring king” in terms of sheer magnitude, complexity, and utter beauty of its ring system. First observed through a telescope by Galileo in 1610, Saturn’s brilliant rings were initially thought by Galileo to be additional “stars,” or perhaps solid protrusions on either side of the planet like the handles of a cup. It wasn’t until 1659 that Dutch astronomer Christiaan Huygens determined that the handles were actually an encircling ring not attached to Saturn “but was separated from it the same distance all around.” (Source) And just sixteen years later Giovanni Cassini observed the largest gap in Saturn’s rings (which became his namesake feature) and correctly determined that they’re divided into sections.
While Galileo, Huygens, and Cassini all made invaluable contributions to the study of Saturn, they all assumed the rings to be solid. It was French astronomer Jean Chapelain who suggested in 1660 the rings must be made of tiny particles traveling in orbit around Saturn; however this wasn’t confirmed until the late 1850s when famed physicist James Clerk Maxwell calculated that, due to the forces of gravity and dynamical stability on such a large solid object, “the rings must consist of disconnected particles; these may be either solid or liquid, but they must be independent.” (Source)
Maxwell’s On the Stability of the Motion of Saturn’s Rings was published 100 years before Pioneer 11 gave us our first close-up views of Saturn. See a timeline of observations of Saturn’s rings here.
Fast forward to the present day.
In addition to countless observations from ground-based telescopes and space observatories like Hubble, Saturn has been flown past after Pioneer 11 by both Voyagers 1 and 2 and is currently being investigated by NASA’s Cassini spacecraft, which will soon enter its twelfth year of orbital exploration. Via the Cassini mission we’ve learned more about Saturn, its rings, and family of moons in the last decade than we had in the 394 years since Galileo first peered at it through his homemade telescope. And when it comes to its rings, researchers are learning what looks like more really is less.
Saturn’s incredibly complex ring system is divided up into distinct regions, named alphabetically outwards from the planet D, C, B, A, F, G, and E. (There’s also an enormous and diffuse infrared-visible ring surrounding Saturn at distance but we won’t get into that here.) All together these sections — each made up of bands of orbiting icy particles ranging from house-sized to finer than candle smoke — stretch a distance of 464,000 km (over 288,000 miles) from the top of Saturn’s atmosphere.. yet they’re only about ten meters (30 feet) thick.
One of Saturn’s ring sections — B — is much more visually opaque than the others, demonstrated both by its reflectivity and how it prevents light from background stars from easily passing through it as readily as in other rings. One might quickly conclude that such an apparently dense ring would therefore contain considerably more mass. Yet, as it turns out, that’s not the case.
Cassini measurements of density waves moving across the B ring in reaction to the gravitational pulls from nearby moons have given researchers the first accurate “weigh-in” of the ring’s core. What they found was a fairly consistent distribution of mass, regardless of any changes in opacity within the ring.
“At present it’s far from clear how regions with the same amount of material can have such different opacities. It could be something associated with the size or density of individual particles, or it could have something to do with the structure of the rings,” said Matthew Hedman in a Feb. 2 press release. Hedman is the recent study’s lead author and a Cassini participating scientist at the University of Idaho, Moscow.
And although the 25,500-kilometer-wide B ring likely does contain the most mass of all Saturn’s rings, it’s only by about a factor of two or three, despite being ten times more opaque than its outward A ring neighbor.
“Appearances can be deceiving,” noted co-investigator Phil Nicholson of Cornell University in Ithaca, New York. “A good analogy is how a foggy meadow is much more opaque than a swimming pool, even though the pool is denser and contains a lot more water.”
Makes sense. (Then again, your senses can fool you in astronomy!)
The actual mass of sections of Saturn’s rings is important in determining their age and evolution. Less material in the B ring than suspected may indicate a young age, since a “lighter” ring would evolve — and thus grow darker via meteorite impacts — quicker than a “heavier” one.
“By ‘weighing’ the core of the B ring for the first time, this study makes a meaningful step in our quest to piece together the age and origin of Saturn’s rings,” said Linda Spilker, Cassini project scientist at JPL.
Further measurements will be taken as Cassini goes into the final phase of its mission, eventually passing through the rings in 2017. The data it gathers along the way will help scientists more accurately calculate the mass and true age of the planet’s most iconic — and most enigmatic — features.
The astronomer known worldwide for vigorously promoting the demotion of Pluto from its decades long perch as the 9th Planet, has now found theoretical evidence for a new and very distant gas giant planet lurking at the far reaches of our solar system.
In a obvious reference to the planethood controversy, the proposed new planet is nicknamed ‘Planet Nine’ and its absolutely huge!
The possible planet has a mass about 10 times that of Earth and is believed to be gaseous, like Uranus and Neptune, according to Mike Brown of Caltech, who became famous during the contentious debate on Pluto’s planetary status. He announced the new finding today, Jan. 20, along with fellow Caltech researcher Konstantin Batygin.
The giant new planet orbits the sun some 20 times farther out than Neptune in the distant reaches of the Kuiper Belt. Neptune orbits the sun at an average distance of 2.8 billion miles.
Astronomers have been searching for decades for “Planet X” a large theorized planet beyond Pluto.
The theorized ‘Planet Nine’ travels in a highly elongated path that takes between 10,000 and 20,000 years to complete just one full orbit around the sun, according to Caltech statement describing the work.
Caltech astronomers Mike Brown and Konstantin Batygin coauthored a paper describing their work on the discovery of the existence of the proposed gas giant in the current issue of the Astronomical Journal.
The paper is titled; “EVIDENCE FOR A DISTANT GIANT PLANET IN THE SOLAR SYSTEM” and is available here.
“This would be a real ninth planet,” says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy, in a statement.
“There have only been two true planets discovered since ancient times, and this would be a third. It’s a pretty substantial chunk of our solar system that’s still out there to be found, which is pretty exciting.”
So far there is no confirmation of the existence of the planet.
It has not actually been observed but its existence is theorized through complex mathematical modeling and computer simulations.
Brown’s discovery of Eris in 2005, which orbits farther out than Pluto and is almost the same size as Pluto but smaller, sparked the IAU to demote Pluto to a dwarf planet in 2006.
Many planetary scientists, led by Alan Stern, do not agree with Pluto’s demotion.
Stern is the Principal Investigator of NASA’s New Horizons probe which carried out history’s first flyby of Pluto on July 14, 2015.
Among its numerous discoveries, New Horizons found that Pluto is a very geologically world even today and larger than Eris, and thus reigns as undisputed ‘King of the Kuiper Belt!”
In the Astronomical Journal paper, Batygin and Brown “show how Planet Nine helps explain a number of mysterious features of the field of icy objects and debris beyond Neptune known as the Kuiper Belt.”
“Although we were initially quite skeptical that this planet could exist, as we continued to investigate its orbit and what it would mean for the outer solar system, we become increasingly convinced that it is out there,” says Batygin, an assistant professor of planetary science.
“For the first time in over 150 years, there is solid evidence that the solar system’s planetary census is incomplete.”
In a prior interview, Alan Stern has told me that he believes that a planet at least as large as Mars lurks somewhere far out in the Kuiper Belt.
Meanwhile Batygin and Brown are hunting for ‘Planet Nine’ and they encourage others to search too.
Since they only know the rough orbit of the object, they continue to “refine their simulation” to better pin down its location to more productively aim the telescopes along the highly elliptical path.
“I would love to find it,” says Brown. “But I’d also be perfectly happy if someone else found it. That is why we’re publishing this paper. We hope that other people are going to get inspired and start searching.”
Here’s a comment from NASA’s Director of Planetary Sciences Jim Green, about today’s discovery:
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
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