NASA's Robonaut 2 (left) flashes a Star Trek Vulcan salutation along with George Takei, a star of the original series, in 2012. "It was a keen demonstration of Robonaut 2’s manual dexterity. The gesture is difficult for many humans to make," Takei wrote on Facebook. Credit: NASA/James Blair
Legs — yes, legs — are on the manifest for the next SpaceX Dragon flight. The commercial spacecraft is expected to blast off March 16 with appendenges for Robonaut 2 on board, allowing the humanoid to move freely around station. After some initial tests in June will come R2’s first step, marking a new era in human spaceflight.
What’s exciting about R2 is not only its ability to take over simple tasks for the astronauts in station, but in the long run, to head “outside” to do spacewalks. This would greatly reduce risk to the astronauts, as extravehicular activity is one of the most dangerous things you can do outside (as a spacesuit leak recently reminded us.)
When installed, Robonaut will have a “fully extended leg span” of nine feet (wouldn’t we love to see the splits with that). Instead of a foot, each seven-jointed leg will have an “end effector” that is a sort of clamp that can grab on to things for a grip. It’s similar to the technology used on the Canadarm robotic arm, and also like Canadarm, there will be a vision system so that controllers know where to grasp.
NASA Expedition 35 astronaut Tom Marshburn (background) performs teleoperation activitites with Robonaut 2 aboard the International Space Station in 2013. Credit: NASA
The robot first arrived on station in February 2011 and (mostly while tied down) has done a roster of activities, such as shake hands with astronaut Dan Burbank in 2012 (a humanoid-human first in space), say hello to the world with sign language, and do functions such as turn knobs and flip switches. During Expedition 34/35 in 2012-13, astronaut Tom Marshburn even made Robonaut 2 catch a free-floating object through teleoperation.
Eventually NASA expects to use the robot outside the station, but more upgrades to Robonaut 2’s upper body will be needed first. The robot could then be used as a supplement to spacewalks, which are one of the most dangerous activities that humans do in space.
Closer to Earth, NASA says the technology has applications for items such as exoskeletons being developed to help people with physical disabilities.
NASA’s Robonaut 2 with “climbing legs” intended to let the robot rove around in the microgravity environment aboard the International Space Station. This version is being tested on the ground for eventual use in space. Credit: NASAR2A waving goodbye. Robonaut R2A waving goodbye as Robonaut R2B launches into space aboard STS-133 from the Kernnedy Space Center. R2 is the first humanoid robot in space. Credit: Joe Bibby
It’s a tough old universe out there. A young star has lots to worry about, as massive stars just beginning to shine can fill a stellar nursery with a gale of solar wind.
No, it’s not a B-movie flick: the “Death Stars of Orion” are real. Such monsters come in the form of young, O-type stars.
And now, for the first time, a team of astronomers from Canada and the United States have caught such stars in the act. The study, published in this month’s edition of The Astrophysical Journal, focused on known protoplanetary disks discovered by the Hubble Space Telescope in the Orion Nebula.
These protoplanetary disks, also known as “tadpoles” or proplyds, are cocoons of dust and gas hosting stars just beginning to shine. Much of this leftover material will go on to aggregate into planets, but nearby massive O-Type stars can cause chaos in a stellar nursery, often disrupting the process.
“O-Type stars, which are really monsters compared to our Sun, emit tremendous amounts of ultraviolet radiation and this can play havoc during the development of young planetary systems,” said astronomer Rita Mann in a recentpress release. Mann works for the National Research Council of Canada in Victoria and is lead researcher on the project
Scientists used the Atacama Large Millimeter Array (ALMA) to probe the proplyds of Orion in unprecedented detail. Supporting observations were also made using the Submillimeter Array in Hawaii.
ALMA saw “first light” in 2011, and has already achieved some first rate results.
“ALMA is the world’s most sensitive telescope at high-frequency radio waves (e.g., 100-1000 GHz). Even with only a fraction of its final number of antennas, (with 22 operational out of a total planned 50) we were able to detect with ALMA the disks relatively close to the O-star while previous observatories were unable to spot them,” James Di Francesco of the National Research Council of Canada told Universe Today. “Since the brightness of a disk at these frequencies is proportional to its mass, these detections meant we could measure the masses of the disks and see for sure that they were abnormally low close to the O-type star.”
The ALMA antennae on the barren plateau of Chajnantor. Credit: ALMA (ESO/NAOJ/NRAO).
ALMA also doubled the number of proplyds seen in the region, and was also able to peer within these cocoons and take direct mass measurements. This revealed mass being stripped away by the ultraviolet wind from the suspect O-type stars. Hubble had been witness to such stripping action previous, but ALMA was able to measure the mass within the disks directly for the first time.
And what was discovered doesn’t bode well for planetary formation. Such protostars within about 0.1 light-years of an O-type star are consigned to have their cocoon of gas and dust stripped clean in just a few million years, just a blink of a eye in the game of planetary formation.
With a O-type star’s “burn brightly and die young” credo, this type of event may be fairly typical in nebulae during early star formation.
“O-type stars have relatively short lifespan, say around 1 million years for the brightest O-star in Orion – which is 40 times the mass of our Sun – compared to the 10 billion year lifespan of less massive stars like our Sun,” Di Francesco told Universe Today. “Since these clusters are typically the only places where O-stars form, I’d say that this type of event is indeed typical in nebulae hosting early star formation.”
It’s common for new-born stars to be within close proximity of each other in such stellar nurseries as M42. Researchers in the study found that any proplyds within the extreme-UV envelope of a massive star would have its disk shredded in short order, retaining on average less than 50% the mass of Jupiter total. Beyond the 0.1 light year “kill radius,” however, the chances for these proplyds to retain mass goes up, with researchers observing anywhere from 1 to 80 Jupiter masses of material remaining.
The findings in this study are also crucial in understanding what the early lives of stars are like, and perhaps the pedigree of our own solar system, as well as how common – or rare – our own history might be in the story of the universe.
There’s evidence that our solar system may have been witness to one or more nearby supernovae early in its life, as evidenced by isotopic measurements. We were somewhat lucky to have had such nearby events to “salt” our environment with heavy elements, but not sweep us clean altogether.
“Our own Sun likely formed in a clustered environment similar to that of Orion, so it’s a good thing we didn’t form too close to the O-stars in its parent nebula,” Di Francesco told Universe Today. “When the Sun was very young, it was close enough to a high-mass star so that when it blew up (went supernova) the proto-solar system was seeded with certain isotopes like Al-26 that are only produced in supernova events.”
This is the eventual fate of massive O-type stars in the Orion Nebula, though none of them are old enough yet to explode in this fashion. Indeed, it’s amazing to think that peering into the Orion Nebula, we’re witnessing a drama similar to what gave birth to our Sun and solar system, billions of years ago.
The Orion Nebula is the closest active star forming region to us at about 1,500 light years distant and is just visible to the naked eye as a fuzzy patch in the pommel of the “sword” of Orion the Hunter. Looking at the Orion Nebula at low power through a small telescope, you can just make out a group of four stars known collectively as the Trapezium. These are just such massive hot and luminous O-Type stars, clearing out their local neighborhoods and lighting up the interior of the nebula like a Chinese lantern.
And thus science fact imitates fiction in an ironic twist, as it turns out that “Death Stars” do indeed blast planets – or at least protoplanetary disks – on occasion!
Be sure to check out a great piece on ALMA on a recent episode of CBS 60 Minutes:
Read the abstract and the full (paywalled) paper on ALMA Observations of the Orion Proplyds in The Astrophysical Journal.
It’s a staple of science fiction, restarting our dying star with some kind of atomic superbomb. Why is our Sun running out of fuel, and what can we actually do to get it restarted?
Stars die. Occasionally threatening the Earth and its civilization in a variety plot devices in science fiction. Fortunately there’s often a Bruce Willis coming in to save the day, delivering a contraption, possibly riding a giant bomb shaped like a spaceship, to the outer proximity of our dying Sun that magically fixes the broken star and all humanity is saved.
Is there any truth in this idea? If our Sun dies, can we just crack out a giant solar defibrillator and shock it back into life? Not exactly.
First, let’s review at how stars die. Our Sun is halfway through its life. It’s been going for about 4.5 billion years, and in 5 billion years it’ll use up all the hydrogen in its core, bloat up as a red giant, puff off its outer layers and collapse down into a white dwarf.
Is there a point in there, anywhere, that we could get it back to acting like a sun? Technically? Yes. Did you know it will only use up a fraction of its fuel during its lifetime? Only in the core of the Sun are the temperatures and pressures high enough for fusion reactions to take place. This region extends out to roughly 25% of the radius, which only makes up about 2% of the volume.
Outside the core is the radiative zone, where fusion doesn’t take place. Here, the only way gamma radiation can escape is to be absorbed and radiated countless times, until it reaches the next layer of the Sun: the convective zone. Here temperatures have dropped to the point that the whole region acts like a giant lava lamp. Huge blobs of superheated stellar plasma rise up within the star and release their energy into space. This radiative zone acts like a wall, keeping the potential fuel in the convective zone away from the fusion furnace.
Cutaway to the Interior of the Sun. Credit: NASA
So, if you could connect the convective zone to the solar core, you’d be able to keep mixing up the material in the Sun. The core of the Sun would be able to efficiently fuse all the hydrogen in the star.
Sound crazy? Interestingly, this already happens in our Universe. For red dwarf stars with less than 35% the mass of the Sun, their convective zones connect directly to the core of the star. This is why these stars can last for hundreds of billions and even trillions of years. They will efficiently use up all the hydrogen in the entire star thanks to the mixing of the convective zone. If we could create a method to break through the radiative zone and get that fresh hydrogen into the core of the Sun, we could keep basking in its golden tanning rays for well past its current expiration date.
I never said it would be easy. It would take stellar engineering at a colossal scale to overcome the equilibrium of the star. A future civilization with an incomprehensible amount of energy and stellar engineering ability might be able to convert our one star into a collection of fully convective red dwarf stars. And these could sip away their hydrogen for trillions of years.
Tell us in the comments on how you think we should go about it. My money is on giant ‘magic bullet’ blender” or a perhaps a Dyson solar juicer.
Hydrothermal vents deep in Earth's oceans. Could similar types of vents power the transport of silica and other materials out from Enceladus? Credit: NOAA
When it comes to life on Earth, we’re not sure if it came from the outside (transported by comets) or on the inside. A new theory focuses on the “interior ” theory, saying that microbes could have evolved from non-living matter such as chemical compounds in minerals and gases.
“Before biological life, one could say the early Earth had ‘geological life’. It may seem unusual to consider geology, involving inanimate rocks and minerals, as being alive. But what is life?” stated Terry Kee, a biochemist at the University of Leeds in the United Kingdom who participated in the research.
“Many people have failed to come up with a satisfactory answer to this question. So what we have done instead is to look at what life does, and all life forms use the same chemical processes that occur in a fuel cell to generate their energy.”
When thinking of a car, the research team says, they point out that fuel cells create electrical energy through the reaction of fuels and oxidants. This is called a “redox reaction”, which takes place when a molecule loses electrons and another molecule gains them.
In plants, photosynthesis creates electrical energy when carbon dioxide breaks down into sugars, and water is oxidized into molecular oxygen. (By contrast, humans oxidize sugars into carbon dioxide and break down the oxygen into water — another electrical energy process.)
Now, let’s go a step further. Hydrothermal vents are hot geysers on the sea floor that are often considered an interesting spot for life studies. They host “extremophiles”, or forms of life that exist (“thrive” is the better word) despite a harsh environment. The researchers say these vents are a sort of “environmental fuel cell” because electrical energy is generated from redox reactions between seawater oxidants and hydrothermal vents.
And this is where the new research comes in. At the University of Leeds and NASA’s Jet Propulsion Laboratory, the researchers put iron and nickel in the place of the usual “platinum catalysts” found in fuel cells and electrical experiments.
Rendering showing the location and size of water vapor plumes coming from Europa’s south pole.
While the power was reduced, electricity did indeed flow. And while researchers still don’t know how non-life could have transformed into life, they say this is another step to understanding what happened. What’s more, it could be useful for future trips to other planets.
“These experiments simulate the electrical energy produced in geological systems, so we can also use this to simulate other planetary environments with liquid water, like Jupiter’s moon Europa or early Mars,” stated Laura Barge, a researcher from the NASA Astrobiology Institute* who led the research.
“With these techniques we could actually test whether any given hydrothermal system could produce enough energy to start life, or even, provide energetic habitats where life might still exist and could be detected by future missions.”
Artist's conception of the Milky Way galaxy. Credit: Nick Risinger
Is it stretching it too far to think of a Lord of the Rings-esque “Entmoot” when reading the phrase “Council of Giants”? In this case, however, it’s not trees gathering in a circle, but galaxies.
A new map of the galactic neighborhood shows how the Milky Way may be restricted by a bunch of galaxies surrounding and constricting us with gravity.
“All bright galaxies within 20 million light years, including us, are organized in a ‘Local Sheet’ 34-million light years across and only 1.5 million light years thick,” stated Marshall McCall of York University in Canada, who is the sole author of a paper on the subject.
“The Milky Way and Andromeda are encircled by twelve large galaxies arranged in a ring about 24-million light years across. This ‘Council of Giants’ stands in gravitational judgment of the Local Group by restricting its range of influence.”
The “Council of Giants” is shown in this diagram based on 2014 research from York University. It shows the brightest galaxies within 20 million light-years of the Milky Way. The galaxies in yellow are the “Council.” (You can see a larger image if you click on this.) Credit: Marshall McCall / York University.
Here’s why McCall thinks this is the case. Most of the Local Sheet galaxies (the Milky Way, Andromeda, and 10 more of the 14 galaxies) are flattened spiral galaxies with stars still forming. The other other two galaxies are elliptical galaxies where star-forming ceased long ago, and of note, this pair lie on opposite sides of the “Council.”
“Winds expelled in the earliest phases of their development might have shepherded gas towards the Local Group, thereby helping to build the disks of the Milky Way and Andromeda,” the Royal Astronomical Society stated. The spin in this group of galaxies, it added, is unusually aligned, which could have occurred due to the influence of the Milky Way and Andromeda “when the universe was smaller.”
The larger implication is the Local Sheet and Council likely came to be in “a pre-existing sheet-like foundation composed primarily of dark matter”, or a mysterious substance that is not measurable by conventional instruments but detectable on how it influences other objects. McCall stated that on a small scale, this could help us understand more about how the universe is constructed.
Looped movie of the hydrogen jet in the sample chamber. Credit: Sven Toleikis/DESY
In astronomy we love focusing on the bigger picture. We’re searching for exoplanets in the vast hope that we may begin to paint a picture of how planetary systems form; We’re using the Hubble Space Telescope to peer into the earliest history of the cosmos; And we’re building gravitational wave detectors in order to better understand the physical laws that dominate our universe.
All the while we continue to learn about our very own neighborhood. Only recently we learned that Europa has geysers, Mars was perhaps once a lush planet, and comets can in fact disintegrate. Discoveries in our solar system alone never cease to amaze.
For the first time researchers are able to probe the hidden interiors of gas giants such as Jupiter and Saturn. With very little experimental knowledge about the hydrogen deep within such planets, we have always had to rely on mathematical models. But now, researchers have simulated the lower atmospheric layers of these planets in the lab.
The team of physicists led by Dr. Ulf Zastrau from the University of Jena heated cold liquid hydrogen to resemble the dense liquid hydrogen deep within a gas giant’s atmospheric layers.
The team used an X-ray laser operated by a national research center in Germany, Deutsches Elektronen-Synchrotron (DESY), to heat the liquid hydrogen, nearly instantaneously, from -253 to +12,000 degrees Celsius. Initially the X-ray heats only the electrons. But because each electron is bound to a proton, they transfer heat to the proton until a thermal equilibrium is reached. The molecular bonds break during this process, and a plasma of electrons and protons is formed.
In just under a trillionth of a second, physicists are able to create a plasma that’s thought to be radically similar to the plasma deep within the atmospheres of our beloved gas giants.
But first the team had to create cold hydrogen. While it’s abundant throughout the universe, it’s hard to get our hands on the stuff here on Earth. Instead researchers cooled gaseous hydrogen to -253 degrees Celsius using liquid helium. This was a very temperamental process, requiring precise temperature control. If the hydrogen got too cold it would freeze and the researchers would have to use a small heater to re-liquefy it. At the end of the day a jet of cold liquid hydrogen with a diameter no greater than 20 micrometers would flow into a vacuum.
Physicists would then shoot intense pulses of the X-ray laser at the cold hydrogen. They could control the precise timing of the X-ray laser’s “flash” in order to study the properties of liquid hydrogen. The first half of the flash heats up the hydrogen, but the second half of the flash is delayed by varying lengths, which allows the team to understand exactly how thermal equilibrium is established between the electrons and the protons.
The experimental results provide information on the liquid hydrogen’s thermal conductivity and its internal energy exchange, which are both crucial to better understanding gas giants. The experiments will have to be repeated at other temperatures and pressures in order to create a detailed picture of the entire planetary atmosphere.
“Hopefully the results will provide us among others with an experimentally based answer to the question, why the planets discovered outside our solar system do not exist in all imaginable combinations of properties as age, mass, size or elemental composition, but may be allocated to certain groups,” said Dr. Thomas Tschentscher, scientific director of the European XFEL X-ray laser in a press release.
The paper has been accepted in the scientific journal Physical Review Letters and is available for download here.
Artist's impression of a satellite exploding. Credit: ESA
What happens to a battery in a dead satellite? Despite nearly 60 years of sending these machines into space, this is a “relative blind spot” among designers, the European Space Agency says. And that’s a big problem, because there’s a chance that these power sources can rupture and cause debris — adding to the growing problem in orbit.
With NASA estimating more than 500,000 dead satellites and other debris cluttering up the environment around Earth, the risk of something smashing into an important space thing — a spacecraft, a GPS satellite, a weather monitor — increases. So space policy-makers are doing what they can to reduce the problem (while also creating methods to clean it up.)
A few satellite breakups in the ’90s were linked to battery failures, but ESA notes these were older, non-lithium types. To figure out what’s happened more recently, the agency wants to learn more about battery behavior after the satellite shuts down, and how to prevent a breakup from happening.
“As a satellite drifts freely, could batteries endure the harsh environment of orbit – including wild temperature swings, degradation of thermal control and components as well as radiation exposure – without leakage or bursting?” ESA asks.
Artist’s impression of debris in low Earth orbit. Credit: ESA
For more information, go to the ESA tendering website and look for solicitation AO7840, called “Spacecraft Power System Passivation At End Of Mission.” The tender is valued between 200,000 and 500,000 Euros and closes April 23.
“The goal of the activity is to study and implement the most adequate means to achieve this power system passivation,” the tender states.
“This may involve the discharge and disconnection of the batteries and the disconnection of the solar arrays. This passivation needs to be reliable enough to avoid to deactivate the power system before the end of the mission. The proposed concept should be universal enough to be compatible with most space applications (but in priority European institutional market).”
Satellite image of suspected floating objects from the missing Malaysia Airlines plane MH 370. Credit: China SASTIND/China Resources Satellite Application Center
Chinese satellite image of suspected floating objects from the missing Malaysia Airlines plane MH 370. Credit: China SASTIND/China Resources Satellite Application Center See more satellite imagery below[/caption]
Chinese government satellites orbiting Earth may have detected floating, crash related debris from the missing Malaysian Airline flight MH-370 that disappeared without a trace last week – and which could be a key finding in spurring the ongoing and so far fruitless search efforts.
Today, Wednesday, March 12, Chinese space officials released a trio of images that were taken by Chinese satellites on Sunday, March 9, showing the possible crash debris in the ocean waters between Malaysia and Vietnam.
China’s State Administration of Science, Technology and Industry for National Defence (SASTIND) posted the images on its website today, although they were taken on Sunday at about 11 a.m. Beijing local time.
I found the images today directly on SASTIND’s Chinese language website and they are shown here in their full resolution – above and below.
The Boeing 777-200ER jetliner went missing on Saturday on a flight en route from Kuala Lampur, Malaysia to Beijing, China.
The images appear to show “three floating objects in the suspected site of missing Malaysian plane,” according to SASTIND.
Satellite image of suspected floating objects from the missing Malaysia Airlines plane MH 370. Credit: China SASTIND/China Resources Satellite Application Center
The plane carrying 227 passengers and 12 crew members mysteriously lost radio contact and vanished from radar while flying over the South China Sea. The transponder stopped sending signals.
And not a trace of the jetliner has been found despite days of searching by ships and planes combing a vast search area that expands every day.
Smaller versions of the satellites images and a video report have also been posted on China’s government run Xinhua and CCTV news agencies.
The three suspected floating objects measure 13 by 18 meters (43 by 59 feet), 14 by 19 meters (46 by 62 feet) and 24 by 22 meters (79 feet by 72 feet).
Chinese satellite image of suspected floating objects from the missing Malaysia Airlines plane MH 370. Credit: China SASTIND/China Resources Satellite Application Center
These suspected debris are surprising large, about the size of the jetliners wing, according to commentators speaking tonight on NBC News and CNN.
SASTIND said that “the three suspected objects were monitored at 6.7 degrees north latitude and 105.63 degrees east longitude, spreading across an area with a radius of 20 kilometers, according to Xinhua.
These coordinates correspond with the ocean waters between Malaysia and Vietnam, near the expected flight path.
“Some 10 Chinese satellites have been used to help the search and rescue operation,” reported CCTV.
Photo of Malaysia Air Boeing 777-200
China, the US, Malaysia and more than a dozen counties are engaged in the continuing search and rescue effort that has yielded few clues and no answers for the loved ones of the missing passengers and crew on board. Our hearts and prayers go out to them.
The search area currently encompasses over 35,000 nautical square miles.
Ships and planes are being dispatched to the location shown by the new satellite imagery to help focus the search effort and find the black boxes recording all the critical engineering data and cockpit voices of the pilot and copilot and aid investigators as to what happened.
No one knows at this time why the Malaysia Airlines flight mysteriously disappeared.
Artist's impression of the asteroid belt. Image credit: NASA/JPL-Caltech
When you think of the asteroid belt, you probably imagine a region of rock and dust, with asteroids as far as the eye can see. Such a visual has been popularized in movies, where spaceships must swerve left and right to avoid collisions. But a similar view is often portrayed in more scientific imagery, such as the artistic rendering above. Even the first episode of the new Cosmos series portrayed the belt as a dense collection of asteroids. But the reality is very different. In reality the asteroid belt is less cluttered than often portrayed. Just how much less might surprise you.
The Sloan digital sky survey (SDSS) has identified more than 100,000 asteroids in the solar system. Not all of these lie within the asteroid belt, but there are about 80,000 asteroids in the belt larger than a kilometer. Of course there are asteroids smaller than that, but they are more difficult to detect, so we aren’t exactly sure how many there are.
The pyramid-shaped zodiacal light cone is centered on the same path the sun and planets take across the sky called the ecliptic. This map shows the sky 90 minutes after sunset in early March facing west. Created with Stellarium
We have a pretty good idea, however, because the observations we have indicate that the size distribution of asteroids follows what is known as a power law distribution. For example, with a power law of 1, for every 100-meter wide asteroid there would be 10 with a diameter of 10 meters and 100 with a diameter of 1 meter. Based upon SDSS observations, asteroids seem to follow a power law of about 2, which means there are likely about 800 trillion asteroids larger than a meter within the belt. That’s a lot of rock. So much that sunlight scattering off the asteroid belt and other dust in the solar system is the source of zodiacal light.
But there is also a lot of volume within the asteroid belt. The belt can be said to occupy a region around the Sun from about 2.2 to 3.2 times the distance from the Earth to the Sun from the Sun (AU), with a thickness of about 1 AU. A bit of math puts that at about 50 trillion trillion cubic kilometers. So even though there are trillions of asteroids, each asteroid has billions of cubic kilometers of space on average. The asteroid belt is hardly something you would consider crowded. It should be emphasized that asteroids in the belt are not evenly distributed. They are clustered into families and groups. But even such clustering is not significant compared to the vast space it occupies.
An actual image from within the asteroid belt, taken from the NEAR probe as it was heading toward Eros (center). Credit: NASA
You can even do a very rough calculation to get an idea of just how empty the asteroid belt actually is. If we assumed that all the asteroids lay within a single plane, then on average there is 1 asteroid within an area roughly the size of Rhode Island. Within the entire United States there would be about 2000 asteroids, most of them only a meter across. The odds of seeing an asteroid along a cross-country road trip, much less hitting one, would be astoundingly small. So you can see why we don’t worry about space probes hitting an asteroid on their way to the outer solar system. In fact, to get even close to an asteroid takes a great deal of effort.
No "Planet X" was found in a survey of the sky using NASA's Wide-Field Infrared Survey Explorer. This picture, which comes from the same dataset, shows a recently discovered star (in red) called WISEA J204027.30+695924.1. Credit: DSS/NASA/JPL-Caltech
It’s one of those rumors that just won’t quiet down — a large planet lurking at the solar system’s edge. Back in the 1840s, when Neptune was discovered, its orbit seemed to be a little “off” from what was expected.
Some astronomers of the time said that was caused by a planet further out. Although the Neptune perturbations are now ascribed to observational errors, the tale of Planet X continues, and has sometimes even been linked with doomsday. (See this past Universe Today story for the full tale.)
NASA’s latest survey puts even less credence in that theory. A scan of the sky showed nothing Saturn’s size or bigger at a distance of 10,000 Earth-sun distances, or astronomical units. Nothing bigger than Jupiter exists as far as 26,000 AU. (To put that in perspective, Pluto is 40 AU from the sun.)
“The outer solar system probably does not contain a large gas giant planet, or a small, companion star,” stated Kevin Luhman of the Center for Exoplanets and Habitable Worlds at Penn State University, author of a paper in the Astrophysical Journal describing the results.
Astronomers used information from NASA’s Wide-Field Infrared Survey Explorer, which did two full-sky scans in 2010 and 2011 to look at asteroids, stars and galaxies. NASA’s AllWISE program, released in November 2013, allows astronomers to find moving objects by comparing the two surveys.
Artist’s impression of the WISE satellite
A second study of the data found other objects further out in space — 3,525 stars and brown dwarfs (objects just below the threshold for fusion) within 500 light-years of the sun.
“We’re finding objects that were totally overlooked before,” stated Davy Kirkpatrick of NASA’s Infrared and Processing Analysis Center at the California Institute of Technology, who led the second paper.
Both papers will be published in the Astrophysical Journal.
