The Helix nebula is visible in the center of this image, surrounded by tracks of asteroids that are much closer to Earth (yellow dots). Click on the image to see them. The streaks you see are from satellites or cosmic rays. Credit: NASA/JPL-Caltech/UCLA
Besides being a darn pretty picture of the Helix nebula, this snapshot is a bit of symbolism for NASA. The spacecraft that nabbed this view is called the Wide-field Infrared Survey Explorer, or WISE. If you look very carefully — you may have to click on the picture for a closer view — you can see little dots showing the paths of asteroids in the picture. (The streaks are cosmic rays and satellites.)
WISE has an interesting history. It began as a telescope seeking secrets of the universe in infrared light, but ran out of coolant in 2010 and was repurposed for asteroid searching under the NEOWISE mission. It wrapped up its mission, was put into hibernation in February 2011, then reactivated this August to look for asteroids again for at least the next three years. You can see some pictures and data WISE collected during its mission below the jump.
It’s a nice way, NASA said, to celebrate the fourth anniversary of WISE’s launch. “WISE is the spacecraft that keeps on giving,” said Ned Wright of UCLA, who was the principal investigator of WISE before it transitioned into NEOWISE.
Results from NASA’s NEOWISE survey find that more potentially hazardous asteroids, or PHAs, are closely aligned with the plane of our solar system than previous models suggested. Image credit: NASA/JPL-CaltechThis enormous section of the Milky Way galaxy is a mosaic of images from NASA’s Wide-field Infrared Survey Explorer, or WISE. The constellations Cassiopeia and Cepheus are featured in this 1,000-square degree expanse. Image credit: NASA/JPL-Caltech/UCLAThis oddly colorful nebula is the supernova remnant IC 443 as seen by WISE. Image credit: NASA/JPL-Caltech/UCLA
Artist's conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech
Exoplanets are really tiny compared to their host star, and it’s hard to imagine sometimes how astronomers can even find one of these worlds — let alone thousands of them. This nifty two-part series from PBS explains how it’s possible in an easy-to-understand and hilarious way. As an example, this is how they describe the Kepler space telescope’s capabilities:
“It can’t actually see those exoplanets because the stars that they surround are so big and bright. Instead, it looks for the tiny shadow of the planet as it passes in front of its parent star. If that sounds hard, that’s because it is. It’s like seeing a flea in a lightbulb in Los Angeles from New York City,” said host Joe Hanson in the video.
Near the end, he provides an interesting segway into the question of life beyond Earth: “The question we’re really interested in is not how common are planets, but how common are we.” That gets tackled in part 2 of the video, which you can see below the jump.
Remember that 2014 will be an interesting year for Kepler as NASA figures out what to do next with the observatory. It isn’t able to perform its primary mission (seeking exoplanets in Cygnus) because two of its four reaction wheels or pointing devices are malfunctioning. NASA, however, has an innovative fix on the books that could allow it to swing different fields of view during the year — check out this infographic for more details.
Fast radio bursts — eruptions of extreme energy that occur only once and last a thousandth of a second — are continuing to defy astronomers. At first observations suggested they came from billions of light years away. A new study, however, points to sources much closer to home: nearby flaring stars.
“We have argued that fast radio burst sources need not be exotic events at cosmological distances, but rather could be due to extreme magnetic activity in nearby Galactic stars,” said Harvard professor Abraham Loeb in the study.
All radio bursts show a dispersion measure — a frequency dependent time delay — as the long-wavelength component arrives a fraction of a second after the short-wavelength component. When the burst travels through a medium, the long-wavelength component moves slightly slower than short-wavelength component.
This dispersion may easily be created when light travels through intergalactic space. The farther the light travels, the more electrons it will have to travel through, and the greater time delay between the arriving wavelength components.
With this assumption, fast radio bursts are likely to have originated anywhere from five to 10 billion light years away. Universe Today covered an extra-galactic origin a few months ago (read it here).
However, Loeb and his colleagues turned their eyes instead to electrons in stellar corona. These electrons are tightly packed, more so than diffuse intergalactic electrons, and would create the same observable effect.
Flaring stars — variable stars that can undergo unpredictable increases in brightness — are a likely source of fast radio bursts. Two circumstances may create flaring stars: young, low mass stars and solar-mass contact binaries, which orbit so close to one another that they share a common envelope.
In order to test this theory, Loeb and his colleagues searched the vicinities of three of the six known fast radio bursts for flaring stars.
“We were surprised that, apparently, no one had done this before,” said graduate student Yossi Shvartzvald in a press release. Shvartzvald led the observations at Tel-Aviv University’s Wise Observatory in Mitspe Ramon, Israel.
The team discovered a contact binary system in one location. Two sun-like stars orbit one another every 7.8 hours. They calculate a five percent chance that the contact binary is there by coincidence.
No flaring stars, however, were detected in the two other fields.
“Whenever we find a new class of sources, we debate whether they are close or far away,” Loeb said in a press release. Initially we thought gamma-ray bursts were faint stars within the Milky Way. Today we know they are bright explosions in distant galaxies.
It seems the distance debate for fast radio bursts has only begun.
The paper has been accepted for publication in the Monthly Notices of the Royal Astronomical Society and is available for download here. The original press release may be found here.
Messier 1 Hubble Image: Credit - NASA, ESA, J. Hester and A. Loll (Arizona State University)
There are only six of them: radon, helium, neon, krypton, xenon and the first molecules to be discovered in space – argon. They are all odorless, colorless, monatomic gases with very low chemical reactivity. So where did a team of astronomers using ESA’s Herschel Space Observatory make their rather unusual discovery? Try Messier 1… The “Crab” Nebula!
In a study led by Professor Mike Barlow (UCL Department of Physics & Astronomy), a UCL research team was taking measurements of cold gas and dust regions of this famous supernova remnant in infrared light when they stumbled upon the chemical signature of argon hydrogen ions. By observing in longer wavelengths of light than can be detected by the human eye, the scientists gave credence to current theories of how argon occurs naturally.
“We were doing a survey of the dust in several bright supernova remnants using Herschel, one of which was the Crab Nebula. Discovering argon hydride ions here was unexpected because you don’t expect an atom like argon, a noble gas, to form molecules, and you wouldn’t expect to find them in the harsh environment of a supernova remnant,” said Barlow.
When it comes to a star, they are hot and ignite the visible spectrum. Cold objects like nebular dust are better seen in infrared, but there’s only one problem – Earth’s atmosphere interferes with the detection of that end of the electromagnetic spectrum. Even though we can see nebulae in visible light, what shows is the product of hot, excited gases, not the cold and dusty regions. These invisible regions are the specialty of Herschel’s SPIRE instruments. They map the dust in far-infrared with their spectroscopic observations. In this instance, the researchers were somewhat astounded when they found some very unusual data which required time to fully understand.
“Looking at infrared spectra is useful as it gives us the signatures of molecules, in particular their rotational signatures,” Barlow said. “Where you have, for instance, two atoms joined together, they rotate around their shared center of mass. The speed at which they can spin comes out at very specific, quantized, frequencies, which we can detect in the form of infrared light with our telescope.”
According to the news release, elements can exist in varying forms known as isotopes. These have different numbers of neutrons in the atomic nuclei. When it comes to properties, isotopes can be somewhat alike to each other, but they have different masses. Because of this, the rotational speed is dependent on which isotopes are present in a molecule. “The light coming from certain regions of the Crab Nebula showed extremely strong and unexplained peaks in intensity around 618 gigahertz and 1235 GHz.” By comparing data of known properties of different molecules, the science team came to the conclusion the mystery emission was the product of spinning molecular ions of argon hydride. What’s more, it could be isolated. The only argon isotope which could spin like that was argon-36! It would appear the energy released from the central neutron star in the Crab Nebula ionized the argon, which then combined with hydrogen molecules to form the molecular ion ArH+.
Professor Bruce Swinyard (UCL Department of Physics & Astronomy and Rutherford Appleton Laboratory), a member of the team, added: “Our discovery was unexpected in another way — because normally when you find a new molecule in space, its signature is weak and you have to work hard to find it. In this case it just jumped out of our spectra.”
Is this instance of argon-36 in a supernova remnant natural? You bet. Even though the discovery was the first of its kind, it is doubtless not the last time it will be detected. Now astronomers can solidify their theories of how argon forms. Current predictions allow for argon-36 and no argon-40 to also be part of supernova structure. However, here on Earth, argon-40 is a dominant isotope, one which is created through the radioactive decay of potassium in rocks.
Noble gas research will continue to be a focus of scientists at UCL. As an amazing coincidence, argon, along with other noble gases, was discovered at UCL by William Ramsay at the end of the 19th century! I wonder what he would have thought had he known just how very far those discoveries would take us?
Original Story Source: University College London (UCL) Press Release
This colorized mosaic from NASA's Cassini mission shows the most complete view yet of Titan's northern land of lakes and seas. Saturn's moon Titan is the only world in our solar system other than Earth that has stable liquid on its surface. The liquid in Titan's lakes and seas is mostly methane and ethane. Image credit: NASA/JPL-Caltech/ASI/USGS
Saturn’s moon Titan has the only known liquid lakes beyond planet Earth, and new data from the Cassini spacecraft’s radar instrument provides an intriguing 3-D flyover of these hydrocarbon lakes and seas at the north pole region. Steve Wall, Cassini acting radar team lead, provided a guided tour as he presented the video at the American Geophysical Union conference in San Francisco, noting that the vertical heights are exaggerated tenfold and the data has been colorized, both for visual effect.
The video starts by zooming into the southern end of Kraken Mare, the largest of Titan’s seas, and as you fly a little farther, Wall said the things that look like little islands are just noise in the radar data. Next, comes Ligea Mare, with its rugged coastline, and you’ll see that the liquid flow into the surrounding terrain, which appear like river valleys.
The “smooth” area that stretches farther from Ligea Mare is actualy not so smooth, but is just an area when the science team doesn’t have topographical data yet.
The video then continues to other smaller lakes that are nestled into valleys and rugged terrain.
“Learning about surface features like lakes and seas helps us to understand how Titan’s liquids, solids and gases interact to make it so Earth-like,” said Wall. “While these two worlds aren’t exactly the same, it shows us more and more Earth-like processes as we get new views.”
The new data is not only visually stunning, but provides previously unknown details about these lakes and the region. For example, Kraken Mare is more extensive and complex than previously thought. They also show nearly all of the lakes on Titan fall into an area covering about 600 miles by 1,100 miles (900 kilometers by 1,800 kilometers). Only 3 percent of the liquid at Titan falls outside of this area.
“Scientists have been wondering why Titan’s lakes are where they are. These images show us that the bedrock and geology must be creating a particularly inviting environment for lakes in this box,” said Randolph Kirk, a Cassini radar team member at the U.S. Geological Survey in Flagstaff, Ariz. “We think it may be something like the formation of the prehistoric lake called Lake Lahontan near Lake Tahoe in Nevada and California, where deformation of the crust created fissures that could be filled up with liquid.”
Additionally, scientists now know that Ligeia Mare is about 560 feet (170 meters) deep. This is the first time scientists have been able to plumb the bottom of a lake or sea on Titan. This was possible partly because the liquid turned out to be very pure, allowing the radar signal to pass through it easily. The liquid surface may be as smooth as the paint on our cars, and it is very clear to radar eyes.
“Ligeia Mare turned out to be just the right depth for radar to detect a signal back from the sea floor, which is a signal we didn’t think we’d be able to get,” said Marco Mastrogiuseppe, a Cassini radar team associate at Sapienza University of Rome. “The measurement we made shows Ligeia to be deeper in at least one place than the average depth of Lake Michigan.”
The new results indicate the liquid is mostly methane, somewhat similar to a liquid form of natural gas on Earth.
An innovative solar observatory is adding a key piece to the puzzle of the enigma that is our Sun.
Its two of key questions in heliophysics: why does our Sun have a corona? And why is the temperature of the corona actually higher than the surface of the Sun?
This week, researchers released results from the preliminary first six months of data from NASA’s Interface Region Imaging Spectrograph, known as IRIS. The findings were presented at the Fall American Geophysical Union Meeting this past Monday.
IRIS was launched on June 27th of this year on a Pegasus-XL rocket deployed from the belly of a Lockheed L-1011 aircraft flying out of Vandenberg Air Force Base. IRIS can focus in on a very specific interface region of the Sun sandwiched between the dazzling solar photosphere and the transition to the corona. To accomplish this, IRIS employs an ultraviolet slit spectrograph looking at ionized gas spectra.
IRIS in the clean room. The spacecraft is only about 2 metres in length, about the height of a person. (Credit: Lockheed Martin).
“The quality of images and spectra we are receiving is amazing,” IRIS Principal Investigator Alan Title said in a recent press release from the NASA Goddard Space Flight Center. While other missions may take over a decade to go from the drawing board to the launch pad, IRIS was developed and deployed into Low Earth Orbit in just 44 months.
IRIS offers scientists a new tool to probe the Sun and a complimentary instrument to platforms such as Hinode, the Solar Heliospheric Observatory (SOHO) and NASA’s Solar Dynamics Observatory. In fact, IRIS has a better resolution than SDO’s AIA imagers or Hinode when it comes to this key solar interface region. IRIS has a 20x greater resolution in time, and 25x the spatial resolution of any former space-based UV spectrometer deployed.
“We are seeing rich and unprecedented images of violent events in which gases are accelerated to very high velocities while being rapidly heated to hundreds of thousands of degrees,” said Lockheed Martin science lead on the IRIS mission Bart De Pontieu. These observations are key to backing up theoretical models of solar dynamics as well as testing and formulating new ones of how our Sun works.
IRIS bridges this crucial gap between the photosphere and the lower chromosphere of the Sun. While the solar surface roils at relatively placid 6,000 degrees Celsius, temperatures rise into the range of 2-3 million degrees Celsius as you move up through the transition region and into the corona.
Two key solar phenomena that are of concern to solar researchers can be examined by IRIS in detail. One is the formation of prominences, which show up as long looping swirls of solar material rising up from the surface of the Sun. Prominences can be seen from backyard telescopes at hydrogen alpha wavelengths. IRIS can catch and track their early modeling with unprecedented resolution. Images released from IRIS show the fine structure of targeted prominences as they evolve and rise off the surface of the Sun. When a prominence and accompanying coronal mass ejection is launched in our direction, disruption of our local space environment caused by massive solar storm can result.
Slit jaw spectra images (the two strips to the left) and imaging of spicules (to the right) as seen by IRIS. (Credit: NASA/IRIS).
The second phenomenon targeted by IRIS is the formation of spicules, which are giant columns of gas rising from the photosphere. Although the spicules look like hair-fine structures through Earth-based solar telescopes, they can be several hundred kilometres wide and as long as the Earth. Short-lived, spicules race up from the surface of the Sun at up to 240,000 kilometres per hour and seem to play a key role in energy and heat transfer from the solar surface up through the atmosphere. IRIS is giving us a view of the evolution of spicules for the first time, and they’re proving to be even more complex than theory previously suggested.
“We see discrepancies between these observations and the models, and that is great news for advancing knowledge. By seeing something we don’t understand, we have a chance of learning something new,” Said University of Oslo astrophysicist Mats Carlsson.
Like SDO and SOHO, data and images from IRIS are free for the public to access online. Though the field of view for IRIS is a narrow 2’ to 4’ arc minutes on a side – the solar disk spans about 30’ as seen from the Earth – IRIS gives us a refined view of “where the action is.”
Where is IRIS looking? This snapshot gives some context of the IRIS field of view (green and red boxes) and black and white insets versus SDO’s AIA full disk view of the Sun. (Credit: NASA/SDO/IRIS).
And this all comes at an interesting time, as our nearest star crosses the sputtering solar maximum for Cycle #24.
The equivalent of 50 million CPU hours were utilized in constructing and modeling what IRIS sees. The reconstruction was an international effort, spanning the Partnership for Advanced Computing in Europe, the Norwegian supercomputing collaboration, and NASA’s Ames Research Center.
IRIS also faced the additional challenge of weathering a 2.5 week period of inactivity due to the U.S. government shutdown this fall. Potential impacts due to sequestration remain an issue, though small explorer missions such as IRIS demonstrate how we can do more with less.
“We’ve made a giant step forward in characterizing the heat transfer properties of this region between the visible surface and the corona, which is key to understanding how the outer atmosphere of the Sun exists, and is key to understanding the outer atmosphere that the Earth lies in,” said Alan Title, referring to the tenuous heliosphere of the Sun extending out through the solar system.
Understanding the inner working of our Sun is vital: no other astronomical body has as big an impact on life here on Earth.
IRIS is slated for a two-year mission, though as is the case with most space-based platforms, researchers will work to get every bit of usefulness out of the spacecraft that they can. And it’s already returning some first-rate science at a relatively low production cost. This is all knowledge that will help us as a civilization live with and understand our often tempestuous star.
UV observations from Hubble show the size of water vapor plumes coming from Europa's south pole (NASA, ESA, and M. Kornmesser)
It’s been known since 2005 that Saturn’s 300-mile-wide moon Enceladus has geysers spewing ice and dust out into orbit from deep troughs that rake across its south pole. Now, thanks to the Hubble Space Telescope (after 23 years still going strong) we know of another moon with similar jets: Europa, the ever-enigmatic ice-shelled moon of Jupiter. This makes two places in our Solar System where subsurface oceans could be getting sprayed directly into space — and within easy reach of any passing spacecraft.
(Psst, NASA… hint hint.)
The findings were announced today during the meeting of the American Geophysical Union in San Francisco.
“The discovery that water vapor is ejected near the south pole strengthens Europa’s position as the top candidate for potential habitability,” said lead author Lorenz Roth of the Southwest Research Institute (SwRI) in San Antonio, Texas. “However, we do not know yet if these plumes are connected to subsurface liquid water or not.”
The 125-mile (200-km) -high plumes were discovered with Hubble observations made in December 2012. Hubble’s Space Telescope Imaging Spectrograph (STIS) detected faint ultraviolet light from an aurora at the Europa’s south pole. Europa’s aurora is created as it plows through Jupiter’s intense magnetic field, which causes particles to reach such high speeds that they can split the water molecules in the plume when they hit them. The resulting oxygen and hydrogen ions revealed themselves to Hubble with their specific colors.
Unlike the jets on Enceladus, which contain ice and dust particles, only water has so far been identified in Europa’s plumes. (Source)
Rendering showing the location and size of water vapor plumes coming from Europa’s south pole.
The team suspects that the source of the water is Europa’s long-hypothesized subsurface ocean, which could contain even more water than is found across the entire surface of our planet.
“If those plumes are connected with the subsurface water ocean we are confident exists under Europa’s crust, then this means that future investigations can directly investigate the chemical makeup of Europa’s potentially habitable environment without drilling through layers of ice,” Roth said. “And that is tremendously exciting.”
One other possible source of the water vapor could be surface ice, heated through friction.
Cassini image of ice geysers on Enceladus (NASA/JPL/SSI)
In addition the Hubble team found that the intensity of Europa’s plumes, like those of Enceladus, varies with the moon’s orbital position around Jupiter. Active jets have been seen only when Europa is farthest from Jupiter. But the researchers could not detect any sign of venting when Europa is closer.
One explanation for the variability is Europa undergoes more tidal flexing as gravitational forces push and pull on the moon, opening vents at larger distances from Jupiter. The vents get narrowed or even seal off entirely when the moon is closest to Jupiter.
Still, the observation of these plumes — as well as their varying intensity — only serves to further support the existence of Europa’s ocean.
“The apparent plume variability supports a key prediction that Europa should tidally flex by a significant amount if it has a subsurface ocean,” said Kurt Retherford, also of SwRI.
(Science buzzkill alert: although exciting, further observations will be needed to confirm these findings. “This is a 4 sigma detection, so a small uncertainly that the signal is just noise in the instruments,” noted Roth.)
“If confirmed, this new observation once again shows the power of the Hubble Space Telescope to explore and opens a new chapter in our search for potentially habitable environments in our solar system.”
– John Grunsfeld, NASA’s Associate Administrator for Science
So. Who’s up for a mission to Europa now?(And unfortunately in this case, Juno doesn’t count.)
“Juno is a spinning spacecraft that will fly close to Jupiter, and won’t be studying Europa,” Kurt Retherford told Universe Today. “The team is looking hard how we can optimize, maybe looking for gases coming off Europa and look at how the plasma interacts with environment, so we really need a dedicated Europa mission.”
We couldn’t agree more.
The findings were published in the Dec. 12 online issue of Science Express.
Image credits: Graphic Credit: NASA, ESA, and L. Roth (Southwest Research Institute and University of Cologne, Germany) Science Credit: NASA, ESA, L. Roth (Southwest Research Institute and University of Cologne, Germany), J. Saur (University of Cologne, Germany), K. Retherford (Southwest Research Institute), D. Strobel and P. Feldman (Johns Hopkins University), M. McGrath (Marshall Space Flight Center), and F. Nimmo (University of California, Santa Cruz)
A view of the International Space Station as seen by the last departing space shuttle crew, STS-135. Credit: NASA
The decision to launch a cargo flight to the International Space Station next week has been pushed back until Monday (Dec. 16) because of a cooling problem on station that forced the shutdown of redundant systems, according to a NASA update.
Orbital Sciences’ Cygnus commercial spacecraft is expected to blast off on Dec. 18 from the Wallops Flight Facility in Virginia. However, with some station systems offline, the launch does not now meet certain “commit criteria” to make its journey to space next week, said Kenny Todd, the space station’s mission integration and operations manager.
“We haven’t lost any primary functionality,” he said in a NASA Television update today (Dec. 12), emphasizing that the six-person Expedition 38 crew is fine. “There is some redundancy that we’re down right now, but that’s not something I would call critical to day-to-day station operations.”
While a spacewalk is a possibility to fix the problem, it’s too early to say what NASA and other space station partners will decide to do.
NASA controllers spent the night examining a control valve blamed for causing an ammonia pump to shut down yesterday (Dec. 12). The space station uses liquid ammonia to maintain its temperature, pumping the ammonia through external radiators to bleed off heat. Astronauts have made periodic spacewalks to repair parts of the ammonia system, most recently in May when Expedition 35 replaced a pump controller box on the P6 (far port) truss just days before some crew members went home.
Expedition 35 Flight Engineers Chris Cassidy (left) and Tom Marshburn on a spacewalk on May 11 to inspect and replace a pump controller box on the International Space Station’s far port truss (P6) leaking ammonia coolant. Credit: NASA.
“The pump module on one of ISS two external cooling loops automatically shut down today when it got too cold,” stated the NASA Johnson Space Center Twitter feed yesterday (Dec. 11).
“The pump was brought back online, but they think a valve may not be working correctly inside it. Some of the station’s internal electrical systems were moved over to the second loop, and some noncritical things were powered down. The crew was always safe and will work with the ground teams as they figure out what caused the issue.”
Non-critical systems were powered down in the Harmony node, Columbus Laboratory and Japanese Kibo laboratory. After confirming that the new configuration was stable, controllers began this morning (EST) to move the troublesome valve to several positions and monitor the effect on cooling temperatures, according to a NASA TV update.
The Japanese Kibo module on the International Space Station as photographed by a member of the Expedition 38 crew in 2013. Credit: NASA
The crew is going about their activities as much as possible, although they’re on a “reduced timeline” because some of the experiments aren’t running as usual. (Science collected up to now is “not at risk”, Todd said.)
Responding to questions on social media, NASA astronaut Douglas Wheelock — who led three unplanned spacewalks in 2010 to replace a broken ammonia pump module on the S1 truss in the same cooling loop — said he is working with Mission Control to see what needs to be done next.
NASA astronaut Douglas Wheelock during a contingency spacewalk Nov. 16, 2010 after an ammonia cooling pump failed aboard the International Space Station. During this spacewalk, Wheelock and fellow Expedition 24 crew member Tracy Caldwell installed a spare ammonia pump module on the S1 Truss on the space station. The duo did three contingency spacewalks during the mission to address the problem. Credit: NASA
Astronauts have been troubleshooting the suit periodically on board station, but NASA is planning to send it back on the next SpaceX Dragon flight to Earth for further investigation. SpaceX isn’t planning to get to the station again until late February, media reports say. Russian spacewalks can still continue as they use a separate suit; the most recent one took place in November with the Olympic torch.
While Todd didn’t quite say the ban on spacewalks has been lifted, he added that NASA has new procedures in place to guard against another crew member facing the same water issue. He did not elaborate on what those procedures are.
The current launch window for Cygnus extends as far as Dec. 21 and “possibly” the 22nd, Todd said, but emphasized more time is needed to come to a decision. “At this point, for lack of a better term, we’re going to kick the can a little bit and let the team work a little bit more,” he said.
Updates will follow as the situation and fix progresses.
The Universe is expanding. Distant galaxies are moving away from us in all directions. It’s natural to wonder, is everything expanding? Is the Milky Way expanding? What about the Solar System, or even objects here on Earth. Are atoms expanding?
Nope. The only thing expanding is space itself. Imagine the Universe as loaf of raisin bread rising in the oven. As the bread bakes, it’s stretching in all directions – that’s space. But the raisins aren’t growing, they’re just getting carried away from each other as there’s more bread expanding between them.
Space is expanding from the Big Bang and the acceleration of dark energy. But the objects embedded in space, like planets, stars, and galaxies stay exactly the same size. As space expands, it carries galaxies away from each other. From our perspective, we see galaxies moving away in every direction. The further galaxies are, the faster they’re moving.
There are a few exceptions. The Andromeda Galaxy is actually moving towards the Milky Way, and will collide with us in about 4 billion years.In this case, the pull of gravity between the Milky Way and Andromeda is so strong that it overcomes the expansion of the Universe on a local level.
Within the Milky Way, gravity holds the stars together, and same with the Solar System. The nuclear force holding atoms together is stronger than this expansion at a local scale. Is this the way it will always be? Maybe. Maybe not.
A few decades ago, astronomers thought that the Universe was expanding because of momentum left over from the Big Bang. But with the discovery of dark energy in 1998, astronomers realized there was a new possibility for the future of the Universe. Perhaps this accelerating dark energy might be increasing over time.
In billions years from now, the expansive force might overcome the gravity that holds galaxies together. Eventually it would become so strong that star systems, planets and eventually matter itself could get torn apart.This is a future for the Universe known as the Big Rip. And if it’s true, then the space between stars, planets and even atoms will expand in the far future.
The space between the galaxies is expanding. Credit: NASA/HST
Is this going to happen? Astronomers don’t know. Their best observations so far can’t rule it out, or confirm it. And so, future observations and space missions will try to calculate the rate of dark energy’s expansion.
So no, matter on a local level isn’t expanding. The spaces between planets and stars isn’t growing. Only the distances between galaxies which aren’t gravitationally bound to each other is increasing. Because space itself is expanding.
Layered deposits in Juventae Chasma as seen by the European Space Agency's Mars Express orbiter's high-resolution stereo camera in November 2013. Credit: ESA/DLR/FU Berlin (G. Neukum)
Above is a time capsule of more than three billion years of Mars history. The right-hand side shows a bunch of blocky-looking things that formed after volcanic activity made the walls of Juventae Chasma collapse. In the center are what the European Space Agency calls “mystery mounds” made up of sulphate materials (indicating that they were changed by water a long time ago.)
“The mounds contain numerous layers that were most likely built up as lake-deposits during the Chasma’s wet epoch. But ice-laden dust raining out from the atmosphere – a phenomenon observed at the poles of Mars – may also have contributed to the formation of the layers,” ESA stated.
“While the water has long gone, wind erosion prevails, etching grooves into the exposed surfaces of the mounds and whipping up the surrounding dust into ripples.”
The picture was snapped Nov. 4 by the European Space Agency’s Mars Express mission. There’s been a lot of talk about water on Mars this past week, between this possible salty water find at the equator and news of the Mars Curiosity rover stumbling on to an ancient lake that could have supported life.
Mars Express has been humming along for 10 years and counting above the Red Planet. Check out some of its top discoveries in the past decade in this past article by Universe Today’s Ken Kremer.
This artist’s concept shows Mars Express set against a 35 km-wide crater in the Vastitas Borealis region of Mars at approximately 70.5°N / 103°E. The crater contains a permanent patch of water-ice that likely sits upon a dune field – some of the dunes are exposed towards the top left in this image. Copyright ESA/DLR/FU-Berlin-G.Neukum
