NASA HiRise: Elysium Planitia region of Mars

This image shows an impact crater that was cut by lava in the Elysium Planitia region of Mars.

The relatively flat, shallow floor, rough surface texture, and possible cooling cracks seem to indicate that the crater was partially filled with lava.

The northern part of the image also shows a more extensive lava flow deposit that surrounds the impact ejecta of the largest impact crater in the image.

Which way did the lava flow? It might appear that the lava flowed from the north through the channel into the partially filled crater.

However, if you look at the anaglyph with your red and blue 3D glasses, it becomes clear that the partially filled crater sits on top of the large crater's ejecta blanket, making it higher than the lava flow to the north. Since lava does not flow uphill, that means the explanation isn't so simple.

We have seen much evidence for lava flows in this region that flowed to much higher levels than the present surface, then deflated or drained away.

That may have happened here: lava flowed from from north to south to fill this crater, but then it drained back to the north, carving this channel.

The topographic information that we gained from having a stereo pair let us answer a question that we could not have with only a single image.

This is a great example of why we take stereo images, where the two images are used to make a 3D image.

NASA MESSENGER: Seuss, a Complex Crater on Mercury

MESSENGER spacecraft in orbit around Mercury spotted Seuss, a complex crater with hollows visible on the crater's floor, at the top left of this image. 

The hollows appear brightly as blue-white features in this image which has had color enhanced.

Just outside of the crater rim, some material appears darker brown, which consists of Low Reflectance Material (LRM).

The impactor that created Seuss probably excavated this material.

Bright crater rays extending from Seuss consist of streams of ejecta thrown from the crater upon impact.

In the bottom right of the image lies an irregular, orange-yellow depression that may be a volcanic vent.

NASA Mars MRO HiRise Image: A Pedestal Crater

Credit: Nasa /JPL /University of Arizona

This HiRISE image shows what is termed a pedestal crater, so-called because the level of the surface adjacent to the crater is elevated relative to the surface of the surrounding terrain.

The raised surface has patterns and a general outline resembling what ejecta would look like after being thrown out from the crater by the impact.

This impact probably occurred at a time when the surface of the whole scene was at the level of the raised surface.

The ejecta landed on the part of this surface close to the crater. Erosion then removed material in the rest of the scene while the impact ejecta shielded the area around the crater, protecting the ground under it from eroding and keeping it high.

The eroded, or “missing”, terrain in the rest of the scene may have contained ice. Lobe shapes at the base of the raised ejecta and polygons (visible when zoomed in) on the surface both suggest the pedestal material may have, or may still, contain ice.

The pattern of ejecta is asymmetric around the crater, suggesting the impactor may have hit the ground traveling from the north-east.

NASA's IRIS: Observing a gigantic CME eruption of solar material

A coronal mass ejection, or CME, surged off the side of the sun on May 9, 2014, and NASA's newest solar observatory caught it in extraordinary detail. 

This was the first CME observed by the Interface Region Imaging Spectrograph (IRIS), which launched in June 2013 to peer into the lowest levels of the sun's atmosphere with better resolution than ever before. 

IRIS must commit to pointing at certain areas of the sun at least a day in advance, so catching a CME in the act involves some educated guesses and a little bit of luck.

"We focus in on active regions to try to see a flare or a CME," said Bart De Pontieu, the IRIS science lead at Lockheed Martin Solar & Astrophysics Laboratory in Palo Alto, California. "And then we wait and hope that we'll catch something. This is the first clear CME for IRIS so the team is very excited."

The IRIS imagery focuses in on material of 30,000 kelvins at the base, or foot points, of the CME.

The line moving across the middle of the movie is the entrance slit for IRIS's spectrograph, an instrument that can split light into its many wavelengths, a technique that ultimately allows scientists to measure temperature, velocity and density of the solar material behind the slit.

The field of view for this imagery is about five Earths wide and about seven-and-a-half Earths tall.


Watch the movie to see how a curtain of solar material erupts outward at speeds of 1.5 million miles per hour.

A coronal mass ejection burst off the side of the sun on May 9, 2014. The giant sheet of solar material erupting was the first CME seen by NASA's Interface Region Imaging Spectrograph (IRIS). 

The field of view seen here is about five Earths wide and about seven-and-a-half Earths tall. Credit: NASA/LMSAL/IRIS/SDO/Goddard

Hubble maps 3-D structure of ejected material around erupting star

Hubble's Wide Field Camera 3 imaged the double-star system T Pyxidis, or T Pyx, over a four-month period. 

T Pyx is a recurrent nova, erupting every 12 to 50 years. 

T Pyx's latest outburst was in April 2011. The star is the white blob in the middle of each image. 

Credit: NASA, ESA, A. Crotts, J. Sokoloski, and H. Uthas (Columbia University), and S. Lawrence (Hofstra University)

A flash of light from a stellar outburst has provided a rare look at the 3-D structure of material ejected by an erupting nova.

Astronomers used NASA's Hubble Space Telescope to observe the light emitted by the close double-star system T Pyxidis, or T Pyx, a recurring nova, during its latest outburst in April 2011.

A nova erupts when a white dwarf, the burned-out core of a sun-like star, has siphoned off enough hydrogen from a companion star to trigger a thermonuclear runaway.

As hydrogen builds up on the surface of the white dwarf, it becomes hotter and denser until it detonates like a colossal hydrogen bomb, leading to a 10,000-fold increase in brightness in a little more than one day.

Nova explosions are extremely powerful, equal to a blast of one million billion tons of dynamite. T Pyx erupts every 12 to 50 years.

Contrary to some predictions, the astronomers were surprised to find the ejecta from earlier outbursts stayed in the vicinity of the star and formed a disk of debris around the nova.

The discovery suggests material continues expanding outward along the system's orbital plane, but it does not escape the system.

Arlin Crotts

"We fully expected this to be a spherical shell," says Arlin Crotts of Columbia University, a member of the research team.

"This observation shows it is a disk, and it is populated with fast-moving ejecta from previous outbursts."

Team member Stephen Lawrence of Hofstra University in Hempstead, N.Y., will present the results Tuesday at the American Astronomical Society meeting in Indianapolis.

Team member Jennifer Sokoloski, also of Columbia University and co-investigator on the project, suggests these data indicate the companion star plays an important role in shaping how material is ejected, presumably along the system's orbital plane, creating the pancake-shaped disk.

The disk is tilted about 30 degrees from face-on toward Earth.

Stephen Lawrence

Using Hubble's Wide Field Camera 3, the team took advantage of the blast of light emitted by the erupting nova to trace the light's path as it lit up the disk and material from previous ejecta.

The disk is so vast, about a light-year across, that the nova's light cannot illuminate all of the material at once.

Instead, the light sweeps across the material, sequentially illuminating parts of the disk, a phenomenon called a light echo.

The light reveals which parts of the disk are nearer to Earth and which sections are farther away. By tracing the light, the team assembled a 3-D map of the structure around the nova.

"We've all seen how light from fireworks shells during the grand finale will light up the smoke and soot from shells earlier in the show," Lawrence said.

"In an analogous way, we're using light from T Pyx's latest outburst and its propagation at the speed of light to dissect its fireworks displays from decades past."

Although astronomers have witnessed light propagating through material surrounding other novae, this is the first time the immediate environment around an erupting star has been studied in three dimensions.

The team's results will appear online June 5 and will be published in the June 20, 2013, issue of the Astrophysical Journal Letters. 

Mars Impact Crater and Ejecta - Image

This enhanced-colour image shows an impact crater and its ejecta and scientists claim it shows some of the best exposures of ancient bedrock on Mars. 

The different colours in this image each represent a different type of rock.