A Coronal Mass Ejection (CME) from the Sun frames Mercury, as observed by the SOlar Heliospheric Observatory (SOHO) on 13 August 2014.
The shaded blue disc surrounding the Sun at the center is a mask in SOHO’s LASCO instrument that blots out direct sunlight to allow study of the details in the Sun’s corona.
This animated blink comparison shows five different versions of observations that NASA's Curiosity made about one hour apart while Mercury was passing in front of the Sun on June 3, 2014. Two sunspots, each about the diameter of Earth, also appear in the images, moving much less during the hour than Mercury's movement.
This is the first observation of any planet's transit of the Sun observed from any planet other than Earth. It is also the first observation of Mercury from Mars.
With precise information about when the transit would occur, the rover team planned this observation using the telephoto-lens (right-eye) camera of Curiosity's Mast Camera (Mastcam) instrument. The camera has solar filters for routine observations of the Sun used for assessing the dustiness of the atmosphere. Mercury appears as a faint darkening that moves across the face of the Sun. It is about one-sixth the size of a right-Mastcam pixel at the interplanetary distance from which these images were taken, so it does it does not appear as a distinct shape, but its position follows Mercury's known path.
Each of the five versions of the image presented here blinks back and forth between two views recorded at different times during the transit. North is up. The version on the left is minimally enhanced, for a natural looking image of the Sun with two sunspots barely visible. The second version has limb darkening removed, the edges masked. The third has enhanced contrast. The fourth has a line added to indicate the calculated path of Mercury during the transit. The fifth adds annotation to point out which spot is Mercury (in the cross hairs) and to identify two sunspots.
For a video presentation of these images, see http://www.jpl.nasa.gov/video/?id=1309.
Transits of the Sun by Mercury and Venus, as seen from Earth, have significant history. Observations of Venus transits were used to measure the size of the solar system, and Mercury transits were used to measure the size of the Sun.
The pair of bright star-like features in the upper panel are not stars at all, but the Earth and Moon! MESSENGER was at a distance of 98 million kilometers (61 million miles) from Earth when this picture was taken. The computer-generated image in the lower left shows how the Earth appeared from Mercury at the time. Much of the Americas, all of Europe and Africa, the Middle East, and much of Asia were visible.
MESSENGER took this image as part of a campaign to search for natural satellites of Mercury. Mercury has no moons that we know of. If any exist, they must be small (less than a few kilometers), or we would have seen them by now. The strategy for the satellite search involves taking multiple images of locations at predetermined distances from Mercury, from 2.5 to 25 times the planet radius. Pictures of these points in space are captured at intervals ranging from seconds to nearly an hour, depending on their distances from Mercury. A moving satellite will appear at different positions in images of the same region of space taken at different times.
The Earth and Moon appear very large in this picture because they are overexposed. When looking for potentially dim satellites, long exposures are required to capture as much light as possible. Consequently, bright objects in the field of view become saturated and appear artificially large. In fact, the Earth and Moon are each less than a pixel in size, and no details on either can be seen. The "tails" pointing downward from the Earth and Moon are artifacts caused by the image saturation. These can be seen clearly in the zoomed image in the center lower panel.
This image was taken on the same day that images with Earth in the scene were acquired by the Cassini spacecraft, as part of a mosaic of the backlit Saturn system (http://saturn.jpl.nasa.gov/news/waveatsaturn).
One day later in the search for satellites of Mercury, MESSENGER again took similar images of the Earth and Moon. The date of those images, July 20, was the 44th anniversary of the Apollo 11 landing on the Moon. All six Apollo landing sites are illuminated in the MESSENGER images, although they cannot be resolved. Their locations are marked on the simulated image in the lower right panel.
The background for this image is the region between the constellations Sagittarius (the archer) and Scutum (the shield). The right ascension and declination of Earth are 18h 55m 44s and -18° 25' 31", respectively. Pluto is also in the field of view but far too dim to be seen.
Date Acquired: July 19, 2013, 11:54:41 UTC
Image Mission Elapsed Time (MET): 1016558881
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC Filter: 2 (clear filter)
Field of View: The WAC has a 10.5° field of view
This video showcases a small sampling of the thousands of images taken by the spacecraft, as well as animations illustrating how MESSENGER moves in orbit and how its orbit has changed during the mission.
The opening sequence is from the approach images from the first flyby in 2008. The first animation to follow (at 0:15) shows MESSENGER in its primary mission 12-hour orbit. The relevance of the November 9, 2011, date is that this was when the MESSENGER team was advised that NASA had approved the proposal for an extended mission, allowing the mission to continue making new observations from March 2012 to March 2013. The animation at 0:22 gives you an idea of the movement and gyrations ("dancing") that the spacecraft undergoes while it performs a schedule packed full of observations that take place over one Earth day. The animation sequence at 0:59 gives you a "top down" view over Mercury's north pole from when MESSENGER first went into orbit until several months into the extended mission. The apparent size of the orbit shrinks from the start of the animation to the end, as shortly into the extended mission, MESSENGER's orbital period was shrunk from 12-hours to 8-hours. The animation sequence at 1:44 shows MESSENGER's "dance" on the first day of the extended mission. The other images and embedded movies can be found in the Gallery section of the MESSENGER website.
Some highlight images of note include:
At 0:48 - Blue rays of Bek crater
At 0:54 - Basho crater
At 0:57 - Poe crater in Caloris basin
At 1:17 - MASCS instrument surface scans in ultraviolet and infrared
At 1:19 - A perspective view of the northern polar region, color-coded to MLA topography
At 1:27 - Rembrandt impact basin
At 1:29 - Rembrandt impact basin superimposed on the US for size comparison
At 1:34 - Rachmaninoff impact basin, 3D effect crated using the digital elevation model
At 1:34 - Debussy crater
At 1:58 - Beagle rupes
At 2:04 - Mosaic view of north pole, showing the shadowed regions
At 2:06 - As previous, with superimposed radar data indicating likely water-ice deposits
At 2:11 - A volcanic vent near the edge of Caloris basin
At 2:34 - Derain crater
At 2:36 - Disney crater and two unnamed craters that resemble Mickey Mouse
At 2:38 - Basho crater while the Sun is low in the sky
At 2:40 - Basho crater again, but now with the Sun nearly overhead
At 2:45 - Degas crater
At 2:58 - 'Weird terrain' at the Caloris antipode
At 3:03 - Waters crater with the 'blue tongue' of dark impact melt material
At 3:10 - Seuss crater
At 3:13 - Caloris basin
At 3:15 - Pit in Scarlatti crater, with prominent hollows on the pit rim
At 3:17 - Enhanced color of Caloris basin
At 3:22 - A lava channel that had flowed into the Kofi crater
At 3:29 - More detail of Caloris basin floor
At 3:30 - The young, bright-rayed Mena crater
At 3:37 - Central peaks of Eminescu crater, with hollows around the bases of the peaks
At 3:39 - Apollodorus and Pantheon fossae
At 3:41 - The hollows on the floor of Sander crater
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. Visit the Why Mercury? section of this website to learn more about the key science questions that the MESSENGER mission is addressing. During the one-year primary mission, MDIS acquired 88,746 images and extensive other data sets. MESSENGER is now in a year-long extended mission, during which plans call for the acquisition of more than 80,000 additional images to support MESSENGER's science goals.
NASA's STEREO-B spacecraft photographed "wild striations" in the tail of Comet Pan-STARRS as it passed by the sun.
The figure above shows an oblique view of a 280 km long scarp. The color scale on this figure represents elevation in which red is high and blue is low. This scarp is interpreted to be a surface-breaking thrust fault. Thrust faults are surface manifestations of the shrinkage of the planet resulting from the cooling of its interior. Notice that the terrain on the left side of the scarp stands about 2 km higher than that of the right side of the scarp. To give you a sense of the scale of this scarp, the state of Delaware has been superposed on the figure.
Center Latitude: 58.18°
Center Longitude: 307.69° E
Scale: The crater that is being cross-cut by this scarp is about 108 km (67 mi.) in diameter.
NASA's Kepler mission has discovered a new planetary system that is home to the smallest planet yet found around a star like our sun, approximately 210 light-years away in the constellation Lyra.
The line up compares artist's concepts of the planets in the Kepler-37 system to the moon and planets in the solar system. The smallest planet, Kepler-37b, is slightly larger than our moon, measuring about one-third the size of Earth. Kepler-37c, the second planet, is slightly smaller than Venus, measuring almost three-quarters the size of Earth. Kepler-37d, the third planet, is twice the size of Earth.
A "year" on these planets is very short. Kepler-37b orbits its host star every 13 days at less than one-third the distance Mercury is to the sun. The other two planets, Kepler-37c and Kepler-37d, orbit their star every 21 and 40 days. All three planets have orbits lying less than the distance Mercury is to the sun, suggesting that they are very hot, inhospitable worlds.
A global color map of Mercury's surface has been created by mosaicking thousands of sets of images obtained by the MESSENGER Wide Angle Camera (WAC). The colors shown here are related to variations in the spectral reflectance across the planet. This view captures both compositional differences and differences in how long materials have been exposed at Mercury's surface. Young crater rays, arrayed radially around fresh impact craters, appear light blue or white. Medium- and dark-blue areas are a geologic unit of Mercury's crust known as the "low-reflectance material," thought to be rich in a dark, opaque mineral. Tan areas are plains formed by eruption of highly fluid lavas. The large circular area near the top center is the Caloris impact basin, whose interior is filled with smooth, somewhat younger volcanic plains. Small orangish spots are materials deposited by explosive volcanic eruptions.
The color base map shown here consists of MDIS images taken through eight different color filters. It is part of a global color map that covers more than 99% of Mercury's surface with an average resolution of about 1 kilometer per pixel.
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS). This is an enhanced-color presentation created from a statistical combination of images taken through eight of the WAC filters.
Though Mercury is not known for having an especially colorful surface, some regions show a strong local contrast in color. Like other craters in Caloris, the interior and ejecta of Atget are darker and bluer than the typical brown volcanic plains. These craters help scientists to get a look at the three-dimensional compositional variations with the Caloris basin, and provide a way to judge the thickness of the volcanic plains (over 2 km here!). North is up in this image.
Date acquired: December 09, 2012
Image Mission Elapsed Time (MET): 263555174, 263555178, 263555194
Image ID: 3108404, 3108405, 3108409
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filters: 9, 7, and 6 (996, 748, and 433 nanometers) in red, green, and blue
Center Latitude: 25.92°
Center Longitude: 166.2° E
Resolution: 224 meters/pixel
Scale: Atget is 100 km (62 mi.) in diameter
Incidence Angle: 25.9°
Emission Angle: 52.6°
Phase Angle: 78.5°
In the lower left portion of today's image is a small, young, rayed impact crater. The rays have a typical bluish cast in this color presentation. The relatively blue color in this case is caused partly by the extreme youth of the rays (surfaces exposed to the space environment of Mercury for long periods tend to "redden" and darken). In addition, the crater formed in a dark, bluish terrain called the "Low Reflectance Material." The tan area toward the top of the image is "intermediate terrain."
Date acquired: November 30, 2011
Image Mission Elapsed Time (MET): 231181189, 231181209, 231181193
Image ID: 1078917, 1078922, 1078918
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filters: 9, 7, 6 (996, 748, 433 nanometers) in red, green, and blue.
Center Latitude: -34.19°
Center Longitude: 133.6° E
Resolution: 647 meters/pixel
Scale: The small rayed crater is about 16 km (10 mi.) in diameter.
Incidence Angle: 54.9°
Emission Angle: 3.9°
Phase Angle: 58.7°
The Mercury Laser Altimeter (MLA) ranges at a wavelength of 1064 nm at an 8 Hz rate and illuminates Mercury's surface in spots between 15 and 100 m across, depending on the MESSENGER spacecraft's range. The MLA has so far returned 10.7 million precise measurements of the elevation of Mercury's northern hemisphere. Shown here is a polar stereographic projection of the topography of Mercury from the north pole to 5° S. The outlines of selected major impact structures are shown as black circles.
Topographic information from the Mercury Laser Altimeter (MLA) is used to colorize a image mosaic of Goethe basin, located in Mercury's northern region. The purple colors are low and white is the highest; the total range of heights shown in this view is about 1 kilometer. Goethe basin is home to a variety of interesting features, including ghost craters with graben, wrinkle ridges that outline the basin, and dark craters that host radar-bright materials.
Scale: The width of this image is about 250 kilometers (150 miles)
This elevation map of the Beethoven basin is color-coded to show the height of features on Mercury's surface. Mercury lacks a "sea level," so the zero-point reference elevation is defined to be the mean planetary radius of 2440 km. Blue areas, such as within Bello crater on the floor of Beethoven, have negative elevations. The red and white areas to the southwest are more than 8 km higher than the lowest points in this area.
Center Latitude: -20°
Center Longitude: 236° E
Scale: Beethoven basin is ~650 km (404 miles) in diameter
Image information: A digital terrain model (DTM) derived from Mercury Dual Imaging System (MDIS) stereo images. The lateral spacing is 330 meters and the map is in stereographic (conformal) projection. The image is taken from abstract number 1913 submitted to the 2012 Lunar and Planetary Science Conference, by Frank Preusker and colleagues.
This high-resolution enhanced color view of Kuiper crater shows not just the bright rays that extend out from this relatively young crater but also the redder color of Kuiper's ejecta blanket. The redder color may be due to a compositionally distinct material excavated from depth by the impact that formed Kuiper.
Date acquired: September 02, 2011
Image Mission Elapsed Time (MET): 223443634, 223443638, 223443654
Image ID: 708128, 708129, 708133
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 9 (1000 nanometers), 7 (750 nanometers), 6 (433 nanometers) as red-green-blue
Center Latitude: -11.97°
Center Longitude: 328.4° E
Resolution: 380 meters/pixel
Scale: Kuiper has a diameter of 62 kilometers (39 miles)
Incidence Angle: 33.4°
Emission Angle: 21.4°
Phase Angle: 54.8°
In March 2011, MESSENGER became the first spacecraft to orbit the planet Mercury. In July of the same year, the Dawn spacecraft became the first to orbit a main-belt asteroid, Vesta. Both MESSENGER and Dawn are missions in the Discovery program, NASA's lowest-cost category of planetary mission.
The image above shows Mercury on the left, and Vesta on the right. Both surfaces are marked by impact craters, but the most immediately noticeable difference is that Vesta has a much more irregular shape. This is a consequence of Mercury's far larger gravity, which has squeezed the planet into a sphere. Vesta's weak gravity is less able to overcome the strength of the rocks. Mercury's mass is about 1300 times greater than that of Vesta.
MESSENGER image of planet Mercury (left)
Date acquired: September 29, 2009
Image Mission Elapsed Time (MET): 162741055
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 7 (748 nanometers)
Scale: Mercury's diameter is 4880 km (3030 mi.)
Dawn image of asteroid Vesta (right)
Date acquired: July 18, 2011
Instrument: Dawn Framing Camera, clear filter
Scale: Vesta's diameter is about 530 km (329 mi.)
Forty light years from Earth, a rocky world named "55 Cancri e" circles perilously close to a stellar inferno. Completing one orbit in only 18 hours, the alien planet is 26 times closer to its parent star than Mercury is to the Sun. If Earth were in the same position, the soil beneath our feet would heat up to about 3200 F. Researchers have long thought that 55 Cancri e must be a wasteland of parched rock.
Now they’re thinking again. New observations by NASA's Spitzer Space Telescope suggest that 55 Cancri e may be wetter and weirder than anyone imagined.
Spitzer recently measured the extraordinarily small amount of light 55 Cancri e blocks when it crosses in front of its star. These transits occur every 18 hours, giving researchers repeated opportunities to gather the data they need to estimate the width, volume and density of the planet.
According to the new observations, 55 Cancri e has a mass 7.8 times and a radius just over twice that of Earth. Those properties place 55 Cancri e in the "super-Earth" class of exoplanets, a few dozen of which have been found. Only a handful of known super-Earths, however, cross the face of their stars as viewed from our vantage point in the cosmos, so 55 Cancri e is better understood than most.
When 55 Cancri e was discovered in 2004, initial estimates of its size and mass were consistent with a dense planet of solid rock. Spitzer data suggest otherwise: About a fifth of the planet's mass must be made of light elements and compounds--including water. Given the intense heat and high pressure these materials likely experience, researchers think the compounds likely exist in a "supercritical" fluid state.
A supercritical fluid is a high-pressure, high-temperature state of matter best described as a liquid-like gas, and a marvelous solvent. Water becomes supercritical in some steam turbines--and it tends to dissolve the tips of the turbine blades. Supercritical carbon dioxide is used to remove caffeine from coffee beans, and sometimes to dry-clean clothes. Liquid-fueled rocket propellant is also supercritical when it emerges from the tail of a spaceship.
On 55 Cancri e, this stuff may be literally oozing--or is it steaming?--out of the rocks.
With supercritical solvents rising from the planet’s surface, a star of terrifying proportions filling much of the daytime sky, and whole years rushing past in a matter of hours, 55 Cancri e teaches a valuable lesson: Just because a planet is similar in size to Earth does not mean the planet is like Earth.
It’s something to re-think about.
The young rays of Mena crater contrast brightly against the surrounding surface, though the rays will gradually fade with time. The asymmetric pattern of the rays, with a gap in the south-western direction, may be due to the angle at which the impact that formed the crater occurred, or to the fact that Mena formed on the rim of a larger pre-existing impact crater, as seen in this image.
Date acquired: November 12, 2011
Image Mission Elapsed Time (MET): 229581348, 229581352, 229581356
Image ID: 1003074-1003076
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filters: 9, 7, 6 (1000, 750, 430 nanometers) as red, green, blue
Center Latitude: -0.97°
Center Longitude: 234.0° E
Resolution: 257 meters/pixel
Scale: Mena has a diameter of 15 km (9 miles)
Incidence Angle: 29.7°
Emission Angle: 16.3°
Phase Angle: 46.0°
NASA's MESSENGER spacecraft has discovered strange hollows on the surface of Mercury. Images taken from orbit reveal thousands of peculiar depressions at a variety of longitudes and latitudes, ranging in size from 60 feet to over a mile across and 60 to 120 feet deep. No one knows how they got there.
"These hollows were a major surprise," says David Blewett, science team member from the Johns Hopkins University Applied Physics Laboratory. "We've been thinking of Mercury as a relic – a place that's really not changing much anymore, except by impact cratering. But the hollows appear to be younger than the craters in which they are found, and that means Mercury's surface is still evolving in a surprising way."
Mars Reconnaissance Orbiter spotted similar depressions in the carbon dioxide ice at Mars' south pole, giving that surface a "swiss cheese" appearance. But on Mercury they're found in rock and often have bright interiors and halos.
"We've never seen anything quite like this on a rocky surface."
If you could stand in one of these "sleepy" hollows on Mercury's surface, you'd find yourself, like Ichabod Crane, in a quiet, still, haunting place, with a black sky above your head.
"There's essentially no atmosphere on Mercury," explains Blewett. "And with no atmosphere, wind doesn't blow and rain doesn't fall. So the hollows weren't carved by wind or water. Other forces must be at work."
As the planet closest to the Sun, Mercury is exposed to fierce heat and extreme space weather. Blewett believes these factors play a role.
A key clue, he says, is that many of the hollows are associated with central mounds or mountains inside Mercury's impact craters. These so-called “peak rings” are thought to be made of material forced up from the depths by the impact that formed the crater. Excavated material could be unstable when it finds itself suddenly exposed at Mercury's surface.
"Certain minerals, for example those that contain sulfur and other volatiles, would be easily vaporized by the onslaught of heat, solar wind, and micrometeoroids that Mercury experiences on a daily basis," he says. "Perhaps sulfur is vaporizing, leaving just the other minerals, and therefore weakening the rock and making it spongier. Then the rock would crumble and erode more readily, forming these depressions."
MESSENGER has indeed proven Mercury unexpectedly rich in sulfur. That in itself is a surprise that's forcing scientists to rethink how Mercury was formed. The prevailing models suggest that either (1) very early in Solar System history, during the final sweep-up of the large planetesimals that formed the planets, a colossal impact tore off much of Mercury's rocky outer layering; or (2) a hot phase of the early Sun heated up the surface enough to scorch off the outer layers. In either case, the elements with a low boiling point – volatiles like sulfur and potassium – would have been driven off.
But they're still there.
"The old models just don't fit with the new data, so we'll have to look at other hypotheses."
To figure out how the planets and Solar System came to be, scientists must understand Mercury.
"It's the anchor at one end of the Solar System. Learning how Mercury formed will have major implications for the rest of the planets. And MESSENGER is showing that, up to now, we've been completely wrong about this little world in so many ways!"
What other surprises does Mercury hold? The sleepy hollows of the innermost planet may be just the beginning.
After its first Mercury solar day (176 Earth days) in orbit, MESSENGER has nearly completed two of its main global imaging campaigns: a monochrome map at 250 m/pixel and an eight-color, 1-km/pixel color map. Apart from small gaps, which will be filled in during the next solar day, these global maps now provide uniform lighting conditions ideal for assessing the form of Mercury's surface features as well as the color and compositional variations across the planet. The orthographic views seen here, centered at 75° E longitude, are each mosaics of thousands of individual images. At right, images taken through the wide-angle camera filters at 1000, 750, and 430 nm wavelength are displayed in red, green, and blue, respectively.
The large Rembrandt basin is evident on the left side of this image, and, in contrast to the relatively darker material surrounding Rembrandt, Amaral crater and its bright rays can be seen on the right. Rembrandt basin is an area of particular scientific interest due to its large size, young age, and extensional and contractional characteristics. In fact, Rembrandt was highlighted in a publication of Science magazine in 2009 and featured on the cover.
This image was acquired as part of MDIS's color base map. The color base map is composed of WAC images taken through eight different narrow-band color filters and will cover more than 90% of Mercury's surface with an average resolution of 1 kilometer/pixel (0.6 miles/pixel). The highest-quality color images are obtained for Mercury's surface when both the spacecraft and the Sun are overhead, so these images typically are taken with viewing conditions of low incidence and emission angles.
Date acquired: July 11, 2011
Image Mission Elapsed Time (MET): 218833662, 218833682, 218833666
Image ID: 489008 , 489013, 489009
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 9 (1000 nanometers), 7 (750 nanometers), 6 (433 nanometers) as red-green-blue
Center Latitude: -34.67°
Center Longitude: 100.4° E
Resolution: 1853 meters/pixel
Scale: Rembrandt basin has a diameter of 716 kilometers (445 miles).
Incidence Angle: 50.5°
Emission Angle: 0.4°
Phase Angle: 50.5°
