Copland Crater

Visible in the center of this image is the crater Copland, recently named in honor of the American composer and pianist Aaron Copland. Aaron Copland and this crater are both unquestionably worthy candidates for named features on Mercury, but how this specific crater came to be known as Copland has an interesting back-story.

Amateur astronomer Ronald Dantowitz and his colleagues Scott Teare and Marek Kozubal used the Mt. Wilson 60-inch telescope in 1998 to observe a very bright feature on this portion of Mercury's surface, and they assumed that the bright feature was an impact crater. Mr. Dantowitz expressed his wish that the crater be named "Copland" once better images of the area were obtained from spacecraft. Surprisingly, MESSENGER images from Mercury flyby 3 revealed that the small bright feature, seen at the left edge of this image, is not an impact crater but more closely resembles a volcanic vent. No convention for naming volcanic vents on Mercury has yet been adopted, because none were identified prior to MESSENGER's first Mercury flyby. However, even if a convention for naming volcanic features on Mercury is adopted in the future, the naming rules will likely differ from those for impact craters, and thus "Copland" would probably not be an acceptable name for the bright volcanic feature. A MESSENGER team member corresponded with Mr. Dantowitz and suggested that the name Copland be proposed instead for a large crater nearby. He agreed, and the International Astronomical Union (IAU) approved the name Copland on March 3, 2010.

Copland crater is flooded with volcanic smooth plains material that could be related to the activity that formed the bright vent.

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Woven Shadow

Part of the shadow of Saturn's moon Epimetheus appears as if it has been woven through the planet's rings in this Cassini image taken about a month and a half before the planet's August 2009 equinox.

Epimetheus itself is not shown, but the moon casts a shadow whose appearance varies based on the density of particles across the rings. See PIA11659 and PIA11660 to learn more.

The novel illumination geometry that accompanies equinox lowers the sun's angle to the ringplane, significantly darkens the rings, and causes out-of-plane structures to look anomalously bright and cast shadows across the rings. These scenes are possible only during the few months before and after Saturn's equinox, which occurs only once in about 15 Earth years. Before and after equinox, Cassini's cameras have spotted not only the predictable shadows of some of Saturn's moons (see PIA11657), but also the shadows of newly revealed vertical structures in the rings themselves (see PIA11665).

This view looks toward the northern, unilluminated side of the rings from about 45 degrees above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 26, 2009. The view was obtained at a distance of approximately 943,000 kilometers (586,000 miles) from Saturn. Image scale is 5 kilometers (3 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Planck's View of Orion

The big Hunter in the sky is seen in a new light by Planck, a European Space Agency mission with significant NASA participation. The long-wavelength image shows most of the constellation Orion, highlighting turbid clouds of cold material, where new stars are being stirred into existence.

This long-wavelength image covers a square region of 13 by 13 degrees (which is equivalent to 26 by 26 full moons). It is a three-color combination constructed from three of Planck's nine frequency channels: 30, 353 and 857 gigahertz.

The Planck mission is busy surveying the whole sky at longer wavelengths of light than we can see with our eyes, ranging from infrared to even longer-wavelength microwaves. It is collecting ancient light from the very beginning of time to learn more about the birth and fate of our universe. In the process, the mission is gathering data on our Milky Way galaxy that astronomers are using to see through cold pools of gas and dust, which block visible-light views of star formation.

The image shows one such region in our Milky Way, where stars are actively bursting to life. The much-photographed Orion nebula is the bright spot to the lower center. The bright spot to the right of center is around the Horsehead Nebula, so called because at high magnifications a pillar of dust resembles a horse's head. The whole view covers a square patch of sky equivalent to 26 by 26 moons.

The giant red arc of Barnard's Loop is thought to be the blast wave from a star that blew up inside the region about two million years ago. The bubble it created is now about 300 light-years across.

Note: The below photo, from the Digitized Sky Survey, is of the same region of Orion.

Photo credits: (Planck) ESA/LFI & HFI Consortia; (Digitized Sky Survey) STScI DSS

Evolution of the Hubble Sequence

This image created from data taken from both the NASA/ESA Hubble Space Telescope and the Sloan Digital Sky Survey demonstrates that the Hubble sequence six thousand million years ago was very different from the one that astronomers see today. The two sections show how many more peculiar shaped galaxies (marked Pec) are seen among distant galaxies, as opposed to among local galaxies. The data organization follows the Hubble tuning-fork classification scheme invented in 1926 by the same Edwin Hubble in whose honor the space telescope is named.

The top image represents the current - or local - Universe. Using their sample, researchers found that 3 percent of galaxies were elliptical (marked E), 15 percent lenticular (marked S0), 72 percent spiral (marked Sa to Sd, or SBb to SBd) and 10 percent peculiar (marked Pec).

The bottom image represents the make up of the distant galaxies (six thousand million years ago), showing a much larger fraction of peculiar galaxies. The census found 4 percent of distant galaxies were elliptical, 13 percent lenticular (S0), 31 percent spiral and 52 percent peculiar. This implies that many of the peculiar galaxies ultimately become large spirals. According to the "spiral rebuilding" hypothesis, devised by the astronomers François Hammer, Rodney Delgado-Serrano and their group, this is due to the large number of major, gas-rich galaxy mergers between galaxies that were previously labeled "peculiar" in the distant Universe. It is thought that the large Andromeda galaxy from our neighborhood formed in this manner.

In total, 116 local galaxies and 148 distant galaxies were sampled. Spiral galaxies are further classified by labels that characterize their appearance; for example, an SBd galaxy means that it is a spiral galaxy that has slightly looser "arms" than an SBa galaxy and a less prominent bulge.

These images were created from data that are part of large sky surveys undertaken by the NASA/ESA Hubble Space Telescope and the 2.5-meter telescope at Apache Point Observatory, New Mexico, USA (Sloan Digital Sky Survey).

Image credit: NASA, ESA, Sloan Digital Sky Survey, R. Delgado-Serrano and F. Hammer (Observatoire de Paris)

Comparison Views of "Mystic Mountain"

These two images of a pillar of star birth, three light-years high, demonstrate how observations taken in visible and infrared light by the NASA/ESA Hubble Space Telescope reveal dramatically different and complementary views of an object. The pair of images demonstrates how Hubble's new panchromatic view of the Universe shows striking differences between visible and infrared wavelengths. This turbulent cosmic pinnacle lies within a tempestuous stellar nursery called the Carina Nebula, located 7500 light-years away in the southern constellation of Carina. The images mark the 20th anniversary of Hubble's launch and deployment into an orbit around Earth.

[Left] This visible-light view shows how scorching radiation and fast winds (streams of charged particles) from super-hot newborn stars in the nebula are shaping and compressing the pillar, causing new stars to form within it. Infant stars buried inside fire off jets of gas that can be seen streaming from towering peaks. Streamers of hot ionized gas can be seen flowing from the ridges of the structure, and wispy veils of gas and dust, illuminated by starlight, float around it.

The dense parts of the pillar are resisting being eroded by radiation. The colors in this composite image correspond to the glow of oxygen (blue), hydrogen and nitrogen (green), and sulfur (red).

[Right] This near-infrared image shows a myriad of stars behind the gaseous veil of the nebula's background wall of hydrogen, laced with dust. The foreground pillar becomes semi-transparent because infrared light from the background stars penetrates through much of the dust. A few stars inside the pillar also become visible. Representative colors are assigned to three different infrared wavelength ranges.

Hubble's Wide Field Camera 3 observed the pillar in February/March 2010.

Photo credit: NASA, ESA, M. Livio and the Hubble 20th Anniversary Team (STScI)

Update: Hah! First! :) The Minister is pleased with himself that he discussed "Mystic Mountain" before the editors of the esteemed Astronomy Picture of the Day (even if it was by a mere few hours). However, the Minister also suggests to his readers that they visit APOD for another great picture and more information on this beautiful nebula.

Star Clusters and Nebulae

This colorful image from NASA's WISE (Wide-field Infrared Survey Explorer) is a view of an area of the sky over 12 times the size of the full Moon on the border of the constellations Sagittarius and Corona Australis. Two types of star clusters are visible in the image.

The wispy nebula running top to bottom of this image is a nearby star forming region. In visible light the dust within the nebula obscures and reflects the light of the stars within and behind it, giving rise to several cataloged nebula (NGC 6726, NGC 6727, NGC 6729, IC 4812). But here in infrared light we see the light of the dust itself as it is warmed by the light of the newborn stars in the cluster (green and red). We also see through the dust to peer at the stars nestled within (blue/cyan). This star cluster has been called the Coronet Cluster. It is located some 420 light-years from Earth, and stretches about 10 light-years across. The Coronet Cluster is a relatively loose cluster of only a few dozen stars, many of which are only a few million years old.

Just to the left of center is a very different kind of star cluster. NGC 6723 is a globular star cluster located some 29,000 light-years away from Earth, and spans about 65 light-years in size. Globular star clusters contain hundreds of thousands to millions of stars and orbit around the Galaxy in a spherical halo surrounding it. These are some of the oldest stars in the Universe, over 10 billion years old.

All four infrared detectors aboard WISE were used to make this image. Color is representational: blue and cyan represent infrared light at wavelengths of 3.4 and 4.6 microns, which is dominated by light from stars. Green and red represent light at 12 and 22 microns, which is mostly light from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

Note: I've added this annotated photograph of the area to help people identify the different nebulae and star clusters in the photograph.

Photo credit: Loke Kun Tan (StarryScapes)

Methane-Free Exoplanet GJ 436b

An unusual, methane-free world is partially eclipsed by its star in this artist's concept. NASA's Spitzer Space Telescope has found evidence that a hot, Neptune-sized planet orbiting a star beyond our sun lacks methane -- an ingredient common to many planets in our own solar system.

Models of planetary atmospheres indicate that any world with the common mix of hydrogen, carbon and oxygen, and a temperature up to 1,000 Kelvin (1,340 degrees Fahrenheit) should have a large amount of methane and a small amount of carbon monoxide.

The planet illustrated here, called GJ 436b is about 800 Kelvin (or 980 degrees Fahrenheit) -- it was expected to have methane but Spitzer's observations showed it does not.

The finding demonstrates the diversity of exoplanets, and indicates that models of exoplanetary atmospheres need to be revised.


How to Measure Exoplanet Light

The plots in Figure 1 show light from the distant planet, GJ 436b, and its star, as measured at six different infrared wavelengths. Astronomers use telescopes like Spitzer to measure the direct light of distant worlds, called exoplanets, and learn more about chemicals in their atmospheres.

The technique involves measuring light from an exoplanet and its star before, during and after the planet circles behind the star. (The technique only works for those planets that happen to cross behind and in front of their stars as seen from our point of view on Earth.) When the planet disappears behind the star, the total light observed drops, as seen by the dips in these light curves. This same measurement is repeated at different wavelengths of light. In this graph, the different wavelengths are on the vertical axis, and time on the horizontal axis. Those dips in the total light tell astronomers exactly how much light is coming from the planet itself.

As the data demonstrate, the amount of light coming off a planet changes with different wavelengths. The differences are due to the temperature of a planet as well as its chemical makeup. In this case, astronomers were able to show that GJ 436b lacks the common planetary ingredient of methane.

Image credit: NASA/JPL-Caltech

Dante Crater

Highlands terrain inside the Dante Crater Constellation Site. A portion of LROC NAC image M121044107R, 580 m across.

Only a handful of humans have ever seen the farside of the Moon. In the future, human explorers near Dante crater in the farside highlands will be searching for samples of the Moon's most ancient, primordial crust (anorthosites like the famous Apollo sample 15415). There was a time after the Moon's formation when the entire surface was covered by an ocean of magma; the upper layer of this magma ocean crystallized to form a global layer of anorthosite. Since that time, impacts and other geological processes have broken and churned the surface, but this area may posses significant amounts of these original rocks. Pristine lunar anorthosites are relatively rare in the Apollo sample collections; with enough samples we could learn when the primordial crust started to form and when it was complete. Scientists would also like to learn the rate of cratering during this early period in the Moon's formation. The ancient regolith contains rocks that formed from impact melt, which can be dated to learn when the impact even that created them occurred. Did the large impacts form across a broad range of time - or in one large spike? Collecting samples from this ancient highland area would help use better understand this early period in Solar System development, with profound implications for understanding the early history of Earth.

Portion of LROC WAC image M118668951M, which covers Dante Crater itself. The region of M121044107R (above) is to the west of this scene.

The Dante region has abundant aluminum and calcium-rich regolith that is available for in-situ resource utilization, allowing explorers to extend their stay in this region by processing the local materials to produce oxygen and fuel while building habitats and other structures.

Explorers at this location would never see the Earth. They would instead see the unobstructed vista of the Milky Way above them. The Sun would rise and set once a month, but all communications back to Earth would have to be via orbiting relay satellites. However, with the bulk of the Moon shielding this location from the bright lights and radio waves of the Earth, the central farside highlands are an optimal location for astronomy, especially observations of the low-frequency radio sky.

Photo credit: NASA/GSFC/Arizona State University

Cleaning and Aluminizing the Hale Telescope Mirror

This is a fascinating time-lapse video (with narration) that shows the process of the cleaning and aluminizing of the Hale Telescope mirror, which is located at the Palomar Observatory. The mirror is first removed from the telescope and moved to the area inside the observatory where it will be cleaned. Near the end of the cleaning process, the old coat of aluminum is removed from the mirror, allowing one to see the honeycomb structure of the underside. When the mirror is ready, a new coat of aluminum is evaporated onto the glass.

The Belet Region of Titan

The Cassini spacecraft looks at Belet, a dark region on Saturn's largest moon, Titan.

This large region on the moon has a low albedo, meaning it diffusely reflects little light. See PIA11149 to learn more. This view looks toward the trailing hemisphere of Titan (5,150 kilometers, or 3,200 miles across). North on Titan is up and rotated 2 degrees to the right.

The image was taken with the Cassini spacecraft narrow-angle camera on Jan. 15, 2010 using a spectral filter sensitive to wavelengths of near-infrared light centered at 938 nanometers. The view was acquired at a distance of approximately 1.2 million kilometers (746,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 51 degrees. Image scale is 7 kilometers (4 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

IC 1795 by WISE

This image from NASA's Wide-field Infrared Survey Explorer, or WISE, is a view within the constellation Cassiopeia of another portion of the vast star forming complex that makes up part of the Perseus spiral arm of the Milky Way Galaxy. Two of the previously released images from WISE are also a part of the same star formation complex of nebulae: The Soul Nebula (PIA13014) and Maffei 1 and 2 (PIA12865). A distinct star forming region is visible in the bottom right corner of this image, called IC 1795. Most of this region appears dark and relatively devoid of stars in photographs taken in visible light. This is because of the obscuring dust, but that same dust glows brightly in the infrared images obtained by WISE. The cloud is located just over 6,000 light-years away from Earth. Stars forming in this image are all relatively young, on the order of millions of years. That is young in comparison to stars like the Sun, which is nearly 5 billion years old.

This image covers an area of sky larger than 12 full Moons. All four infrared detectors aboard WISE were used to make this image. Color is representational: blue and cyan represent infrared light at wavelengths of 3.4 and 4.6 microns, which is dominated by light from stars. Green and red represent light at 12 and 22 microns, which is mostly light from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

The Apollo 15 Lunar Laser Ranging Retroreflector

The Apollo 15 Lunar Laser Ranging RetroReflector (LRRR) array is one of four such working arrays on the surface of the Moon. As the largest (105 x 65 cm in size) it serves as the primary target for laser ranging to the Moon. In this calibrated image it appears as the (circled) tiny white rectangular feature farthest to center left (near the edge of the original NAC image). The distance to these retroreflectors from the Earth can be and is still routinely measured to the centimeter level or better, and their relative positions are known to a similar level. Such measurements can be used for several purposes, such as precisely determining the orientation and orbit of the Moon, testing gravitation and general relativity theories, and for establishing a highly precise latitude and longitude coordinate frame for the Moon. The image width is 391 meters, with a pixel width of 52 cm. Subset of NAC frame M111578606LE [NASA/GSFC/Arizona State University].

The close-up here of the Apollo 15 landing site (26.1°N 3.6°E) is a portion of one of several LROC narrow angle camera (NAC) images that show the site (see earlier released image). Although near the edge of the NAC image M111578606LE, this close-up (about 391 meters across, at 52 cm/pixel) shows many pieces of hardware left on the surface by the Apollo 15 astronauts, including of interest here the Apollo 15 lunar Laser Ranging RetroReflector (LRRR) array. It was placed on the Moon by astronaut David Scott on 1971 July 31. A photograph of a portion of the LRRR taken by Scott is shown below. The Apollo 15 array is one of four usable such arrays on the Moon. The others are at the Apollo 11 and Apollo 14 sites, and on the Lunokhod 2 rover (see here for information on Lunokhod 2).

A portion of the Apollo 15 lunar laser ranging retroreflector array, as placed on the Moon and photographed by D. Scott [NASA photo AS15-85-11468].

Finding your position on the Moon can be tricky. Since the 17th century, the Moon's coordinates have been measured in what is now known as the “mean Earth/polar axis system,” or ME system for short. This is a latitude and longitude system where the mean (average) direction of the Earth over time defines the 0° longitude, or prime meridian, and the average direction of the Moon’s polar axis defines 90° north and south latitude. However, in order to effectively use such a system, it is necessary to assign latitude and longitude to a set of points on the Moon. This is where the LRRR arrays come in. Over the years since they were emplaced on the Moon, lunar laser ranging (LLR) observations of these arrays from several sites on the Earth have been processed and the relative positions of these arrays determined to the centimeter level. These relative coordinates have been converted to absolute latitude and longitude coordinates according to the above definition of the ME system, and thus are now the points on the Moon whose positions are most accurately known.

However, for the general purpose of locating things on the Moon, knowing the positions of only four points is not particularly useful. Therefore an important step in being able to use the data being returned from the LRO mission, as well as from previous U. S. and international missions, is to connect those datasets to the LLR coordinates. For LRO, a first step will be to determine the coordinates of LROC images and digital elevation models (DEMs) (see here) covering the LRRR sites). A second step will be to compare the positions of LRO Lunar Orbiter Laser Altimeter (LOLA) data to these images and DEMs in order to make sure that the global LOLA dataset is connected to these coordinates. The final step will be to assure that all other LROC and eventually even past U.S. and international mission data are in the same LLR coordinate frame. This will assure that lunar datasets will be in the same coordinate frame and that such data can be used together, consistently, for human exploration planning and associated science activities.

For more information on connecting lunar datasets together, read this 2010 Lunar and Planetary Science Conference abstract.

Explore the rest of the Apollo 15 landing site area!

Stories and Photos of Interest

The Minister finds himself awash in an embarrassment of riches. Due to a tight schedule, he is only able to do one post per day for his MinSEx blog. Alas, the number of stories and photos that he might be able to blog about is a much greater number. Thus, he's going to provide a weekly list of some (but not all) of the stories and photos he's come across in the past week that he thinks his readers might find of interest. Sorted by topic:

The Sun:
Bright Points on the Quiet Sun (Recommended!)

Earth:
PIA13041: NASA's AIRS Instrument Captures Ash Cloud from Icelandic Volcano
PIA13046: NASA Satellite Images Provide Insights Into Iceland Volcanic Plume
PIA13033: Hale Telescope, Palomar Observatory

Moon:
PIA13039: Rimae Prinz Region - Constellation Region of Interest
PIA13038: Exposed Fractured Bedrock in the Central Peak of the Anaxagoras Crater

Saturn:
PIA12613: Brilliant Blip Beyond Saturn
PIA12579: Dione Polar Maps - February 2010
PIA12578: Dione Polar Maps - February 2010
PIA12577: Map of Dione - February 2010
PIA12612: In the Arc
PIA12576: Lightning Flashing on Saturn
PIA12575: First Lightning Flashes on Saturn
PIA12611: Up and Down Tethys
PIA12610: Lost Among Stars

Space Exploration:
A Large Space Station Over Earth
Damage to Apollo 13

Black Holes:
Diagnosis Murder: Study Shows Supermassive Black Holes May Strip Galaxies of Life

Galaxies:
NGC 4651: The Umbrella Galaxy
Explained: Why Many Surveys of Distant Galaxies Miss 90% of Their Targets

Palomar Observes the Exoplanets Around HR 8799

Note: I originally discussed the discovery of the three exoplanets orbiting around star HR 8799 back in November 2008 in my post Four Exoplanets Seen.

This image shows the light from three planets orbiting a star 120 light-years away. The planets' star, called HR8799, is located at the spot marked with an "X."

This picture was taken using a small, 1.5-meter (4.9-foot) portion of the Palomar Observatory's Hale Telescope, north of San Diego, California. This is the first time a picture of planets beyond our solar system has been captured using a telescope with a modest-sized mirror -- previous images were taken using larger telescopes.

The three planets, called HR8799b, c and d, are thought to be gas giants like Jupiter, but more massive. They orbit their host star at roughly 24, 38 and 68 times the distance between our Earth and sun, respectively (Jupiter resides at about 5 times the Earth-sun distance).

Photo credit: NASA/JPL-Caltech/Palomar Observatory

Messier 66 by Hubble

Hubble has snapped a spectacular view of the largest "player" in the Leo Triplet, a galaxy with an unusual anatomy: it displays asymmetric spiral arms and an apparently displaced core. The peculiar anatomy is most likely caused by the gravitational pull of the other two members of the trio.

The unusual spiral galaxy, Messier 66, is located at a distance of about 35 million light-years in the constellation of Leo. Together with Messier 65 and NGC 3628, Messier 66 is one third of the Leo Triplet, a trio of interacting spiral galaxies, part of the larger Messier 66 group. Messier 66 wins out in size over its fellow triplets - it is about 100 000 light-years across.

Messier 66 is the proud owner of exclusive asymmetric spiral arms which seem to climb above the galaxy's main disc and an apparently displaced nucleus. This asymmetry is unusual; most often, dense waves of gas, dust and newly born stars wind about the galaxy's center in a symmetric way. Astronomers believe that Messier 66's once orderly shape has most likely been distorted by the gravitational pull of its two neighbors.

Hubble has imaged Messier 66's striking dust lanes and bright star clusters along the spiral arms in fine detail with the Advanced Camera for Surveys. Star clusters - pictured in the blue and pinkish regions of the image - are key tools for astronomers since they are used as indicators of how the parent galaxies assembled over time.

Messier 66 boasts a remarkable record of supernovae explosions. The spiral galaxy has hosted three supernovae since 1989, the latest one occurring in 2009. A supernova is a stellar explosion that may momentarily outshine its entire host galaxy. It then fades away over a period lasting several weeks or months. During its very short life the supernova radiates as much energy as the Sun would radiate over a period of about 10 thousand million years.

Photo credit: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration. Acknowledgment: Davide De Martin and Robert Gendler

The Rosette Nebula by Herschel

This image from the Herschel Space Observatory shows most the cloud associated with the Rosette nebula, a stellar nursery about 5,000 light-years from Earth in the Monoceros, or Unicorn, constellation. Herschel collects the infrared light given out by dust. The bright smudges are dusty cocoons containing massive embryonic stars, which will grow up to 10 times the mass of our sun. The small spots near the center of the image are lower mass stellar embryos. The Rosette nebula itself, and its massive cluster of stars, is located to the right of the picture.

This image is a three-color composite showing infrared wavelengths of 70 microns (blue), 160 microns (green), and 250 microns (red). It was made with observations from Herschel's Photoconductor Array Camera and Spectrometer and the Spectral and Photometric Imaging Receiver instruments.

Photo credit: ESA and the PACS, SPIRE & HSC consortia, F. Motte (AIM Saclay,CEA/IRFU - CNRS/INSU - U.ParisDidedrot) for the HOBYS key programme

Dione and Titan

Saturn's moon Dione passes in front of the larger moon Titan, as seen from the Cassini spacecraft.

This image is part of a mutual event sequence in which one moon passes close to or in front of another. Such observations help scientists refine their understanding of the orbits of Saturn's moons. See PIA11692 to watch a movie of a mutual event.

Lit terrain seen here is on the anti-Saturn side of Dione (1,123 kilometers, or 698 miles across) and the leading hemisphere of Titan (5,150 kilometers, or 3,200 miles across).

The image was taken in visible blue light with the Cassini spacecraft narrow-angle camera on March 12, 2010. The view was obtained at a distance of approximately 2.2 million kilometers (1.4 million miles) from Dione and 3.6 million kilometers (2.2 million miles) from Titan. Scale in the original image was 13 kilometers (8 miles) per pixel on Dione and on 21 kilometers (13 miles) per pixel Titan. The image has been magnified by a factor of 1.5 and contrast-enhanced to aid visibility.

Photo credit: NASA/JPL/Space Science Institute

Graben and Pyroclastics in SW Mare Humorum

Two small black arrows on today's image show the location of a small graben. A degraded impact crater (108 m in diameter) can be seen centered on the graben between the arrows. Graben are extensional tectonic features formed by the downward movement of a crustal block between two normal faults. This small graben is parallel to a much larger graben (Rima Doppelmayer I) which is 1100 m wide and located only 800 m to the west. You can also see other small graben that are parallel to Rima Doppelmayer I. All of these graben may have formed during the episode of regional extension associated with the final filling of Mare Humorum with dense mare basalt deposits.

Finally, it should be noted that the entire area shown in the image is mantled by a relatively thick (greater than 10 m) deposit of pyroclastic glass. It has been suggested that pyroclastic debris would be an excellent lunar resource, and that pyroclastic deposits would be prime sites for the establishment of lunar bases.

Photo credit: NASA/GSFC/Arizona State University

IC 342 by WISE

The spiral beauty, called IC 342 and sometimes the "hidden galaxy," is shrouded behind our own galaxy, the Milky Way. Stargazers and professional astronomers have a hard time seeing the galaxy through the Milky Way's bright band of stars, dust and gas. WISE's infrared vision cuts through this veil, offering a crisp view.

In a spiral galaxy like IC 342, dust and gas are concentrated in the arms. The denser pockets of gas trigger the formation of new stars, as represented here in green and yellow. The core, shown in red, is also bursting with young stars, which are heating up dust. Stars that appear blue reside within our Milky Way, between us and IC 342.

This galaxy has been of great interest to astronomers because it is relatively close. However, determining its distance from Earth has proven difficult due to the intervening Milky Way. Astronomer Edwin Hubble first thought the galaxy might belong to our own Local Group of galaxies, but current estimates now place it farther away, at about 6.6 to 11 million light-years.

This image was made from observations by all four infrared detectors aboard WISE. Blue and cyan represent infrared light at wavelengths of 3.4 and 4.6 microns, which is primarily light from stars. Green and red represent light at 12 and 22 microns, which is primarily emission from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

Lava Flows on Venus' Idunn Mons

This figure shows the volcanic peak Idunn Mons (at 46 degrees south latitude, 214.5 degrees east longitude) in the Imdr Regio area of Venus. The topographic backbone derives from data obtained by NASA's Magellan spacecraft, with a vertical exaggeration of 30 times. Radar data (in brown) from Magellan has been draped on top of the topographic data. Bright areas are rough or have steep slopes. Dark areas are smooth.

The colored overlay [above] shows the heat patterns derived from surface brightness data collected by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS), aboard the European Space Agency's Venus Express spacecraft. Temperature variations due to topography were removed. The brightness signals the composition of the minerals that were changed due to lava flow. Red-orange is the warmest area and purple is the coolest. The warmest area is centered on the summit, which stands about 2.5 kilometers (1.6 miles) above the plains, and the bright flows that originate there. Idunn Mons has a diameter of about 200 kilometers (120 miles).

The spectrometer data was collected from May 2006 to the end of 2007. A movie featuring 360-degree views of the volcano is based on the same data and can be viewed at JPL's Multimedia.

Photo credit: NASA/JPL-Caltech/ESA

Note: For more information, see New Evidence for Recent Volcanism on Venus, at the ESA/Venus Express website.

Dione's Wispy Terrain

Wispy terrain winds across the trailing hemisphere of Saturn's moon Dione in this Cassini view taken during the spacecraft's Jan. 27, 2010 non-targeted flyby.

Cassini came within about 45,000 kilometers (28,000 miles) of the moon during this flyby, but this image was acquired at a distance of approximately 137,000 kilometers (85,000 miles) from Dione. See PIA06163 for an older, closer view of Dione's wispy fractures. This view looks toward the anti-Saturn side and trailing hemisphere of Dione (1,123 kilometers, or 698 miles across). North on Dione is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 27, 2010. The view was obtained at a Sun-Dione-spacecraft, or phase, angle of 38 degrees. Image scale is 819 meters (2,687 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Each Crater Tells a Story

Browsing around the Flamsteed Constellation region of interest, you might notice that a lot of the craters here have odd features, including flat floors, raised floors, or rings that look like one crater nested within another. In the image above, the crater in the middle top displays a ring within its main (degraded) rim, and the crater just below it has a flat floor, compared to the typical bowl-shaped craters in the surroundings. These type of features occur when a crater forms partly in rocky material and partly in regolith. The term regolith refers to all of the fragmental material - dust and rocks of all sizes - that covers the Moon's surface and is created by impact events which continually pulverize the bedrock. When planning for lunar surface activities, engineers were concerned that this dusty, sandy surface wouldn't be stable for the spacecraft and Apollo astronauts that were to land there, so scientists worked out methods to estimate the thickness of the regolith ahead of time. Using images from Lunar Orbiter and laboratory experiments with a high-velocity vertical gun, a relationship between regolith thickness and the shape of a crater was developed. If the regolith is thin compared to the depth of the crater, the crater forms an inner ring. If the regolith is a little thicker, the crater develops a flat floor, and if thicker still then the crater is bowl-shaped.

WAC [Wide Area Camera] monochrome observation of the Flamsteed Constellation region of interest. Arrow indicates location of NAC [Narrow Area Camera] image above and Flamsteed crater (20 km in diameter) is at the lower left. Scene width is 87 km; image M117779352ME [NASA/GSFC/Arizona State University].

The crater shapes in the Flamsteed Constellation region of interest demonstrate that the regolith is very thin (on average just a couple meters thick). This is because this is the site of some of the youngest volcanism on the Moon, and since the surface is younger, it hasn't had as much time to get beat up by impacts. Visiting this site with human explorers would provide a good opportunity to sample the bedrock beneath this thin regolith, and could give insight into the duration of volcanic activity on the Moon, and the evolution of lunar volcanism as the Moon aged and cooled. Astronauts could also visit the nearby Surveyor 1 site and check on the condition of America's first soft lander.

Photo credit: NASA/GSFC/Arizona State University

Shiveluch Volcano Erupting

Shiveluch Volcano in Kamchatka, Siberia, Russia, is one of the frequently active volcanoes located in eastern Siberia. In this composite image, brownish ash covers the southern part of the mountain, under an ash-laden vertical eruption plume. Red areas are hot-spots seen on ASTER's thermal infrared bands, and are related to lava flows. The image was acquired March 26, 2010, and is located at 56.6 degrees north latitude, 161.3 degrees east longitude. The image covers an area of 17.7 x 21.2 km.

Photo credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Saturn Ring Spokes and the Shadow of Mimas

Bright spokes and the shadow of a moon grace Saturn's B ring in this Cassini spacecraft image.

Spokes are radial markings scientists continue to study, and they can be seen here stretching from the far left to upper right of the image. Spokes appear bright when they are viewed at phase, or Sun-Saturn-spacecraft, angles higher than about 45 degrees. This image was taken at a phase angle of 50 degrees. See PIA11144 and PIA08288 to learn more.

The moon Mimas is not shown here, but its shadow appears on the rings near the top of the image. The novel illumination geometry that accompanies equinox lowers the sun's angle to the ringplane, significantly darkens the rings, and causes out-of-plane structures to look anomalously bright and cast shadows across the rings. These scenes are possible only during the few months before and after Saturn's equinox, which occurs only once in about 15 Earth years. Before and after equinox, Cassini's cameras have spotted not only the predictable shadows of some of Saturn's moons (see PIA11657), but also the shadows of newly revealed vertical structures in the rings themselves (see PIA11665).

This view looks toward the northern, sunlit side of the rings from about 9 degrees above the ringplane. The image was taken using a compression scheme that reduces the image file size on the spacecraft's data recorder, resulting in the rings' slightly pixelated appearance.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on Jan. 11, 2010. The view was acquired at a distance of approximately 611,000 kilometers (380,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 50 degrees. Image scale is 66 kilometers (41 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Soul Nebula (IC 1848-W5) by WISE

This WISE mosaic is of the Soul Nebula (a.k.a. the Embryo Nebula, IC 1848, or W5). It is an open cluster of stars surrounded by a cloud of dust and gas over 150 light-years across and located about 6,500 light-years from Earth in the constellation Cassiopeia, near the Heart Nebula (partially seen in the WISE image of Maffei 1 & 2).

The cluster of stars, IC 1848, formed about a million years ago from the material of the nebula. Winds and ultraviolet light from these young stars are excavating a cavity in the cloud. Parts of the cloud that are more dense than their surroundings are being eroded more slowly and form giant towers, or pillars of dust and gas, which all point toward the central star cluster. It's reminiscent of the landscape of Badlands National Park in South Dakota. Material at the interior edges of the cavity is also being compressed by the winds and radiation from the star cluster. This triggers new star formation in those areas. The pillars inside the Soul Nebula are each about 10 light-years tall and have stars forming at their tips.

All four infrared detectors aboard WISE were used to make this image. Color is representational: blue and cyan represent infrared light at wavelengths of 3.4 and 4.6 microns, which is primarily light from stars. Green and red represent light at 12 and 22 microns, which is primarily emission from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

Yin Yang Iapetus

The two-toned surface of Saturn's moon Iapetus is demonstrated in the dark region of the moon visible on the top left and the bright crater in the lower right of this Cassini portrait.

See PIA11690 to learn more about the brightness dichotomy on Iapetus.

The moon's oblate shape is also visible here. This view looks toward the Saturn-facing side of Iapetus (1,471 kilometers, or 914 miles across). North on Iapetus is up and rotated 35 degrees to the right.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 23, 2010. The view was obtained at a distance of approximately 1.6 million kilometers (994,000 miles) from Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 51 degrees. Image scale is 9 kilometers (6 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

The Trapezium Cluster in the Orion Nebula

A colony of hot, young stars is stirring up the cosmic scene in this new picture from NASA's Spitzer Space Telescope. The image shows the Orion nebula, a happening place where stars are born. The young stars dip and peak in brightness due to a variety of reasons. Shifting cold and hot spots on the stars' surfaces cause brightness levels to change, in addition to surrounding disks of lumpy planet-forming material, which can obstruct starlight. Spitzer is keeping tabs on the young stars, providing data on their changing ways.

The hottest stars in the region, called the Trapezium cluster, are bright spots at center right. Radiation and winds from those stars has sculpted and blown away surrounding dust. The densest parts of the cloud appear dark at center left.

This image was taken after Spitzer's liquid coolant ran dry in May 2009, marking the beginning of its "warm" mission. Light from the telescope's remaining infrared channels has been color-coded: 3.6-micron light is blue and 4.5-micron light is orange.

Photo credit: NASA/JPL-Caltech