Uncategorized

A Piece of Mars: Sometimes I just want to show the interior of a dune field, because it's full of waves: ripples and dune crests, slip faces, all of which signs of movement. The dunes in this 0.67x0.47 km (0.41x0.29 mi) view have been made by two winds: one blowing from the top of the frame, and a more-recently-active one blowing from the right. Together, these two winds (and gravity) push this sand between a series of hills and down into Coprates Chasma, one of the longest canyons on Mars. (HiRISE ESP_035278_1655, NASA/JPL/Univ. of Arizona) read more ❯

A Piece of Mars: This 0.48x0.27 km (0.3x0.17 mi) scene shows a rotund barchan dune. Can you tell from looking at it where on Mars it might be? To me the most obvious feature are the bumpy piles at the bottom of the slip face (at the foot of the dune on the right). They're probably the remains of avalanches that occurred when there was still winter frost on the dunes. This is a summertime image, so the frost is long gone and the wind is reworking the dune, trying to erase signs of the cold season avalanches. This sort... read more ❯

This morning, NASA's Cassini spacecraft obtained the first closeup images of Saturn's innermost moon, Pan. The images show a peculiar body shaped like a "flying saucer". Pan occupies a unique position in the rings, at the center of the 300-km wide Encke Gap. As best we can tell, Pan probably started its life as a more spherical moon, but it subsequently swept up a thick equatorial belt of ring-dust. A smattering of crevasses and craters across the surface add to our view of a moon that has endured... read more ❯

In May 2016, Michael Gillon and his team announced the discovery of three Earth-sized exoplanets around TRAPPIST-1, an ultra cool M-dwarf star, using the small TRAPPIST telescope at ESO-La Silla, Chile. It was an exciting discovery—yet on that day no one could possibly have imagined that less than a year later they would make another significant discovery involving the same system. But here we are: today, they announced in Nature the discovery of seven potentially habitable Earth-like worlds. The star, named TRAPPIST-1, is a fairly inconspicuous star in our Milky Way.... read more ❯

A Piece of Mars: Sometimes in the floors of small craters, the wind blows in from several directions to produce odd polygon-shaped dunes that look like crochet (maybe Mars is making sweaters for its craters - it is, after all, a cold place). This "sweater" segment is 480x270 m (0.3x0.17 mi) in size (the "stitches" are ~20 m, or 66 ft, across). The smaller interior lines are younger windblown features, that are superposed on the larger structures - their alignment is strongly controlled by the topography of the larger polygonal "stitches". (HiRISE ESP_017833_1975, NASA/JPL/Univ. of Arizona) read more ❯

Using a combination of space telescope data, as well as recent data acquired with the SOFIA Airborne telescope and lab experiments, a team of astronomers including researchers from the SETI Institute and Jet Propulsion Laboratory  have revealed the presence of dust of exogenic origin at the surface of dwarf planet Ceres. This contamination likely stems from a dust cloud formed in the outer part of the main belt of asteroids following a collision in recent times. That study challenges the relationship proposed between Ceres and asteroids in the C spectral class and instead suggests an origin of this dwarf planet... read more ❯

A Piece of Mars: A low, broad dune occupies the center of this 800x450 m (0.5x0.28 mi) scene, blown by a dominant wind towards the lower left. The slip face on the lee side has several small avalanches, formed as the slope oversteepens (this is how dunes crawl along the surface). Upwind, among other fainter lines, is a prominent bright line: it is a former slip face of this dune, possibly formed from a thick accumulation of bright dust (maybe there was a big dust storm that year). Farther upwind, another dune slowly approaches. (HiRISE ESP_033955_2065, NASA/JPL/Univ. of Arizona) read more ❯

I co-organized a session for the AGU 2016 meeting entitled "P42A: Solar System Small Bodies: Asteroids, Satellites, Comets, Pluto, and Charon". Below the info on the session and the schedule. We have three invited talks that will describe the New Horizons data of Charon, color of Kuiper Belt Object from a ground-based survey and a theoretical study of the formation of the asteroid belt. Abstract: The composition and physical properties of Small Solar System Bodies (SSSBs), asteroids and dwarf planets, remnants of the formation of planets, are key to better understand our solar system. Increased knowledge of their surface properties and their potential... read more ❯

AGU Fall meeting is starting tomorrow. I co-organized a session entitled "Detection and Direct Imaging of Habitable Exoplanets: Progress and Future" to discuss the potential of new and future facilities and modeling efforts designed to detect, image and characterize habitable exoplanets, studying their formation, evolution and also the existence of possible biospheres.  Topics that are covered in this session include signs of exoplanet habitability and global biosignatures that can be sought with upcoming instrumentation; instrument requirements and technologies to detect these markers; strategies for target selection and prioritization; and impacts of planetary system properties, ground-based and space telescope architectures. We have two invited... read more ❯

It was a tough night … one in which any dreams we may have had of “American exceptionalism” were crushed. Instead of serving, as it has so nobly, for more than two centuries as a beacon of hope and light to people everywhere, this nation will instead see our first African-American president hand the keys to the White House to a low-grade reality TV star who is endorsed by David Duke and the KKK, “alt-right” crazies, and American Nazis. To the horror of many of us, our next president will be someone who explicitly rejects science, reason, and the values we... read more ❯