Latest Posts

Stealth bomber dunes

ESP_027854_2150_0.4xA piece of Mars: These dunes look strangely triangular, a little bit like a flock of stealth bombers. Why? They’re two-faced barchans. Each flat face is an avalanche slope that faces downwind, formed by one of two distinct wind patterns that blow in this area (probably seasonally). Dunes like this can form on Earth, but the older slip face tends to be quickly erased as the winds change. (HiRISE ESP_027854_2150, NASA/JPL/Univ. of Arizona)

Hot Jupiter-esque Discovery Hints at Planet Formation

Keck Observatory press release  published on August 13 2015

MAUNAKEA, Hawaii – A team of astronomers discovered a Jupiter-like planet within a young system that could serve as a decoder ring for understanding how planets formed around our sun. The W. M. Keck Observatory on Maunakea, Hawaii confirmed the discovery. The findings were headed by Bruce Macintosh, a professor of physics at Stanford University,  and show the new planet, 51 Eridani b, is one million times fainter than its parent star and shows the strongest methane signature ever detected on an alien planet, which should yield additional clues as to how the planet formed. The results are published in the current issue of Science.

CREDIT: W. M. KECK OBSERVATORY, CHRISTIAN MAROIS, NRC CANADA Image of 51 Eri b as seen by the NIRC2 instrument on Keck Observatory's Keck II telescope. The bright central star has been mostly removed by a mask to enable the confirmation of the exoplanet one million times fainter.

CREDIT: W. M. KECK OBSERVATORY, CHRISTIAN MAROIS, NRC CANADA
Image of 51 Eri b as seen by the NIRC2 instrument on Keck Observatory’s Keck II telescope. The bright central star has been mostly removed by a mask to enable the confirmation of the exoplanet one million times fainter.

(more…)

How GPI Works to See Planets

I sometimes compare the challenge of directly detecting a Jupiter orbiting a nearby star to finding a glowing needle in a haystack.  Oh, and by the way, the haystack is on fire.

It’s about as hard as seeing a candle a foot away from a spotlight (1 million candlepower) at a distance of 100 miles.

Why is doing this so difficult?  There are three primary reasons: (more…)

What is burying what?

ESP_041134_1720_1.0xA piece of Mars: There’s an egg-shaped plateau here (the whole scene is 480×270 m or 525×295 yd across, the “egg” is ~100 m long). It’s partly covered by dunes that have extended across it. Or were the dunes there first and it buried them? Probably the former, but you can try to convince yourself either way. What do you think? (HiRISE ESP_041134_1720, NASA/JPL/Univ. of Arizona)

Dust devils and wind scours on ripples on dunes

ESP_040885_1295_1.0xA piece of Mars: So much wind. There are dark swirly tracks of dust devils that have passed by, ripples covering dunes, wind scours around rocks, and of course dunes. Dune crests have a different color than other regions: are they less covered in dust? made of a more grayish sand that is more easily blown up the dune by the wind? or both? (HiRISE ESP_040885_1295, NASA/JPL/Univ. of Arizona)

Abscicon 2015 in Chicago: Finding Habitable Worlds and Life Beyond the Solar System

What could the near future hold for detecting habitable, and eventually inhabited, extrasolar planets?

That’s the question we asked together with my colleagues Victoria Meadows, A. Mandell and Margaret Turnbull. To this purpose we organized a session for the Astrobiology Science Conference 2015 (#abscicon2015) held at Chicago on June 15-19 entitled “Finding Habitable Worlds and Life Beyond the Solar System”. The goal of our session was to provide a venue to discuss the prospective in the near future to detect habitable extrasolar planets.

AbSciCon2015_logo_1

(more…)

Frosty dunes

ESP_041433_2650_1.0xA piece of Mars: In this image (0.96×0.54 km or 0.6×0.33 mi), it’s late winter and the sun is barely above the horizon here near the north pole. The dunes are covered in winter frost, most of which is CO2 ice (also known as dry ice). The dark regions are those facing the sun, where the ice has started to sublimate, revealing the dark sand below. (HiRISE ESP_041433_2650, NASA/JPL/Univ. of Arizona)

Telling Pluto’s Story, One Fragment at a Time

The Pluto System

Pluto and Charon are in the middle, orbiting around their common center of mass. The four smaller moons orbit around them.

When you begin a new research project, you usually have expectations about where it will lead. Most projects take you or less to the expected destination. Some go nowhere. However, every now and then a project picks you up and makes you feel like you’re just coming along for the ride.

Today, in the journal Nature, we have published the results of a research project that fits solidly into the third category.

Our original plan was straightforward. We had recently discovered two small moons of Pluto, now known as Kerberos and Styx. We wanted to publish a short discovery paper that would just cover the basics: How did we find the moons? What are their orbits? How big are they? What are the implications of the discovery?

The Pluto system had other ideas. (more…)

Small dunes on Mars

ESP_041089_1980_0.75xA piece of Mars: These dunes are some of the smallest on Mars. The smallest in this frame is ~150 m long (492 ft). But the smallest Earth dunes are ~20 m across. Why are they so much bigger on Mars? The air is thinner, so the wind has to blow stronger to lift sand grains. So once the sand is moving, it goes fast – and therefore goes farther before it lands. This makes for a bigger dune. (HiRISE ESP_41809_1890, NASA/JPL/Univ. of Arizona)

The looming dune

ESP_027432_1350_1.0xA piece of Mars: this 0.96×0.54 km (0.6×0.33 mi) scene shows a large, rippled dune that is slowly marching towards the upper right. The smooth striped band running from upper left to lower right is the slip face, where sand pushed by the wind eventually avalanches. Smaller scars show where slope failures (little landslides) have formed. (HiRISE ESP_027432_1350, NASA/JPL/Univ. of Arizona)