Latest Posts

Dune trails

A Piece of Mars: The dark dunes in this 0.96×0.54 km (0.60×0.34 mi) scene are slowly migrating towards the lower left. Look closer and you’ll see brighter ripples between the dunes – the biggest ones are ~8m (26 ft) apart. They form trains in the wake of the dunes. Why? This is where the dunes previously marched on by, obliterating the ripples as they went. Ripples form again after the dunes pass by, growing in size and regularity with time. (HiRISE ESP_01746_2570, NASA/JPL/Univ. of Arizona)

NASA Mars acronym fun


Today I’ve got something different. Today NASA announced the discovery of hydrated salts in some dark slope features that form during the spring on Mars. These “recurring slope lineae”, or RSLs, were discovered a few years back, and they form on steep slopes every spring in a few places on Mars. There’s been a big debate over whether these things are formed by flowing water (which would be big news: flowing water on Mars today, right now, where we can witness and study it, not just billions of years ago in the distant past – these RSLs could be an environment where life could exist) or whether they’re just boring dry flows of sand or dust that only turn dark because for some weird reason the bright dust gets kicked off the surface (things like that also happen on Mars in other places).

But now they’ve found hydrated salts, which only form in the presence of water. So that means these RSLs are associated with water. They’re not just dry sandy avalanches. So now they’re places we need to pay more attention to, partly because we might find life there (yay!) and also because we need to be careful not to kill it or infect it with our biological cooties (boo!).

So in honor of this new discovery, I’m giving you a list of some of the words we’ve used to describe landforms on Mars. It’s true, we planetary scientists have a penchant for acronyms and names that don’t roll off the tongue. It may be partly because we lack imagination, but it’s also partly to cover ourselves (CYA, there’s another 3 letter acronym), so that we don’t pick a name that makes us assume something about what process forms that feature. Thus we have the mighty “recurring slope lineae” instead of something more catchy like “springtime slush”, because what if that name stuck and they turned out to be something much less exciting? Then we’d have to call them by the wrong name, and it would be the Pluto demotion fiasco all over again. Nobody wants that.

With some luck these RSLs will be renamed something more catchy. Most likely the IAU (another acronym!) will give them names relating to water features on Earth, like naming them after famous springs or fountains or something. That won’t happen for years to come. In the meantime, you can make your very own 3 letter acronym from the list above and play at martian geology. Have fun!

A wind-levelled surface

ESP_041864_1745_0.71x A Piece of Mars: In this 676×380 m (0.42×0.24 mi) scene, the high-standing hills here were all carved by sandblasting, by a wind that probably blew from right to left. Ripples in the valleys show that this erosion is still occurring today. (HiRISE ESP_041864_1745, NASA/JPL/Uni. of Arizona)

What do we know about planet formation?

Understanding how planets form in the Universe is one of the main motivations for GPI. Thanks to its advanced design, GPI specializes in finding and studying giant planets that are similar to Jupiter in our solar system. These are the kind of planets whose origin we hope to understand much better after our survey is complete.


This artist’s impression shows the formation of a gas giant planet around a young star. Credit: ESO/L. Calçada


Sand sheets and ripples

ESP_041977_1515_1.0xA piece of Mars: Not all sand piles up into big dunes. If the grains are the wrong grain size (too fine or too coarse), then it might just form sand sheets with ripples on top, like it does here, slowly migrating from top left to bottom right. There are two different kinds of sand here: the ripples seem more grayish and the underlying sand sheet seems more brownish. Grains of different sizes and densities respond to the wind in varying ways, so that they form different features on the surface. (HiRISE ESP_041977_1515, NASA/JPL/Univ. of Arizona)

The Slumbering Dwarf Awakens: Pluto is about to come back into the limelight


The best images so far of Nix and Hydra. Much better images will be sent down from the New Horizons spacecraft in early September

After the busiest July of our lives, the New Horizons team members have finally caught up on sleep. A few of us have even had a chance to take vacations. It’s good that we’re rested up, because an onslaught of new data from Pluto is about to begin.

Right now, 95% of the data obtained during the July 14 flyby is still stored on the spacecraft. After a quiet August, new images will start flowing down to Earth again on Saturday, We will get a few images almost every day. Why just a few? Well, Pluto is very far away, and the New Horizons transmitter is not very powerful. The downlink data rate is 125 bytes per second. For those who are old enough to remember dialup modems, this is slow even by that standard. It takes more than an hour for a single image to come down from the spacecraft. It will take almost a year before we have seen every image. That seems like a long time, but compared to the decade it took to plan, build and launch the spacecraft, and the second decade that it took to travel three billion miles to Pluto, waiting another year doesn’t seem so bad.

I am particularly looking forward to seeing some of our first closeup images of Hydra and Nix, two of Pluto’s small outer moons. Expect them to have weirdly irregular shapes, pockmarked by craters. The small moons of Pluto a particularly odd bunch. Whereas most of the moons in the Solar System rotate in a simple way, keeping one face toward the central planet at all times, we believe that Pluto’s moons might be tumbling chaotically. In a few days, maybe we will finally know for sure. Stay tuned.

By the way, every Friday the latest New Horizons images will be released to the public here:

What Self-Luminous Planets are Like

The planets that we are familiar with in our own solar system have evolved, aged, and cooled, for over 4.5 billion years since the Sun and planets formed. What do planets look like at younger ages? Can we use the light that a planet emits to understand its past history?


Layered winds

ESP_041991_1714_0.741xA piece of Mars: On the left is high ground, covered with dunes (or maybe they’re ripples) running from upper left to lower right. On the right is low ground, covered in deeply eroded dunes (ripples?) running almost from left to right. They were probably created at two different times by winds that changed direction in the intervening time. The set on the right is probably much older. (HiRISE ESP_041991_1715, NASA/JPL/Univ. of Arizona)

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.

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.