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A Piece of Mars: It’s all about wind scour here in this 0.75×0.75 km (0.47×0.47 mi) view. The big “swoop” is an erosional channel dug into the surface by winds (blowing from the lower left) trying to erode the hills in the center. But notice that the hills are all aligned to the upper left/lower right, like a school of fish swimming the same way). That alignment tells us there’s a second wind that came along later, blowing (I think) from the lower right. That wind also left behind some ripples (TARs, really) that swirled around the older big “swoop” channel. (HiRISE ESP_016372_1975, NASA/JPL, Univ. of Arizona)

Sidewalk Astronomy at Pier 17 in San Francisco on October 24 2017

See the universe from Pier 17 in San Francisco with Unistellar eVscope! SETI Institute astronomer Franck Marchis will be there to demo the prototype.

Join us on Tuesday, October 24, 2017, starting at 7:30 pm at Pier 17 (the building adjacent to Pier 15 the Exploratorium). We will share views through our evScope and other telescopes of nebulae, galaxies, star clusters, double stars, and other objects visible in the night sky (weather permitted of course).

(c) Thierry Cohen

(c) Thierry Cohen

Check our Facebook  and Twitter social media pages for regular updates during the evening. (more…)

Wavy dunes and straight dunes

A Piece of Mars: The dunes here are ~40 m (131 ft) apart and ~200 m (219 yd) long. (They’re not really dunes, but rather a windblown thing nearly unique to Mars that we call TARs.) Look carefully and you’ll see that some have very straight crests, like a sword – this is typical for TARs. But others have wavy crestlines, like huge serrated knives.

Why are some wavy while others are straight? My guess is that the straight-crested TARs formed first. TARs are known for being immobile. The wind forms them, and then they just stop moving, unlike dunes and ripples, which can migrate long distances. At some point after they formed, the wind direction shifted, maybe as the climate in this region changed. The TARs had become somewhat resistant to erosion by that point. They weren’t as hard as rocks, but they’d probably developed a crust that made it hard for this new wind to rework their sediment.

But the wind, like water, is relentless, and it worried away at the TARs. Eventually the crust on some of them gave way, maybe because it was less protected by local topography, or maybe because it just didn’t develop as strongly as those on neighboring TARs, or maybe because the new wind blew more sediment over some TARs and less over others. And so some of the TARs were partly reworked by this new wind, forming tiny little new TARs on the left sides of the older TARs, which led to the wavy crestlines. So today we see the history of two different winds, recorded in the waviness of TAR crestlines. (HiRISE ESP_051995_1525, NASA/JPL/Univ. of Arizona)

Saying Hello to Pluto from San Francisco with the eVscope

Observing Report #2 – September 25, 2017

A few days ago we announced the direct imaging of Pluto through the eyepiece of a Unistellar eVscope prototype located in Marseille, France. To make sure that this was not a fluke, I decided to try to observe Pluto from San Francisco— more precisely, from my little backyard in the middle of the city. And we succeeded!

Animation showing two observations of the same area of the sky taken with Unisteller’s eVscope. The dwarf planet Pluto (cyan circles) is moving with respect to the stars. The green circle shows the location of a cosmic ray that hit the detector during the recording of one frame.

Animation showing two observations of the same area of the sky taken with Unisteller’s eVscope. The dwarf planet Pluto (cyan circles) is moving with respect to the stars. The green circle shows the location of a cosmic ray that hit the detector during the recording of one frame.


The crazy laciness of martian TARs

A Piece of Mars: Take a look at the windblown stuff in this 0.55×0.625 km (0.34×0.39 mi) scene. Those are intricate patterns of a sort of dune-ripple thing that forms all over on Mars, but not so much on Earth. We call them TARs (transverse aeolian ridges, here are some other examples) because we’re still not sure what they are: dunes or ripples or something else? They’re beautiful, they reflect wind patterns in ways we don’t yet understand, and they might make up a large part of the martian sedimentary rock record. Be glad it’s not your job to try to tease all that out, these things are complex. (HiRISE ESP_051129_1705, NASA/JPL/Univ. of Arizona)

Das Start-up Unistellar greift nach den Sternen

Unistellar hat das Design seines neuen Enhanced Vision Telescope (eVscope™) auf der IFA Next in Berlin mit großem Erfolg vorgestellt – Start der Crowdfunding-Kampagne im Oktober
Das Teleskop ermöglicht Amateur-Astronomen dank seiner Technologie zur Lichtverstärkung einen einzigartigen Blick auf die Himmelsobjekte. Durch ein Crowdsourcing-Projekt sind nun „citizen scientists“ aufgerufen, die wissenschaftliche Forschung zu unterstützen.

Bildunterschrift: Laurent Marfisi, CEO von Unistellar präsentiert auf der IFA 2017 sein Teleskop – Video (Bildquelle: Business France)


Good-bye Cassini

04bI was at Caltech in California on September 15 2017, with 1500 other people, colleagues, friends and their families, to witness the «end-of-mission» event for Cassini.

Early in the morning, at 2 am, I got up and drove to the site, the mood was of sober festivity, you might have thought we were gathering for a late night summer open air movie. Stands were handing out memorials and snacks. People were tapping others in the back, smiling,watching the big screen with friendly faces pouring out information and feelings.

Later hugs would start, after the signal got smaller and then stopped completely on the screen, hugs would be necessary to hide the tears, half of them tears of happiness that we had accomplished such a wonderful mission, the rest tears of unavoidable chagrin : after a valiant fight against Saturn’s atmosphere, Cassini’s heart stopped, and we lost a star in the sky, someone who communicated with us for more than 20 years since the launch in October 1997.


A video of the last minutes of the mission as seen from Caltech


Dust trapped on the lee side

A Piece of Mars: This 0.95×1 km (.59x.62 mi) scene shows the center of a small dune field. The dunes are shaped by three winds blowing from three different directions: from the west-southwest, east, and south. The north-facing slopes are slip faces made by the south wind, and most of them have bright patches on them that are probably accumulations of airfall dust. Whatever winds brought the dust, none have yet been able to remove it. I’d bet that one of the most recent winds to pick up sand on these dunes blew from the south, because those bright dust patches are still visible on those north-facing slopes, where they’d be protected from southerly winds. (HiRISE ESP_049481_1310, NASA/JPL/Univ. of Arizona).

Seeing Pluto With Your Own Eyes From Your Backyard With Unistellar’s eVscope

One of the biggest challenges in popular astronomy is finding specific objects in the night sky. Most nebulae, galaxies, and asteroids are invisible to the naked eye, and locating them in the immense vastness of space has frustrated people for centuries.

Picture taken with a cellphone in the eyepiece of the telescope. The green circle labels the position of Pluto, which is visible.

Picture taken with a cellphone in the eyepiece of the telescope. The green circle labels the position of Pluto, which is visible.

That’s why most amateur astronomers follow a common but frustrating path. They buy a telescope, look at the moon, a few bright stars, and five planets—and then just give up. After only a few months of use, those telescopes go up for sale on eBay or into the basement.

Unistellar is determined to change this. Our new eVscope’s Autonomous Field Detection (AFD) feature will allow novice astronomers to find noteworthy celestial objects without performing complicated alignment procedures. Thanks to AFD’s intelligent pointing and tracking, astronomers can spend more time observing and less time wondering what they’re looking at. You’ll always know exactly what you’re seeing. (more…)

Starfest in Central Park: Urban Astronomy for All

Last week I traveled from San Francisco to New York City to attend Autumn Starfest, which is sponsored by the Amateur Astronomers Association (AAA) of New York. This star party’s most amazing feature is its location—right in the middle of Manhattan, in the magnificent Central Park! And after flying 2,600 miles (4,100 km), I was eager to show attendees that the Unistellar eVscope will let them see faint targets in the night sky—even the sky of this immense city, with all of its light and other forms of pollution.

And the great news is that the event, and our telescope, were a huge success.


The setup of Starfest in Central Park. It was obviously not a perfect dark sky for astronomy, but a beautiful summer evening for the public (credits: Ed Rojas,