Polar Vortex


The polar vortex of Venus – south pole.

ESA has a nice video version located here.

Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Univ. Oxford

ESA’s caption:

This ghostly puff of smoke is actually a mass of swirling gas and cloud at Venus’ south pole, as seen by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard ESA’s Venus Express spacecraft.

Venus has a very choppy and fast-moving atmosphere – although wind speeds are sluggish at the surface, they reach dizzying speeds of around 400 km/h at the altitude of the cloud tops, some 70 km above the surface. At this altitude, Venus’ atmosphere spins round some 60 times faster than the planet itself. This is very rapid; even Earth’s fastest winds move at most about 30% of our planet’s rotation speed. Quick-moving Venusian winds can complete a full lap of the planet in just four Earth days.

Polar vortices form because heated air from equatorial latitudes rises and spirals towards the poles, carried by the fast winds. As the air converges on the pole and then sinks, it creates a vortex much like that found above the plughole of a bath. In 1979, the Pioneer Venus orbiter spotted a huge hourglass-shaped depression in the clouds, some 2000 km across, at the centre of the north polar vortex. However, other than brief glimpses from the Pioneer Venus and Mariner 10 missions in the 1970s, Venus’ south pole had not been seen in detail until ESA’s Venus Express first entered orbit in April 2006.

One of Venus Express’ first discoveries, made during its very first orbit, was confirming the existence of a huge atmospheric vortex circulation at the south pole with a shape matching the one glimpsed at the north pole.

This south polar vortex is a turbulent mix of warming and cooling gases, all surrounded by a ‘collar’ of cool air. Follow-up Venus Express observations in 2007, including this image, showed that the core of the vortex changes shape on a daily basis. Just four hours after this image the vortex looked very different and a day later it had morphed into a squashed shape unrecognisable from the eye-like structure here.

A video of the vortex, made from 10 images taken over a period of five hours, can be seen here. The vortex rotates with a period of around 44 hours.

The swirling region shown in this VIRTIS image is about 60 km above the planet’s surface. Venus’ south pole is located just up and to the left of the image centre, slightly above the wispy ‘eye’ itself.

This image was obtained on 7 April 2007 at a wavelength of 5.02 micrometres. It shows thermal-infrared emission from the cloud tops; brighter regions like the ‘eye’ of the vortex are at lower altitude and therefore hotter.


Curiosity’s Look at Mount Sharp


Click the image for a larger version.  In case you don’t read the press release below, this image is adjusted to “Earth light”, or how this would appear if it were on Earth.

The press release:

This view from the Mast Camera (Mastcam) on NASA’s Curiosity Mars rover shows a site with a network of prominent mineral veins below a cap rock ridge on lower Mount Sharp.

Researchers used the rover in March 2015 to examine the structure and composition of the crisscrossing veins at the “Garden City” site in the center of this scene. For geologists, the vein complex offers a three-dimensional exposure of mineralized fractures in a geological setting called the Pahrump section of the Lower Murray Formation. Curiosity spent several months examining sites in the Pahrump section below this site, before arriving at Garden City.

Mineral veins such as these form where fluids move through fractured rocks, depositing minerals in the fractures and affecting chemistry of the surrounding rock. In this case, the veins have been more resistant to erosion than the surrounding host rock.

The component images of this mosaic view were taken by the left-eye camera of Mastcam on March 27, 2015, during the 938th Martian day, or sol, of Curiosity’s work on Mars. The scene is presented with a color adjustment that approximates white balancing, to resemble how the rocks would appear under daytime lighting conditions on Earth.

For scale, the cap rock scarp is about 3 feet (1 meter) tall.

Polar Vortex


The Cassini spacecraft took this image of the polar vortex on Saturn’s moon Titan in 2012.

Now scientists have detected a monstrous new cloud of frozen compounds in the moon’s low- to mid-stratosphere – a stable atmospheric region above the troposphere, or active weather layer.

Read on for the Cassini press release:

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Pluto’s Twin Ice Volcanoes?

plutovolcanoThis is simply amazing!  Imagine, nitrogen lava.

Scientists using New Horizons images of Pluto’s surface to make 3-D topographic maps have discovered that two of Pluto’s mountains, informally named Wright Mons and Piccard Mons, could possibly be ice volcanoes. The color is shown to depict changes in elevation, with blue indicating lower terrain and brown showing higher elevation; green terrains are at intermediate heights.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Click here for more from New Horizons

Phobos Breaking Apart?


Credits: NASA/JPL-Caltech/University of Arizona

I’ve always wondered about the grooves on Phobos.   I always figured they were somehow related to a huge impact.  i never saw one this coming:

The long, shallow grooves lining the surface of Phobos are likely early signs of the structural failure that will ultimately destroy this moon of Mars.

Orbiting a mere 3,700 miles (6,000 kilometers) above the surface of Mars, Phobos is closer to its planet than any other moon in the solar system. Mars’ gravity is drawing in Phobos, the larger of its two moons, by about 6.6 feet (2 meters) every hundred years. Scientists expect the moon to be pulled apart in 30 to 50 million years.

We think that Phobos has already started to fail, and the first sign of this failure is the production of these grooves,” said Terry Hurford of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

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Pluto’s Merged Moons?


The more information that comes back from New Horizons the more intriguing the Pluto system become.

It now looks like at least two of Pluto’s moons came to be of mergers of smaller moons as shown in the red circles.   Again, WOW.

“We suspect from this that Pluto had more moons in the past, in the aftermath of the big impact that also created Charon”  — Mark Showalter (SETI Institute)


Pluto’s Spinning Moons


New Horizons / NASA – The New Horizons mission also is shedding new light on Pluto’s fascinating system of moons, and their unusual properties. For example, nearly every other moon in the solar system — including Earth’s moon — is in synchronous rotation, keeping one face toward the planet. This is not the case for Pluto’s small moons.

Pluto’s small lunar satellites are spinning much faster, with Hydra — its most distant moon — rotating an unprecedented 89 times during a single lap around the planet. Scientists believe these spin rates may be variable because Charon exerts a strong torque that prevents each small moon from settling down into synchronous rotation.

Another oddity of Pluto’s moons: scientists expected the satellites would wobble, but not to such a degree.