Saturn’s North Pole

north-poleThese two natural color images taken by the Cassini spacecraft show how Saturn’s north polar region has changed between 2012 and 2016. The color change is thought to be an effect of Saturn’s seasons. It suggested that the change from a bluish color to a more golden hue is due to the increased production of smog in the atmosphere as the north pole approaches summer solstice in May, 2017.

The hexagon, Saturn’s six-sided jetstream, may act as a barrier preventing haze particles produced outside it from entering. If that’s the case, the polar atmosphere could have become clear of aerosols produced by photochemical reactions, reactions caused by sunlight, during the winter. After Saturn’s equinox in August, 2009, the north pole polar has been in continuous sunshine, and smog aerosols are being produced inside the hexagon, making the polar atmosphere appear hazy.

Image Credit: NASA

The Red Spider Nebula

The Red Spider Nebula: Surfing in Sagittarius - not for the fainThe Red Spider Nebula, located some 3,000 light-years away in the constellation of Sagittarius, is a warm planetary nebula that contains one of the hottest stars known. The star’s powerful stellar winds generate 100 billion km high shock waves that sculpt the twin-lobed nebula. The waves are caused by supersonic shocks formed when the local gas is compressed and heated in front of the rapidly expanding lobes. The atoms caught in the shock emit the radiation seen in this image.

Image Credit: ESA

Clouds on Mars

Images from MAVEN’s Imaging UltraViolet Spectrograph were used to make this movie of rapid cloud formation on Mars. The ultraviolet light reflected from the planet has been rendered in false color to show what might be seen with ultraviolet-sensitive eyes. The movie uses four MAVEN images to show about 7 hours of Mars rotation, and it interleaves simulated views that could have been seen between the four images. The length of the Martian day is similar to Earth’s, so the movie shows just over a quarter day. The left part of the planet is in morning and the right side in afternoon. Mars’ prominent volcanoes, topped with white clouds, can be seen moving across the disk.  Olympus Mons, the tallest in the Solar System, appears as a prominent dark region near the top with a small white cloud at the summit that grows during the day. Olympus Mons appears dark because the volcano rises up above much of the hazy atmosphere. Three more volcanoes appear in a diagonal row with their cloud cover merging to span a thousand miles by the end of the “day.”

Video Credit: NASA