Tag Archives: UV

Looking at Mars at Night in UV

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This obviously false color animation of Mars shows how its atmosphere glows and pulsates in ultraviolet light every night. It was assembled from months of data taken by the MAVEN spacecraft orbiting Mars. The nightglows occur three times during each rotation of the planet about 70 km above the surface. All three occur at sunset (which is on the left limb of the planet in this view). The pulsations are believed to be caused by downward winds creating nitric oxide in the atmosphere which glows in the UV spectrum. The fact that the three glows occur in data averaged over several months indicates that they are a nightly occurrence.

Video Credit: NASA

Clouds on Mars

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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

B and C in UV

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RingsInUVOn 1 July, 2004, the Cassini spacecraft arrived at Saturn, marking the end of the spacecraft’s nearly seven-year journey through the solar system and the beginning of its tour of Saturn and the planet’s rings and moons.

This picture was taken in ultraviolet on 30 June, 2004 during Cassini’s orbital insertion maneuver. It shows, from left to right, the outer portion of the C ring and inner portion of the B ring which begins a little more than halfway across the image. The “dirty” particles are indicated by red, and “cleaner: ice particles shown in turquoise.

Saturn’s ring system is labeled from the inside out with the D, C, B and A rings followed by the F, G and E rings.

Image Credit: NASA

Sunspot Loops in UV

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sunspotloops_traceFrom time to time, it is the pleasure of Hogeman, Internet Astronomer, to feature amazing views of the Sun as seen in ultraviolet light by the Solar Dynamics Observatory satellite operated by NASA. Today’s picture comes from the earlier TRACE mission and was taken in 2000 during the last solar cycle. It shows a quiet day on the Sun, but, even on slow days, the Sun’s surface is a busy place. The relatively cool dark regions have temperatures of thousands of degrees Celsius. A large sunspot group called AR 9169 can be seen as the bright area near the horizon. The bright glowing gas flowing around the sunspots has a temperature of over one million degrees Celsius. We’re not sure of the reason for the high temperatures, but the best guess is that it’s related to the rapidly changing magnetic field loops that channel solar plasma. Large sunspot group AR 9169 moved across the Sun during the autumn of 2000 and decayed within a few weeks.

Image Credit: NASA

Saturn in UV

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Saturn in UV

In 2009, astronomers using the Hubble Space Telescope took advantage of a rare opportunity to record Saturn when its rings were edge-on to the Earth allowing a simultaneous view of both of the giant planet’s poles. It takes Saturn about 29-1/2 years to orbit the Sun; the opportunity to see the aurorae at both of its poles together occurs only twice during that time.

The aurorae are produced when electrically charged particles race along the planet’s magnetic field and strike the upper atmosphere where they excite atmospheric gases, causing them to glow. Saturn’s aurorae resemble those that take place at the Earth’s poles.

Image Credit: NASA