Capturing the shadow of Saturn's moon Titan from right here on Earth

phys.org | 7/20/2018 | Staff
echolea (Posted by) Level 3
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Titan is Saturn's largest moon, and it is more like a planet than a moon in many respects.

It has a thick atmosphere as well as wind, rivers, lakes made of hydrocarbons such as methane, and a liquid water ocean. Understanding its atmosphere may help us in the search for life on other planets.

Excitement - July - Opportunity - Study - Titan

Hence the excitement this July when a rare opportunity was available to further study Titan, from right here on Earth. On July 18 at 11:05pm (WAST, Western Australian time) Titan passed in front of a faint star, as seen by observers across most of Australia.

This event, known as an occultation, lasted only a few minutes and about 2% of the star's light was blocked by Titan's atmosphere.

Effect - Telescopes - Camera - Data - Implications

The effect was so small it required large telescopes and a special camera to record it. But the data gathered should have profound implications for our understanding of an atmosphere on another world.

Scientists have developed a very clever technique to examine Titan's atmosphere using stellar occultations. As Titan enters and exits an occultation, the star's light would illuminate the atmosphere from behind, but be blocked by the moon itself.

Scientists - Subtle - Changes - Brightness - Star

Scientists then record subtle changes in brightness of the star over a few minutes, which represents a profile of the atmosphere's density with height.

This method was used to study Titan's atmosphere before, during a stellar occultation in 2003.

Cassini - Huygens - Lander - Titan - Surface

But in 2005, when Cassini's Huygens lander arrived at Titan and descended to its surface, the atmospheric profile measured from its instruments did not match that derived from the 2003 occultation. This fuelled the question of how variable is the state of Titan's atmosphere.

Since the Cassini mission ended in 2017, NASA's Karsten Schindler said there was keen interest in any new atmospheric observations from occultations: "Occultations remain the only means to study Titan's upper atmosphere and its...
(Excerpt) Read more at: phys.org
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