Today's Image

Saturn’s moon Titan occults star in new images

Posted by
Kelly Kizer Whitt
and
December 1, 2022
Round orangish ball (Titan) with small ringed circle to lower right (star).
The European Southern Observatory’s Very Large Telescope watched Saturn’s moon large Titan occult, or pass in front of, a star on November 29, 2022. In this image, Titan is the big world on the left. The star is on the right (the ring around it is a camera artifact, and the black dots are bad pixels). Image via ESO/ VLT/ Connor A. Nixon.

Titan occults a star

On November 29, 2022, Titan, Saturn’s large moon, passed in front of a distant background star in an event called an occultation by astronomers. The European Southern Observatory’s Very Large Telescope captured the event in images you can see on this page.

Titan is the only moon in our solar system with a dense atmosphere. And the astronomers said this occultation offered them a unique chance to study this distant moon, which is known to have clouds, rain, rivers, lakes and seas of liquid hydrocarbons (like methane and ethane).

The Very Large Telescopes, or VLT – using its SPHERE adaptive optics was able to image Titan despite its distance of more than 700 million miles (1.1 billion km) from Earth. Astronomers were able to achieve a .04 arcsecond resolution of Titan and the passing star (resolution, to astronomers, is an indication of how clearly we see an object).

From Earth, Titan appears about .8 arcseconds wide. That’s tiny, considering that one degree of sky is equal to your pinky finger held at arm’s length. And it takes 60 arcminutes to make up one degree, and 60 arcseconds to make up one arcminute.

In the VLT image, the rings around the star are diffraction artifacts, and the white and black dots are bad pixels.

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The progression of the occultation

Connor A. Nixon, a planetary scientist at NASA Goddard who researches planetary atmospheres and astrobiology (life in the universe), was one of those studying the occultation. Here are Nixon’s play-by-play images of the occultation, via Twitter.

Bottom line: Titan occulted (passed in front of) a distant background star on November 29, 2022. The European Southern Observatory’s Very Large Telescope captured amazing images of the event.

Posted 
December 1, 2022
 in 
Today's Image

Kelly Kizer Whitt

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About the Author:
Kelly Kizer Whitt - EarthSky’s roving nature reporter on YouTube - writes and edits some of the most fascinating stories at EarthSky.org. She's been writing about science, with a focus on astronomy, for decades. She began her career at Astronomy Magazine and made regular contributions to other outlets, including AstronomyToday and the Sierra Club. She has nine published books, including a children's picture book, Solar System Forecast, and a young adult dystopian novel, A Different Sky.

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