Titan occultation can give astronomers clues about Saturn’s largest moon

When Titan is directly between a star (the sun) and an observer (of the Cassini spacecraft in 2017), the hazy atmosphere it is easier to study.

(NASA/JPL-Caltech/Space Science Institute)

Astronomers in Australia are eager for a special galactic alignment this week that could tell them more about one of the most intriguing candidates to host life beyond Earth.

That is because it’s for a short 4 minutes late Wednesday night (July 18) local time, Saturn’s moon Titan will slip directly between the Earth and a star. The rare alignment, formally called an occultation, will let astronomers study light flows through the layers of Titan’s hazy atmosphere.

“It will be like an eclipse of the sun, with the moon in passing, but on a very subtle scale,” David Coward, an astronomer at the University of Western Australia, told The West Australian, a local newspaper. “This eclipse forms a track over the Earth, and if Titan goes in front of the star, the light in the atmosphere and allows scientists to use the data to work out the composition. The stars have to line up, literally.”

Scientists stuck on Earth observing occultations of Titan since 1989. They also used the Cassini spacecraft journey to Saturn to study the occultations of the moon to the mission at the end of September last year.

More Of

  • Saturn’s moon Titan

  • Cassini spacecraft


But because the composition of the moon’s atmosphere is changing over time, astronomers always want more observations. These changes may be caused by geological processes or, possibly, by some form of microbial life.

Scientists are not only the use of telescopes on the ground and they have a company in heaven. That is possible thanks to the Stratospheric Observatory for Infrared Astronomy, or SOFIA, an observatory that carries a telescope, a modified jet aircraft and is carried out by the NASA and the German space agency. Because SOFIA can fly, can collect data from the middle of the blurred shadow of Titan in front of the star, allowing the avoidance of a cloud cover that could interfere with observations.

The stars that are involved in the occultation goes by the catchy name of Gaia DR2 4090460400982698240. The occultation will take place some time after 11 pm, and on Wednesday, or a little after 11 pm local time in Perth, Australia.

Now, the weather forecast has scientists a little anxious about their chance at a bright sky for their ground based observations.

“There is much human drama in it,” Coward told the newspaper. “All of this would end in tears if it goes cloudy for these four minutes or when it rains.”

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