Saturn’s moon Titan will occult a star on July 9

Titan will occult: Chart showing Saturn with dots around it, two close together as Titan occults a star.
View labeled version. | Aim your telescope toward Saturn and its largest moon, Titan, early Saturday morning for a rare treat. Titan will occult a star of similar brightness to itself on the morning of July 9, 2022. The star is HIP 107569. A large portion of North America, Central America and part of South America can see it happen. This chart shows two dots at far left – Titan (orangish) and the star – just before the occultation begins. Image via Stellarium.

Titan will occult a star

The largest and brightest moon of Saturn, Titan, will occult – or pass in front of – a background star on July 9, 2022. The event will start around 09:14 UTC or a few minutes after depending on your location. Titan shines at magnitude 8.5, bright enough for you to view it through even small backyard telescopes. The star it will occult is similar in brightness at magnitude 8.7.

The occultation, when the background star winks out as it’s behind Titan, will last for a maximum of 5 1/2 minutes depending on how close you are to the centerline. Here’s an interactive Google map to help you find out if you can see the occultation from your location. This list of cities will give you the time of disappearance and reappearance of the occulted star in the right-hand columns. The times are listed in Universal Time (UTC). Learn how to convert UTC to your time.

The background star does not have a proper name but goes by a couple catalog numbers, including HIP 107569 and HD 207123. The star, in the constellation Capricornus, lies 834 light-years away and is similar in temperature to our sun.

What will it look like?

So, you’re out under the dark morning sky with your telescope. You’ve spotted Saturn, and two dots near to each other in the same field of view. What happens next? David and Joan Dunham of the International Occultation Timing Association said:

When Titan gets close enough to the star that the two appear to merge, they will appear as a single object of magnitude 7.9. Then, for several seconds, the object will gradually diminish in brightness as the star sinks into Titan’s atmosphere, eventually reaching the magnitude 8.5 of Titan as the star completely disappears.

For those located close to the centerline, which runs from Mexico to the Bahamas, you get a bonus. You’ll have a chance to see a flash as Titan’s atmosphere bends and focuses the light of the background star. As the IOTA release says:

Of special interest will be the central flash that will occur close to the occultation’s central line, when Titan’s entire atmosphere will focus the star’s light, causing it to brighten briefly well above its un-occulted level at central occultation.

Map of Pacific and parts of Western Hemisphere with three parallel curving lines.
If you are within the purple lines, you can see the Titan occultation of a background star. For those close to the centerline (black), you may also witness a flash. Image via IOTA.

Don’t forget about the planetary lineup!

As long as you’re up early in the morning and gazing at the sky, remember to check out the lineup of planets. Can you still see Mercury? Maybe not. It’ll be close to the sun. But Venus, Mars, Jupiter and Saturn still form a graceful arc across the sky before sunup. Their line across the sky follows the sun’s path and shows you the plane of our solar system, aka the ecliptic.

Bottom line: Titan occults a background star on the morning of July 9, 2022. You can see Titan, the largest moon of Saturn, with a small telescope.


July 5, 2022

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Kelly Kizer Whitt

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