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  • Writer's pictureStephen Strum

Eclipse on Jupiter: Io Shadow Transit

Updated: Jan 31, 2021

Animation of the shadow of Io tracking across Jupiter.
Animation of Io's shadow tracking across Jupiter.

On the evening of July 27, 2019 I was able to capture a shadow transit on Jupiter, which is shown in the animated gif above. One of Jupiter's four major moons, Io, passed in front of Jupiter, casting a distinct shadow on Jupiter as it did so. If you were flying above the cloud tops on Jupiter in the region the shadow passed you would essentially see a solar eclipse take place, albeit a very short one given how quickly Io revolves around Jupiter. The animation above shows the movement of Io's shadow and the rotation of Jupiter over just a two-hour period.

Shadow transits on Jupiter are very common, and two or even three shadow transits can occur at the same time depending on the orientation of Jupiter's moons. However, while many shadow transits are seen during the course of a given month, they are all short-lived and so frequently missed when looking at Jupiter through a telescope. You can use apps on your phone to find out when shadow transits will occur, as well as when the Great Red Spot will be visible, a great one being SkySafari Pro. A number of websites also have that information including:

You can watch a video of this shadow transit, along with raw imagery of Jupiter, Saturn and some composite images below. Links to the astronomy equipment and software I used to produce this animation are at the end of the post.

Astronomy Software:

◆ Topaz Labs DeNoise:

My astronomy gear:

◆ Celestron C6:

◆ C6 from Highpoint Scientific:

◆ ES Twilight I Mount:

◆ From Highpoint Scientific:

◆ Skywatcher AZ-GTi Mount:

◆ 2x thread on Barlow lenses:

◆ Canon camera adapter:

◆ William Optics Binoviewer:

◆ Vixen Zoom:

◆ Televue 19 panoptic:

◆ Televue 9mm Nagler:

◆ Televue 3.5mm Nagler:

(NOTE: Some of the above links are Amazon affiliate links: I make a small commission from any purchases made through those links.)

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