While Jupiter is almost always a fine sight for stargazers, this weekend you’ll see the extra spectacle of two shadows moving across the face of the big planet late Saturday night or early Sunday morning. The two shadows will be cast by the moons Europa and Ganymede as they pass between Jupiter and the sun. Here’s how to see the event…
Finding Jupiter is easy enough. Look eastward and upward in mid-evening to find the brilliant planet… it’s the brightest object in the night sky except for the Moon.
While you can follow the continuous movements of Europa and Ganymede (along with Io and Callisto) with binoculars, you will need a telescope to see the moons’ two shadows during this event. Once you have Jupiter in your sights, start at a magnification of 75x or so, and move higher until you get the best image. It will depend on your telescope and seeing conditions. Steady sky helps.
The shadows will be tiny pinpricks of darkness, and it takes a little time to see them. Look carefully, and be patient. They will jump out at you.
Here’s a video of a single shadow from Io moving across Jupiter.
The two shadows will be visible between 1:40 and 3:04 UTC (Universal Coordinated Time), which is the same as GMT (Greenwich Mean Time). So that is, for example…
- October 24 from 2:40 a.m. to 4:04 a.m. British Standard Time
- October 24 from 3:40 a.m. to 5:04 am in South Africa Standard Time
- October 23 from 9:40 p.m. to 11:04 p.m. Eastern Daylight Time
- October 23 from 6:40 p.m. to 8:04 p.m. Pacific Daylight Time
This website helps you convert UTC for your own time zone:
In Australia, New Zealand, and Hawaii the event will occur during daylight on October 24, so you’re out of luck. But get out and see Jupiter anyway, because you’ll see the Great Red Spot moving past the center of Jupiter’s disk at 11:01 UTC on October 23, which is night for most of parts of the western Pacific. Again, the website above will help you convert to your local time.
A shadow on Jupiter is not a rare event, but two shadows is far less common. It’s well worth a look, and far better than watching bad T.V. Good luck and good viewing…