See Jupiter and its Galilean moons in November 2021

Observe Jupiter's Galilean moons as the gas giant drifts towards evening twilight.

Published: October 28, 2021 at 11:33 am
Get your own Space Pen when you subscribe to BBC Sky at Night Magazine today!

As Jupiter drifts closer towards the evening twilight, there is still time for a few interesting events regarding its four largest Galilean moons.


On 6 November there’s a great opportunity to see the outer Galilean moon Callisto transiting Jupiter’s disc.

The event conveniently begins as darkness falls at around 16:45 UT, Callisto moving off Jupiter’s disc at 21:20 UT.

Discover more stargazing events on our monthly Star Diary podcast or find out more about observing the planets in November 2021.

An image showing Jupiter with its moon Callisto passing in front as a black dot
A south-up view of Callisto in transit over Jupiter’s disc on 6 November at 19:00 UT. Credit: Pete Lawrence.

Transits of Callisto only occur when viewing relatively close to a Jovian equinox, as occurred in May of this year.

On 9 November, there’s another conveniently timed event visible as the sky is darkening. A telescope will show the large dark shadow of Ganymede as it crosses the atmosphere of Jupiter.

This event plays out until 18:36 UT. However, if you miss this transit, there’s another opportunity to see Ganymede’s huge shadow in transit on 16 November.

This particular event starts under dark-sky conditions, beginning at 19:08 UT and concluding at 22:36 UT.

For those without the aid of a telescope, there’s a wonderful conjunction of the first quarter Moon and mag. –2.3 Jupiter on the evening of 11 November.

At 21:45 UT, as the pair approach the southwest horizon prior to setting, they will be around 5˚ apart – that’s about 10 apparent Moon diameters.


This guide originally appeared in the November 2021 issue of BBC Sky at Night Magazine.


Pete Lawrence, astronomer and BBC The Sky at Night presenter.
Pete LawrenceAstronomer and presenter

Pete Lawrence is an experienced astronomer and astrophotographer, and a presenter on BBC's The Sky at Night.

Sponsored content