Jupiter’s moons and the Great Red Spot
The four large moons, their shadows on the cloud tops and the Great Red Spot as they look in a small telescope, at any moment. Below are this week’s moon events and spot transits, marked by whether Jupiter is up in a dark sky where you are.
Drag sideways to move through time, scroll or pinch to zoom, tap a moon to pick it out.
- : in Jupiter’s shadow (eclipse)
- : west of Jupiter
- : east of Jupiter · its shadow is on Jupiter
- : in Jupiter’s shadow (eclipse)
Moon events this week
Transits, shadow transits, eclipses and occultations of the four large moons in the next seven days that you can see from New York: Jupiter up and the sky dark.
| Date | Time | Event | Jupiter from New York |
|---|
Transit and occultation times are when the centre of the moon crosses the edge of Jupiter’s disc as seen from Earth. Shadow-transit times are when the centre of its shadow does, and eclipse times are when the centre of the moon enters or leaves Jupiter’s shadow. They are calculated with Astronomy Engine’s model of the moons and can differ from other almanacs by a few minutes.
When the Great Red Spot faces Earth
The Great Red Spot turns with Jupiter, once every 9 hours 56 minutes. It is easiest to see when it crosses the middle of the disc (the central meridian). It is on the side facing Earth from the moment it comes round one edge until it leaves at the other.
| Date | Comes into view | Crosses the middle | Leaves view | Jupiter from New York |
|---|
The spot’s longitude: 95° (System II) on October 1, 2026, drifting about 1.6° a month, from the JUPOS team’s measurements. Each degree of difference moves these times by about 1.7 minutes. JUPOS
What the events mean
- Transit: the moon crosses in front of Jupiter. It is hard to see against the bright clouds.
- Shadow transit: the moon’s shadow falls on Jupiter as a small black dot, easy to see in a small telescope.
- Eclipse: the moon passes into Jupiter’s shadow and fades from view, although it is not behind the planet.
- Occultation: the moon passes behind Jupiter.
Binoculars and the naked eye show north up and east on the left. A Newtonian reflector turns the view upside down (south up). A refractor or Schmidt-Cassegrain with a star diagonal shows a mirror image (north up, east on the right).
Moon positions: Astronomy Engine. Central meridian and the pole’s direction: Jean Meeus, Astronomical Algorithms, chapter 43, as implemented by the astronomia library. Great Red Spot: JUPOS. Data sources
Frequently asked questions
What do I need to see the moons?
Jupiter’s four large moons show in steady binoculars. Titan, Saturn’s largest moon, shows in a small telescope.
Why is the view flipped compared with my telescope?
The view is drawn as the eye sees the sky, with east on the left. Many telescopes flip or mirror the image.
How accurate are the positions?
They come from Astronomy Engine’s model of the moons and are accurate to well within what a telescope shows.
Related guides
- Binoculars for stargazing: what to buy and what to look atA pair of 7x50 or 10x50 binoculars shows the craters of the Moon, the moons of Jupiter, dozens of star clusters and the Andromeda Galaxy, for a fraction of the cost of a telescope.
- How to find planets in the night skyFive planets are easy to see with the naked eye. Here is where to look, when, and how to recognise them.