How to Identify Jupiter's Moons

If you have a telescope or binoculars that let you see Jupiter's moons, then the Jupiter's Moons JavaScript Utility from Sky & Telescope will help. It allows you to identify the four brightest moons at any given time. Adjust the time using your UT offset to determine the local time. The tool automatically retrieves the UT offset from your computer, but you may want to verify that it is correct.

You can confirm for yourself that the moons are constantly changing position. Click on one of the buttons repeatedly, e.g., "+1 hour," to simulate this.