This Week's Night Sky: Jupiter’s Moons in a Double Eclipse

A backyard telescope will reveal the shadows of Io and Ganymede merge on the surface of the gas giant.

The moon acts as a guide to stunning celestial sights throughout the week, and Jupiter’s largest moons converge in a special eclipse.

The first-quarter moon pins down the grouping, with the planet Jupiter appearing to the lower right and Venus closest to the horizon. After darkness falls completely, Regulus, the brightest star in the constellation Leo, joins the party between the moon and Jupiter. The Gemini twins Pollux and Castor, perched above Venus, complete this not-to-be-missed  cosmic get-together.

Starting at 8:58 p.m. EDT, icy Ganymede’s shadow makes its first appearance on Jupiter’s disk. The shadow of the volcanic moon Io begins its own transit at 10:01 p.m. EDT.

What makes this Jovian eclipse even more special is that both black dot-like shadows will

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