Institute of Astronomy

Astronomy News

NASA's Hubble Observations Suggest Underground Ocean on Jupiter's Largest Moon

4 January 2017 - 9:09am

Nearly 500 million miles from the Sun lies a moon orbiting Jupiter that is slightly larger than the planet Mercury and may contain more water than all of Earth's oceans. Temperatures are so cold, though, that water on the surface freezes as hard as rock and the ocean lies roughly 100 miles below the crust. Nevertheless, where there is water there could be life as we know it. Identifying liquid water on other worlds — big or small — is crucial in the search for habitable planets beyond Earth. Though the presence of an ocean on Ganymede has been long predicted based on theoretical models, NASA's Hubble Space Telescope found the best evidence for it. Hubble was used to watch aurorae glowing above the moon's icy surface. The aurorae are tied to the moon's magnetic field, which descends right down to the core of Ganymede. A saline ocean would influence the dynamics of the magnetic field as it interacts with Jupiter's own immense magnetic field, which engulfs Ganymede. Because telescopes can't look inside planets or moons, tracing the magnetic field through aurorae is a unique way to probe the interior of another world.

Join Hubble astronomers during a live Hubble Hangout discussion about Ganymede at 3pm EDT on Thurs., March 12, to learn even more. Visit .

New Year's Fireworks from a Shattered Comet

3 January 2017 - 9:07am
Video Length: 4:07

Earth will pass through a stream of debris from comet 2003 EH1 on January 3, 2017, producing a shower of meteors known as the Quadrantids.

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Window to hell: Io’s strongest volcano changes face as we watch

30 December 2016 - 12:05pm

The innermost moon of Jupiter is in an almost constant state of eruption - and its most persistent volcano, Loki Patera, keeps an unsteady rhythm

Vera Rubin, pioneering astronomer, dies at 88

30 December 2016 - 12:03pm

Astronomer Vera Rubin, whose pioneering work led to the theory of dark matter, dies at 88.