Jupiter’s moon was found to have a liquid ocean under a thick crust of ice.
The Galileo probe made the discovery.
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British astronomer William Lassell discovered Neptune's largest moon, Triton.
NASA revealed that water vapor was discovered in the atmosphere of an Earth-size planet, the exoplanet K2-18b.
Scientists discovered the most distant supermassive black hole.
The last total solar eclipse of the 20th century occurred and was visible from Europe and Asia.
Astronomer William Herschel first observed Uranus.
