Planets
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PlanetsCatching a Comet’s Tail
A closeup visit by a NASA spacecraft helps show how a comet gets its shape.
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EarthKiller space rock snuffed out ancient life
Rock fragments from Antarctica suggest a huge meteor struck Earth 250 million years ago.
By Emily Sohn -
PlanetsA planet from the early universe
Astronomers have found the oldest and most distant planet known in the universe.
By Emily Sohn -
PlanetsMelting Snow on Mars
Melting blankets of snow may have carved out Martian gullies.
By Emily Sohn -
PlanetsA planet’s slim-fast plan
A planet orbiting very close to its sun can quickly lose weight.
By Emily Sohn