Inside planets and stars
Composition, structure and internal dynamics of planets and stars.
37 problemsPlanetary science
The formation, interiors, and histories of planets and moons.
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Browse collectionsPlanets and rings
Planet formation, atmospheres, thermal histories, distant orbits and Saturn’s moons and rings.
15 problemsA few problems to explore
15 totalJupiter’s interior
Juno’s measurements suggest that Jupiter’s core blends gradually into its hydrogen-rich surroundings. How large is this region, what is it made of, and how did it form?
Venus’s climate history
Venus and Earth began as similar rocky planets. Did Venus ever have oceans, or did its water remain steam and escape before oceans could form?
Moon formation
A giant impact is the leading explanation for the Moon’s origin. Its exact sequence must account for the Moon’s composition, orbit and relationship to Earth.
Early Mars climate
Ancient Martian rocks and landforms record liquid water under a fainter Sun. What climate sustained it, and how persistent were those wet conditions?
Uranus’s internal heat
Uranus does release heat from its interior, despite older claims that it does not. How does its interior lose heat and produce the seasonal energy budget we observe?
Planetesimal formation
Planetary systems start with small solid grains. How do these become gravitationally bound bodies before collisions or inward drift remove them?