Category
Planetary Science
Explore the 12 entries currently assigned to this category. These counts describe this curated catalogue, not the size or rate of change of the field itself.
At a glance
What this category contains
Explore the entries
Browse Planetary Science
Filter the category, choose how entries are grouped, and change the ordering without leaving the page.
Showing all 12 entries
Not a fact anymore
Long-lived dense planetary rings can survive only inside their parent body’s Roche limit.
What we know now
Quaoar, a small body orbiting beyond Neptune, has a dense ring far outside its classical Roche limit, the region where tidal forces can prevent loose ring material from assembling into a moon. The Roche limit is therefore not an absolute outer boundary for dense rings.
- Status
- Narrowed
- Category
- Planetary Science
- Accepted for
- Not quantified
- Changed approximately
- 2023
Not a fact anymore
Mars has a liquid metallic core with a radius of about 1,830 km.
What we know now
Mars appears to have a smaller metallic core than first estimated by NASA's InSight mission. Newer analyses place the liquid core at roughly 1,650–1,675 km in radius, with a layer of molten silicate rock above it.
- Status
- Corrected
- Category
- Planetary Science
- Accepted for
- ≈2 years
- Changed approximately
- 2023
Not a fact anymore
Mars became dry mainly because its ancient surface water escaped into space.
What we know now
Mars lost substantial water to space, but that was not its only major fate. Isotope-constrained models indicate that ocean-scale amounts of ancient water could also have become locked into hydrated minerals in the crust, while some remains in ice and other reservoirs.
- Status
- Narrowed
- Category
- Planetary Science
- Accepted for
- Not quantified
- Changed approximately
- 2021
Not a fact anymore
The Moon’s youngest mare volcanism required a KREEP-rich mantle source enriched in heat-producing elements.
What we know now
Chang’e-5 returned lunar basalts about 2 billion years old whose chemistry points to a mantle source with little KREEP contribution. KREEP—material rich in potassium, rare-earth elements, phosphorus, and heat-producing radioactive elements—is therefore not required as the direct source of the Moon’s youngest volcanism.
- Status
- Narrowed
- Category
- Planetary Science
- Accepted for
- Not quantified
- Changed approximately
- 2021
Not a fact anymore
Titan’s outward tidal migration should be extremely slow because it orbits far from Saturn.
What we know now
Titan is slowly moving away from Saturn, but much faster than older tidal models predicted for such a distant moon. Cassini measurements support a process called resonance locking, in which Titan can remain strongly coupled to changing oscillations inside Saturn and continue receiving tidal energy.
- Status
- Corrected
- Category
- Planetary Science
- Accepted for
- Not quantified
- Changed approximately
- 2020
Not a fact anymore
Pluto is a large planet, possibly comparable in size to Earth or Mercury.
What we know now
Pluto is much smaller than Mercury and smaller than Earth's Moon, with a diameter of about 2,377 kilometers.
- Status
- Corrected
- Category
- Planetary Science
- Accepted for
- ≈62 years
- Changed approximately
- 1978–2015
Not a fact anymore
Comets are simply loose dirty snowballs made mostly of volatile ice and dust.
What we know now
Comets contain ice and dust, but their nuclei can be dark, porous, layered, structurally complex, and rich in organics and minerals. Some are better described as icy dirtballs than dirty snowballs.
- Status
- Superseded
- Category
- Planetary Science
- Accepted for
- ≈31 years
- Changed approximately
- 1986–present
Not a fact anymore
Small moons are cold, geologically dead worlds.
What we know now
Some moons are highly geologically active. Io has intense volcanism; Europa and Enceladus contain subsurface oceans and show active ice deformation or plumes. Tidal heating from their planets can continually flex these moons and generate internal heat.
- Status
- Overturned
- Category
- Planetary Science
- Accepted for
- ≈19 years
- Changed approximately
- 1979–present
Not a fact anymore
Seasonal dark regions on Mars are vegetation responding to the Martian seasons.
What we know now
Mars has no confirmed surface vegetation. Seasonal and long-term albedo changes are produced mainly by dust movement, frost, winds, and exposed darker ground.
- Status
- Overturned
- Category
- Planetary Science
- Accepted for
- ≈80 years
- Changed approximately
- 1960s–1970s
Not a fact anymore
Venus probably has a mild, wet, Earth-like surface hidden beneath its clouds.
What we know now
Venus has a dry, hostile surface with temperatures around 465°C and pressures about 90 times Earth's sea-level pressure.
- Status
- Overturned
- Category
- Planetary Science
- Accepted for
- ≈77 years
- Changed approximately
- 1950s–1970s
Not a fact anymore
Most of the Moon's craters were formed by volcanic activity.
What we know now
Most lunar craters were excavated by impacts from asteroids and comets. Volcanism created the dark maria and other features, but it did not produce the Moon's dominant crater population.
- Status
- Overturned
- Category
- Planetary Science
- Accepted for
- ≈110 years
- Changed approximately
- 1950s–1970s
Not a fact anymore
The asteroid belt is the debris of a planet that exploded.
What we know now
Most asteroid-belt material is leftover planet-building material that never assembled into a full planet, largely because Jupiter's gravity disrupted accretion.
- Status
- Superseded
- Category
- Planetary Science
- Accepted for
- ≈101 years
- Changed approximately
- Mid-20th century–present
No entries match those filters.