Astronomy facts
One short astronomy fact per day, each with a figure and a source. Pick a topic or scroll back through the days.
October 2026
- Oct 8 PlanetsSaturn Is Less Dense Than Water
- Oct 7 SunThe Sun Holds 99.8% of Solar System Mass
- Oct 6 PlanetsFirst Exoplanet Around a Sun-Like Star Found
- Oct 5 MoonThe Moon Has Shrunk About 50 Meters
May 2025
- May 17 PlanetsEarth and Venus Are Closer Than Any Other Planets
- May 16 PlanetsNeptune Is So Far That Sunlight Takes Over 4 Hours to Reach It
- May 15 SunThe Sun Could Fit Over a Million Earths Inside It
- May 14 PlanetsEarth Would Fit Inside Jupiter’s Great Red Spot
- May 13 Space HistoryThe Moon Has Artificial Satellites Orbitting it
- May 12 Space HistoryThe Oldest Satellite Still in Orbit Launched in 1958
- May 11 AstronautsAstronauts Can’t Cry Properly in Space
- May 10 AstronautsSpace Changes an Astronaut’s Height
- May 9 PlanetsSuper-Earths Might Be the Best Places for Life
- May 8 Dwarf Planets & Small BodiesSome Asteroids Are Just Piles of Rubble
- May 7 Night SkyThe Southern Cross Was Once Visible from Britain
- May 6 Night SkyOrion’s Belt Points to Other Famous Stars
- May 5 PlanetsTriton Orbits Neptune the “Wrong” Way
- May 4 PlanetsTitan Has Lakes of Liquid Methane
- May 3 PlanetsJupiter Has the Most Powerful Auroras in the Solar System
- May 2 PlanetsJupiter’s Moon Ganymede Has Its Own Magnetic Field
- May 1 The UniverseYou’re Made of Stardust—Literally
April 2025
- Apr 29 The UniverseAbsolute Zero Is Unreachable
- Apr 28 SunThe Sun Has an 11-Year Mood Cycle
- Apr 27 StarsBetelgeuse Might Explode Anytime (But “Anytime” Could Mean 100,000 Years)
- Apr 26 PlanetsMars Has Blue Sunsets
- Apr 25 Dwarf Planets & Small BodiesPlanet Nine Might Be a Captured Rogue Planet
- Apr 24 Dwarf Planets & Small BodiesSome Asteroids in the Belt Have Moons
- Apr 23 Dwarf Planets & Small BodiesThe Oort Cloud Is So Distant, We’ve Never Seen It Directly
- Apr 22 Dwarf Planets & Small BodiesThe Asteroid Belt Isn’t Packed with Rocks Like in Movies
- Apr 21 Dwarf Planets & Small BodiesThe Largest Meteorite Ever Found Weighs More Than an Elephant
- Apr 20 Dwarf Planets & Small BodiesSome Meteorites Contain Ingredients for Life