Astronomy facts
One short astronomy fact per day, each with a figure and a source. Pick a topic or scroll back through the days.
March 2025
- Mar 17 The UniverseThe Speed of Light Isn’t Always the Speed of Light
- Mar 16 PlanetsVenus Has Metal Snow
- Mar 15 PlanetsSome Planets May Be Made of Crystallized Carbon and Oxygen
- Mar 14 PlanetsVenus Has the Hottest Surface in the Solar System
- Mar 13 Black HolesSome Black Holes Grew Huge Within a Billion Years
- Mar 12 PlanetsThere’s a Giant Hexagon on Saturn’s North Pole
- Mar 11 MoonMoon Footprints Will Last Tens of Thousands of Years
- Mar 10 StarsThe Fastest Known Spinning Star Is a Dead One
- Mar 9 PlanetsA Planet Once Thought to Be Made of Diamond
- Mar 8 GalaxiesThe Milky Way May Collide with Andromeda
- Mar 7 StarsThere’s a Star That Pulses Like a Beating Heart
- Mar 6 PlanetsSome Planets Are Roaming the Galaxy Alone
- Mar 5 PlanetsA Day on Mercury is Longer Than Its Year
- Mar 4 The UniverseThere’s a Giant Void in Space with Almost Nothing in It
- Mar 3 PlanetsSaturn’s Moon Titan Has Rivers and Lakes—But They’re Not Water
- Mar 3 PlanetsJupiter’s Moon Io is the Most Volcanic World in the Solar System
- Mar 2 Black HolesSome Black Holes Shoot Out Jets Bigger Than Galaxies
- Mar 2 MoonEarth Might Have Had Two Moons at Some Point
- Mar 1 Dwarf Planets & Small BodiesEarth Has a Quasi-Moon Called Cruithne
- Mar 1 SunThe Sun’s Atmosphere is Hotter Than Its Surface
February 2025
- Feb 28 StarsThere’s a White Dwarf Racing at 2,800 km/s
- Feb 27 GalaxiesOne Galaxy is Made Almost Entirely of Dark Matter
- Feb 26 StarsNeutron Stars Are So Dense They Warp Light
- Feb 25 The UniverseSpace is Closer Than You Think
- Feb 24 MoonThe Moon is Moving Away from Earth
- Feb 23 PlanetsThe Largest Volcano in the Solar System is on Mars
- Feb 22 PlanetsThere’s a Planet Where It Rains Glass Sideways
- Feb 21 Black HolesA Star Once Vanished Without Exploding
- Feb 21 PlanetsVenus Spins the Wrong Way
- Feb 20 The UniverseThe Universe Has a Cold Spot No One Can Explain
- Feb 19 MoonSome Moons Have Moons