Astronomy facts
One short astronomy fact per day, each with a figure and a source. Pick a topic or scroll back through the days.
April 2025
- Apr 9 SunThe Sun’s Core May Spin Faster Than Its Outer Layers
- Apr 8 The UniverseAn Unexplained Radio Source Bursts Toward the Galactic Center
- Apr 7 PlanetsA Day on Mercury Has Two Sunrises
- Apr 6 MoonA Mirror on the Moon Helps Us Measure Its Distance
- Apr 5 Missions & SpacecraftThe Fastest Thing Ever Made by Humans Is a Space Probe
- Apr 4 PlanetsThe First Exoplanet Was Discovered Around a Dead Star
- Apr 3 MoonThe Moon Rings Like a Bell
- Apr 2 Night SkyThe Best Time to Stargaze Isn’t Always at Midnight
- Apr 2 PlanetsThe Great Red Spot Is Shrinking
- Apr 1 The UniverseThe Universe Is Missing Most of Its Matter
March 2025
- Mar 28 StarsA Single Spoonful of Neutron Star Material Weighs as Much as a Mountain
- Mar 27 SunThe Sun Will One Day Swallow Earth (But Not for a While)
- Mar 26 StarsA Magnetar Once Blasted Earth with a Gamma-Ray Flare
- Mar 25 PlanetsThe Other Planets Nearly Fit Between Earth and the Moon
- Mar 24 The UniverseSpace Can Expand Faster Than Light
- Mar 23 MoonThe Dark Side of the Moon Isn’t Always Dark
- Mar 22 Dwarf Planets & Small BodiesPluto Has Ice Mountains as Tall as the Rockies
- Mar 21 PlanetsYou Weigh Less at the Equator Than at the Poles
- Mar 20 PlanetsJupiter Has the Deepest Ocean in the Solar System (But It’s Not Water)
- Mar 19 The UniverseNeutrinos Pass Through You by the Trillions
- Mar 18 AstronautsYou Could Survive 15 Seconds in Space (But You Shouldn’t Try)
- 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