Astronomie
10 cards from across every topic, each citing a source. Tap one to open it in the feed.
- A teaspoon of this weighs more than a mountain range.
When a massive star explodes, its core can collapse into a neutron star: about 1.4 solar masses squeezed into a sphere …
- How astronomers measure star distances with a 300-million-kilometre ruler.
Hold a thumb up and blink each eye in turn: it jumps against the background. Stars do the same when Earth sits on the …
- On Mars, sunsets are blue.
By day the Martian sky is butterscotch, because iron-rich dust scatters the light. At sunset it flips: around the …
- On Uranus, polar night lasts 42 years.
Uranus rolls around the Sun almost on its side: its axis is tilted by about 98 degrees, versus 23 for Earth. One orbit …
- On Venus, a day lasts longer than a year.
Venus needs 225 Earth days to orbit the Sun but 243 Earth days for a single spin on its axis. It also rotates …
- Saturn would float in a bathtub, if the tub were big enough.
Saturn weighs 95 Earths but is so puffed up that its mean density is just 0.687 grams per cubic centimetre, about 30 …
- The Sun isn't yellow. It's white.
From space or high in the midday sky, the Sun shines white; its surface radiates at about 5,777 kelvin like a white-hot …
- The first black hole photo needed an Earth-sized telescope.
In 2019 the Event Horizon Telescope revealed the shadow of the black hole in galaxy M87, 55 million light-years away …
- The gold in your ring was forged when dead stars collided.
Stars fuse elements in their cores only up to iron. Heavier ones like gold, platinum and uranium need extreme floods of …
- The hottest planet is not the one closest to the Sun.
Mercury orbits nearest the Sun, yet Venus is hotter: 464 °C on average at the surface, even though it receives only a …