Facts about space
Space facts are mostly a lesson in scale. Days longer than years, storms wider than Earth, light that left its star before the pyramids existed — the numbers stop being intuitive very quickly. Every entry here comes from established astronomy and includes a short explanation of what causes the effect, so the fact holds up when someone asks the obvious follow-up question at the dinner table.
A day on Venus is longer than a year on Venus.
Venus takes about 243 Earth days to rotate once on its axis, but only about 225 Earth days to travel around the Sun. It also spins backwards compared with most planets, so the Sun rises in the west.
A sugar cube of neutron star material would weigh hundreds of millions of tonnes.
A neutron star packs more mass than the Sun into a ball about 20 kilometres across. Its material is so dense that a single cubic centimetre would weigh about as much as a mountain.
The tallest volcano in the solar system is on Mars, and it is nearly three times the height of Everest.
Olympus Mons rises about 22 kilometres above the Martian plains and is roughly the size of Poland at its base. Its slopes are so gentle that a person standing on it would not notice they were on a mountain.
The footprints left on the Moon could last for millions of years.
The Moon has no wind, no rain and no flowing water to disturb the surface. The boot prints from the Apollo landings are still there, exactly as they were made.
The sunlight hitting you right now left the Sun about eight minutes ago.
Light travels at roughly 300,000 kilometres per second, and the Sun is about 150 million kilometres away. The trip takes eight minutes and twenty seconds.
Saturn is so light for its size that it would float in a big enough bathtub.
Saturn's average density is about 0.69 grams per cubic centimetre, less than water. It is the only planet in the solar system less dense than water.
Jupiter's Great Red Spot is a storm larger than Earth that has raged for at least 190 years.
The spot has been observed continuously since 1831, and possibly since the 1660s. Wind speeds around its edge reach more than 400 kilometres per hour.
Astronauts on the International Space Station see about 16 sunrises every day.
The station circles Earth roughly every 90 minutes at about 28,000 kilometres per hour. Each orbit brings a sunrise and a sunset.
Neptune was discovered with pen and paper before anyone saw it through a telescope.
Uranus was not moving quite as Newton's laws predicted. The French astronomer Urbain Le Verrier calculated where an unknown planet would have to be to explain the difference, and in 1846 a Berlin observatory found Neptune within one degree of his prediction.
Voyager 1, launched in 1977, is the farthest human-made object and is still sending data home.
The probe crossed into interstellar space in 2012 and is now more than 160 times farther from the Sun than Earth is. A radio signal from it takes almost a day to reach us.
Pluto has not completed a single orbit of the Sun since it was discovered in 1930.
One Pluto year lasts about 248 Earth years. Pluto will finish its first full orbit since discovery in the year 2178.
There are more stars in the observable universe than grains of sand on all the beaches on Earth.
Astronomers estimate the observable universe holds somewhere around 10 to the power of 22 to 10 to the power of 24 stars. Estimates for grains of sand on Earth's beaches come out at roughly 10 to the power of 18 to 10 to the power of 19.