Space Facts for Kids
Out-of-this-world facts about the universe
Our entire solar system orbits the center of the Milky Way galaxy. But the Milky Way is so enormous that this trip takes about 225 million years — a period called a 'cosmic year' or 'galactic year.' Since Earth formed, we've only completed about 20 of these cosmic laps.
The first human to travel to space was Soviet cosmonaut Yuri Gagarin, who orbited Earth on April 12, 1961, aboard Vostok 1. His entire mission lasted just 108 minutes. Gagarin is celebrated as a hero around the world, and April 12 is now called Yuri's Night.
One of the biggest mysteries in solar physics is why the Sun's outer atmosphere (corona) is millions of degrees hotter than its visible surface. The surface is about 10,000°F but the corona reaches over 3.5 million°F — it's like the air around a campfire being hotter than the flames!
Mars has polar ice caps at both poles, but they're not just made of water ice. Mars's polar caps contain dry ice — frozen carbon dioxide — that expands and shrinks with the Martian seasons. In winter, CO2 gas freezes directly onto the surface.
According to Einstein's theory of relativity, time passes more slowly for objects moving at high speed. Astronaut Scott Kelly spent nearly a year on the ISS and returned to find he had aged 6 milliseconds less than his twin brother on Earth.
All the planets in our solar system orbit the Sun in roughly the same flat plane, called the ecliptic. This is because our solar system formed from a spinning disk of gas and dust, and the planets formed within that disk.
Infrared telescopes like the James Webb Space Telescope can 'see through' clouds of gas and dust that block visible light. This allows astronomers to observe stars forming inside dusty nebulae and to spot distant galaxies whose light has been stretched by the expanding universe.
Mars appears red because its surface is covered in iron oxide — rust! Billions of years ago, Mars had liquid water and a thicker atmosphere. When that water disappeared, the iron in the rocks reacted with oxygen and turned into rust.
When a space rock survives its fiery fall through Earth's atmosphere and lands on the ground, it's called a meteorite. Scientists have found over 50,000 meteorites on Earth. Some are even pieces of Mars or the Moon, blasted off by ancient asteroid impacts!
NASA has a 'planetary protection' program dedicated to making sure spacecraft don't accidentally bring Earth microbes to other planets — or bring alien microbes back to Earth. Spacecraft bound for places that might have life, like Mars or Europa, are meticulously sterilized.