Space Facts for Kids
Out-of-this-world facts about the universe
Mercury is the closest planet to the Sun, yet it has water ice hidden in permanently shadowed craters near its poles. Because Mercury's axis isn't tilted, the bottoms of some polar craters never see sunlight and stay frozen.
Gamma-ray bursts are the most powerful explosions in the universe, releasing more energy in seconds than the Sun will emit over its entire lifetime. They are thought to occur when massive stars collapse into black holes or when two neutron stars merge.
Without gravity pulling on them, astronauts' bones and muscles begin to weaken in space. Astronauts on long missions can lose up to 1-2% of their bone density per month, which is why they exercise for up to 2 hours every day on the ISS.
Nebulae are enormous clouds of gas and dust in space where new stars are born. The most famous is the Orion Nebula, which is about 1,344 light-years from Earth and contains hundreds of young stars that are only a million years old.
In 2019, scientists captured the first-ever photograph of a black hole. The image showed the supermassive black hole at the center of the galaxy M87, which is 6.5 billion times the mass of our Sun and 55 million light-years away.
The Sun's surface is covered in sunspots — dark regions where strong magnetic fields prevent hot gas from rising. Some sunspots are larger than Earth itself! The number of sunspots rises and falls on an 11-year cycle.
Astronauts who have been on spacewalks report that space has a smell — something like hot metal, seared steak, or welding fumes. The smell clings to their spacesuits and equipment when they come back inside the spacecraft.
Saturn is the least dense planet in our solar system — it's actually less dense than water! If you could find a bathtub big enough, Saturn would float in it. Saturn is made mostly of hydrogen and helium gas.
The universe is not only expanding — it's expanding faster and faster over time. Scientists discovered this in 1998 and believe a mysterious force called dark energy is responsible. This discovery was so shocking it won the Nobel Prize in Physics.
Ganymede, one of Jupiter's moons, is the largest moon in the entire solar system — even bigger than the planet Mercury! It is also the only moon known to have its own magnetic field and is thought to have a liquid saltwater ocean beneath its icy surface.