Science Kids - Fun Science & Technology for Kids!
Science for Kids Math for Kids English for Kids


Fun science experimentsCool science games & activitiesAmazing science factsScience quizzesScience fair projectsScience lesson plans and class ideasScience images, photos & picturesScience videosScience topics
Fun Space Facts for Kids

Explore our amazing space and astronomy facts. Learn about all kinds of different space topics that are sure to surprise.

Space & Astronomy Information Guide for KidsEasy Space Definitions

Check out our space & astronomy information guide for kids that contains a glossary of important words and easy definitions to help explain them. Understand what these space and astronomy terms mean in simple language.


  • Asteroid: Asteroids are small solar system bodies that orbit the Sun. Made of rock and metal, they can also contain organic compounds. Asteroids are similar to comets but do not have a visible coma (fuzzy outline and tail) like comets do.

  • Asteroid Belt: The asteroid belt lies roughly between the orbits of Mars and Jupiter in the Solar System. It is home to a large amount of irregular shaped asteroids that range in size from dust through to the dwarf planet Ceres.

  • Astronaut: An astronaut (also known as cosmonaut) is someone trained to be a crew member of a spacecraft. While the word astronaut usually refers to space travel professionals it can also include normal people who have the privilege of traveling into space.

  • Black Hole: Black holes are areas of space where gravity is so strong that nothing can escape, not even light! They are formed when massive stars collapse at the end of their life cycle.

  • Comet: A comet is a relatively small solar system body that orbits the sun. When close enough to the Sun they display a visible coma (a fuzzy outline or atmosphere due to solar radiation) and sometimes a tail.

  • Dwarf planet: An object orbiting the Sun that is large enough to be rounded by its own gravity but is not gravitationally dominant in its orbital area and is not a moon. There are currently five recognized dwarf planets: Pluto, Ceres, Eris, Makemake & Haumea.

  • Earth: Earth is the fifth largest planet in the Solar System and third from the Sun. It was formed around four and a half billion years ago and is the only place in the Universe where life is known to exist.

  • Galaxy: A galaxy is a large group of stars, dust, gas and dark matter held together by gravity. They vary in size with some containing millions of stars while others could contain as many as a trillion. They can also form in different shapes such as elliptical galaxies and spiral galaxies.

  • Halley’s Comet: Halley’s Comet (or Comet Halley as it is also known) is the most well known comet in the Solar System. It orbits the Sun and can be seen with the naked eye from Earth around every 75 years, returning for its next visit sometime in 2061.

  • Jupiter: Jupiter is the largest planet in our solar system. It features the famous ‘Red Spot’ and a large number of orbiting moons.

  • Mars: Mars, or the 'Red Planet' as it is sometimes known, is the fourth planet from the Sun. It features a dusty, rocky surface, relatively calm conditions and a thin atmosphere.

  • Mercury: Mercury is the closest planet to the Sun in the Solar System. As well as being very hot, it features a barren, crater covered surface which looks similar to the Moon.

  • Meteor: A meteoroid that burns up as it passes through the Earth’s atmosphere is known as a meteor. If you’ve ever looked up at the sky at night and seen a streak of light or ‘shooting star’ what you are actually seeing is a meteor.

  • Meteorite: A meteoroid that survives falling through the Earth’s atmosphere and colliding with the Earth’ surface is known as a meteorite.

  • Meteoroid: A meteoroid is a small rock or particle of debris in our solar system. They range in size from dust to around 10 metres in diameter (larger objects are usually referred to as asteroids).

  • Milky Way: The Milky Way is a spiral galaxy where our Solar System and Earth are located.

  • Moon: The Moon is a natural satellite which orbits the Earth. It is around a quarter the size of Earth and can be easily seen in the night sky. While other planets in the Solar System have ‘moons’, they are usually referred to by name, such as Jupiter’s Ganymede, or as natural satellites.

  • Neptune: Neptune is the eighth planet from the Sun and is nearly four times the size of Earth. It features strong winds and violent weather.

  • Planet: A planet is an object orbiting a star that is large enough to be rounded by its own gravity. It is also gravitationally dominant in its orbital area but not large enough to cause thermonuclear fusion (like stars do). There are eight planets in the Solar System.

  • Pluto: Pluto was the furthest planet from the Sun until it was demoted from a planet to a dwarf planet in 2006.

  • Saturn: Saturn is the second largest planet in our solar system, the sixth planet from the Sun and features an impressive system of rings.

  • Small Solar System Body: Objects that orbit the Sun but aren’t planets or dwarf planets are known as small solar system bodies, these include comets, asteroids and other small bodies.

  • Solar System: The solar system includes the Sun and all the objects that orbit around it due to its gravity, including Earth.

  • Star: A star is a huge, bright ball of burning gas that is held together by gravity. Stars contain mostly hydrogen as well as helium and smaller amounts of other elements. The Sun is the closest star to Earth.

  • Sun: The Sun is a star and the biggest object in the Solar System, it burns brightly in the center as planets and other objects orbit around it. It has a diameter around 110 times bigger than the Earth’s and is located around 150 million kilometres (93 million miles) away.

  • Universe: The Universe is made up of everything that exists, including planets, stars, galaxies and all forms of matter and energy.

  • Uranus: Uranus is the third largest planet in the Solar System and seventh planet from the Sun. Uranus rolls like a barrel rather than spinning like Earth and was the first planet discovered by telescope.

  • Venus: Venus is the second closest planet to the Sun. It is similar in size to Earth and features thick a thick atmosphere which locks in heat as the surface rages with active volcanoes.




Science Kids ©  |  Home  |  About  |  Topics  |  Experiments  |  Games  |  Facts  |  Quizzes  |  Projects  |  Lessons  |  Images  |  Videos  |  Privacy  |  Sitemap  |  Updated: Oct 9, 2023