Universe Vocabulary

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Across
  1. 2. A collection of thousands to billions of stars held together by gravity. The galaxy we live in is called the Milky Way.
  2. 8. An object that orbits another object. A moon is actually a satellite. We also say satellite to refer to spacecraft people build that orbit Earth, other planets, moons, asteroids, or other objects out in space.
  3. 9. An icy rock that lets off gas and dust, which may form tails when it is flying close to a sun.
  4. 11. An object, thought to be a rapidly rotating neutron star. It releases short pulses of radio waves and other electromagnetic radiation.
  5. 12. It’s not a year, or an amount of time at all. It’s the distance light travels in one year. It’s the same as 5,878,499,810,000 miles (or 9,460,538,400,000,000 meters). When things are very far away, it’s easier to talk about their distance in light years than millions or billions or trillions of miles.
  6. 13. The star in the center of our solar system.
  7. 15. of Light Light is the fastest thing in the universe. It travels 186,282 miles (299,792,458 meters) every second.
  8. 16. A force that pulls matter together.
  9. 18. A natural object that travels around a bigger natural object. Planets can have moons. Dwarf planets can have moons. Even some asteroids have moons! Astronomers usually call them satellites or natural satellites.
  10. 20. A meteoroid that lands on the surface of a planet.
  11. 22. A cloud of dust or gas found between stars.
  12. 25. The constant stream of particles and energy emitted by the sun.
  13. 26. The basic building block of matter. It is made of protons, neutrons, and electrons. There are many different kinds of atoms. For example, the simplest atom with one proton and one electron is a hydrogen atom. An atom with six protons, six neutrons, and six electrons is a carbon atom.
  14. 29. The curved path that a planet, satellite, or spacecraft moves as it circles around another object.
  15. 30. The streak of light caused when a meteoroid enters a planet’s atmosphere and starts to burn from the heat of friction.
  16. 31. Objects that are round and orbit the sun, just like planets do. But unlike planets, dwarf planets are not able to clear their path around the sun. That means there are other objects orbiting at roughly the same distance from the sun. A dwarf planet is much smaller than a planet (smaller even than Earth's moon), but it is not a moon. Pluto is the best known of the dwarf planets.
  17. 32. A place in space where matter and light cannot escape if they fall in.
  18. 33. The stuff that everything is made of. Atoms are a tiny bit of matter. Big planets have lots of matter. Even you are made of matter!
  19. 34. A ball of shining gas, made mostly of hydrogen and helium, held together by its own gravity. Turning hydrogen into helium creates the energy that makes stars shine.
Down
  1. 1. All of space and time, and everything in it. It’s everything ever!
  2. 3. Rocks floating around in space. Some are the size of a pick-up truck. Others are hundreds of miles across.
  3. 4. A large, bowl-shaped dent in the ground. They can be caused by an explosion or the impact of a meteorite.
  4. 5. A set that includes a star and all of the matter that orbits it, including planets, moons, asteroids, comets, and other objects.
  5. 6. A group of stars in the sky. They're often named after an animal, object, or person. The stars form certain patterns based on where you are. We have one view of stars here on Earth, but from another solar system or galaxy, the constellations would look different.
  6. 7. A burst of energy and particles from the sun. It releases gases, radiation waves, and magnetic storms.
  7. 8. The explosion of a star that makes it as bright as a whole galaxy.
  8. 10. Compact area in the center of a massive galaxy that is around a supermassive black hole. They are some of the brightest objects in the universe and can be observed across the entire electromagnetic spectrum.
  9. 14. A little chunk of rock in space smaller than a pick up truck. If it were bigger, it would be an asteroid.
  10. 17. An empty space that doesn't have any matter.
  11. 19. A large body in outer space that circles around the sun or another star.
  12. 21. A planet that freely floats between stars or one that orbits a star outside our solar system.
  13. 23. The gases held by gravity around Earth and around other planets. "Atmosphere" can also be used to talk about gases around stars.
  14. 24. The universe seen as an orderly, harmonious whole.
  15. 27. A very dense star made mostly of neutrons. It has very powerful gravitational force nearby because the whole mass of a star is pulled into one object just a few miles across.
  16. 28. The outer atmosphere of a star.