Space Glossary

1. ours galaxy
3. A vast collection of stars, gas, and dust, typically 10,000 to 100,000 light-years in diameter and containing billions of stars (from galaxias kuklos, Greek for “circle of milk,” originally used to describe our own Milky Way
5. Greek for “circle of animals.” It’s the set of constellations situated along the ecliptic in the sky, through which the Sun, Moon, and planets move.
6. Most are only a few miles in diameter and are found between the orbits of Mars and Jupiter, too small and far away to be seen easily in a small telescope.
7. An event that occurs when the shadow of a planet or moon falls upon a second body. A solar eclipse occurs when the Moon’s shadow falls upon Earth, which we see as the Moon blocking the Sun.

1. A brief streak of light caused by a small piece of solid matter entering Earth’s atmosphere at tremendous speed (typically 20 to 40 miles per second). Also called a “shooting star.”
2. A glow in the night sky or around your observing site caused by artificial light. It greatly reduces how many stars you can see.
4. A concentration of mass so dense that nothing — not even light — can escape its gravitational pull once swallowed up. Many galaxies (including ours) have supermassive black holes at their centers
8. a “dirty snowball” of ice and rocky debris, typically a few miles across, that orbits the Sun in a long ellipse.
9. A massive ball of gas that generates prodigious amounts of energy (including light) from nuclear fusion in its hot, dense core