Asteroid belt Located between Mars and Jupiter. Here are a few key areas where they’re found, ordered by their proximity to Earth. We tend to focus on asteroids when talking about potential collisions, because they’re more likely to hit us than other stuff like comets, but still big enough to pose a threat.Īlso called “bolides” or “fireballs” if they’re brightĪsteroids and comets aren’t rogue wanderers flying through space-they orbit the sun, just like the planets. Perhaps most useful to remember is that when near-Earth objects (including asteroids, comets and meteoroids) enter the atmosphere, they’re called meteors and if there’s anything left when they hit the ground, the resulting object is called a meteorite. Despite the name, they can still be quite far away from Earth during most of their orbit. Near-Earth object A small (non-planet) object in the inner solar system. We can learn a lot about asteroids and planets by studying meteorites that fall to Earth. If they’re big enough, meteors become meteorites when they hit the ground. Meteorite A piece of rock or metal that has fallen to the surface of Earth from outer space.
Comets, asteroids and meteoroids can all become meteors. When they hit the atmosphere at night, they’re seen as shooting stars (and if they’re extremely bright, they are also known as fireballs or bolides). Meteor An object from outer space that enters Earth’s atmosphere. Heat melts the ice, which boils off into space and then freezes again … we see those ice crystals twinkling in the sunlight as the tail of the comet. GLOSSARY sublimation The equivalent of melting in space. They look different from asteroids because of the distinctive tail (or tails) of particles that stream behind them, caused by Asteroids usually have an irregular (non-round) shape, because they don’t have enough gravity to squish them into a ball. Asteroid A rocky object that orbits the sun, smaller than a dwarf planet but bigger than a meteoroid. Meteoroid A small rocky object in space, considerably smaller than an asteroid (typically, no bigger than 10 metres across). Dwarf planet A large object that doesn’t meet all the criteria to be either a planet or a moon. They don’t necessarily need to orbit planets-sometimes they orbit asteroids or dwarf planets. Moon A celestial body that orbits another celestial body that isn’t a star. GLOSSARY ice giants Planets mostly composed of heavier elements with low boiling points, like oxygen, carbon, nitrogen and sulfur. GLOSSARY gas giants Planets mostly composed of light elements with low boiling points, like hydrogen and helium. GLOSSARY rocky planets Planets that are mostly composed of rocks or metals. Planet A large, round object that orbits a star and has an orbit that’s mostly clear from other objects. The objects in our solar system come in many different shapes and sizes and with lots of different names, so let’s start by clearing up some terminology.
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