The terms asteroid, meteor, meteorite, and even comet are often used interchangeably...but what is the difference?
What is a comet?
Comets are also composed of material left over from the formation of our solar system and formed around the same time as asteroids. However, asteroids formed toward the inner regions of our solar system where temperatures were hotter and thus only rock or metal could remain solid without melting. Comets formed at farther distances from the Sun, beyond what we call the frost or snow line and past the orbits of Mars and Jupiter, where temperatures were low enough for water to freeze.
Comets are thus chunks of frozen gas, rock, ice, and dust that orbit our Sun earning them the nickname of dirty snowballs. They are identified by their tails which consist of trailing jets of gas and dust that has been melted off as a comet approaches too close to the Sun.
Meteorites are meteors that survive the dive through the Earth’s atmosphere
What is a meteor and a meteorite?
A meteor is simply an asteroid that attempts to land on Earth but is vaporized by the Earth’s atmosphere. The resistance on the rock due to the Earth’s atmosphere causes its temperature to rise. We sometimes see the glowing hot air created by these burning meteors and dub them “shooting stars.” Meteor showers occur when the Earth passes by many meteors at once. For example, if chunks of a comet melt off as it passes close to the Sun, this debris can be left behind to later dazzle us Earthlings with a meteor shower.
Meteorites are meteors that survive the dive through the Earth’s atmosphere and manage to land on the surface of our planet. They are typically composed of either iron or stone, i.e. a mix of oxygen, silicon, magnesium, iron, and other elements.
Studying asteroids helps us understand the formation of our solar system and how our planet came to be. We don’t just have to wait for meteorites to find us to know more about their composition, however. The OSIRIS-Rex mission to the asteroid Bennu aims to take samples from the asteroid and bring them back to Earth. You can learn more about why Bennu was chosen for such a special mission and check out the countdown to the spacecraft’s approach to the asteroid on the OSIRIS-Rex mission page.
Until next time, this is Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Everyday Einstein on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at email@example.com.
Image courtesy of nasa.gov