asteroids, comets and meteors

• Asteroid belt is between Mars and Jupiter
• Asteroids, comets, and meteors are chunks of rock, ice, and metal left over from the formation of our solar system 4.6 billion years ago.
• There are currently about 1.3 million known asteroids, and more than 3,800 known comets.
• meteoroid: A “space rock” a relatively small object traveling through space, between the size of a grain of dust and a small asteroid.
• meteor: A meteoroid that enters Earth’s atmosphere and burns up.
• meteorite: A meteoroid, especially one that has hit Earth’s surface.
• asteroid: A rocky object that orbits the sun and has an average size between a meteoroid and a planet.
• comet: An object made mostly of ice and dust, often with a gas halo and tail, that sometimes orbits the sun.
• The -ite ending is often used in the names of rocks and minerals, such as anthracite
• The large Chicxulub crater in Mexico is thought to be from the meteorite strike that caused the extinction of many dinosaurs. The biggest impact crater on Earth is the Vredefort crater in South Africa—it was originally 185 miles across.
• Because meteors streak so brightly across the sky, the adjective meteoric is sometimes used metaphorically to describe something sudden, brilliant, and swift, especially in the phrase meteoric rise.
• The study of meteors is called meteoritics, and a person who studies meteors is called a meteoriticist
• A meteor shower is what happens when a lot of meteors enter the atmosphere during a relatively short period of time.
• meteor swarm — a large number of meteoroids moving in a parallel path
• Some meteor showers occur when Earth passes through the path where a comet has traveled—the meteors in these showers are comet fragments that have fallen off and been pulled in by Earth’s gravity
• Some particularly wellknown meteor showers include the Perseids (in mid-August), the Leonids (in mid-November), and the Eta Aquariids (in early May), which are linked to the famous Halley’s comet.
• Asteroids can also be called minor planets or planetoids.
• Where do asteroids come from? They’re essentially space debris left over from when the solar system formed. The word asteroid comes from the Greek asteroeidorḗs meaning "starry" or "starlike” (to be clear, asteroids orbit stars, which makes them more like tiny planets).
• There are currently more than 1 million known asteroids in the solar s ys tem. Mos t of th e asteroids we know about are in the asteroid belt, a kind of junkyard for asteroids between Mars and Jupiter.
• Comets are known for having a tail, which is really the trail that happens when this gaseous dust cloud is blown by solar wind or heat.
• the

  word comet comes

  fr o m t h e Gr e e k

  komḗtēs, meaning

  “having long hair”!
• Most comets come from outside of or from the edge of the solar system.
• Many come from the far-out regions known as the Oort Cloud (where there are billions of them) and the Kuiper Belt.
• Halley’s comet is known for reappearing about every 76 years (it was last here in 1986, and you can catch it again in 2061).
• Many comets have a much longer orbit period, but some are shorter—Encke’s comet comes around every 3.3 years (October 2023 was its last appearance).
• The term shooting star (or falling star) is just a more poetic name for a meteor, which can look a little bit like a star as it makes a bright streak through the sky.
• An asteroid hitting Earth would be a cataclysmic event. If you look closely, you can see the comet’s tail streaming behind it.
• Scientists believe the meteorite discovered in the desert is a fragment of an asteroid formed in the early days of the solar system.
• a particularly bright meteor can be called a bolide or fireball, especially if it explodes.
• Comets consist mostly of ice, dust, and some rocky bits—they are sometimes nicknamed “dirty snowballs" for this reason.