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Ch Asteroids, Comets, & Meteoroids

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Presentation on theme: "Ch Asteroids, Comets, & Meteoroids"— Presentation transcript:

1 Ch. 28.4 Asteroids, Comets, & Meteoroids
Mrs. Marques

2 Terms to Know… Asteroid Comet Kuiper Belt Oort cloud Meteor meteoroid

3 Asteroids: large rock fragments that orbit the sun in elliptical orbits.
Largest known asteroid is Ceres (1,000 km diam.)…also considered a dwarf planet b/c its gravity has caused it to be round.

4 Asteroid belt is located b/t Mars and Jupiter and contains most asteroids.
Three types based on composition Carbon (these asteroids are dark) Silicate (like Earth rocks) Fe, Ni (rare, shiny-metallic surface) Near-Earth Asteroids: very small percentage…asteroid detection programs monitor their movements.

5 Comets: ice, rock, dust, have tails—highly elliptical orbits around sun.
Halley’s Comet-passes Earth every 76 yrs (next = 2061). Also famous: Hale-Bopp (shown below, 1997), McNaught (2007)

6 Parts of a comet: Head Core (aka nucleus): rock, metals, ice Coma: cloud of gas/dust 2 Tails Ion tail: Solar wind pushes gas away from the comet’s head so it always points away from the sun no matter which direction the comet is going. Dust tail: curves behind the comet


8 Where do comets come from?
Some from Kuiper Belt (ring of icy bodies, including some dwarf planets, beyond Neptune’s orbit) Most from Oort Cloud (spherical cloud of dust/ice) Could reach as far back as halfway to a near star.

9 Some comets can have orbits up to a few million years
Some comets can have orbits up to a few million years! Those >200 years are called long-period comets. Short period comet: <200 years to orbit sun Long period comet: > 200 years to orbit sun Meteoroids: small bits of rock/metal Small meteoroids: detached comet pieces Large meteoroids: result of colliding asteroids.

10 Meteors: shooting stars or fireballs (bright b/c friction of entering our atmosphere)
Meteor shower: occur at the same time each year with the orbits of comets (comet leftovers).

11 Meteorites: meteor leftovers that made it to Earth’s surface
Stony (most are stony)…carbon based Iron…(easier to find b/c metallic) Stony-iron (rarest)


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