Chapter 9 Book Notes

Chapter 9 Book Notes - Astronomy 180 Chapter 9: Vegabonds...

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Astronomy 180 Chapter 9: Vegabonds of the Solar System (Pages 239 - 266) I. Asteroids: The Minor Planets Asteroid (minor planet) – any of the rocky objects larger than a few hundred meters in diameter (and not classified as a planet or moon) that orbits the Sun II. Asteroids: The Minor Planets: Most asteroids orbit the Sun between Mars and Jupiter Sicilian astronomer Giuseppe Piazzi in 1801 discovered the first asteroid Asteroid belt – a 1½-AU-wide region between the orbits of Mars & Jupiter in which most of the asteroids are found Belt asteroid – an asteroid whose orbit lies in the asteroid belt Using the technique of astrophotography, hundreds of asteroids were discovered (late 1800s) Ceres, the largest asteroid, accounts for about 30% of the mass of all the known asteroids combined Only 3 asteroids – Ceres, Pallas, and Vesta – have diameters greater than 300km III. Asteroids: The Minor Planets: Jupiter’s gravity creates gaps in the asteroid belt Kirkwood gaps – gaps in the spacing of asteroid orbits discovered by Daniel Kirkwood caused by gravitational attractions of planets The asteroids in the belt are actually 10 million km apart – contrary to how entertainment media portrays them Families of asteroids orbit together (due to impacts) if after impact they do not reform Some asteroids are satellites of other asteroids – there are about 57 that have been observed thus far IV. Asteroids: The Minor Planets: Asteroids exist outside the asteroid belt Stable Lagrange points – locations throughout the solar system where the gravitational forces from the Sun and a planet keep space debris trapped The gravitational pulls of Jupiter and the Sun work together to hold asteroids in orbit at these locations Trojan asteroid – one of several asteroids at stable Lagrange points that share Jupiter’s orbit about the Sun Apollo asteroid – an asteroid that is sometimes closer to the Sun than the Earth is Typical rotation periods for asteroids are between 5 and 20 hours (1998 KY26 rotates once every 10.7 minutes – fastest rotating object in the solar system) The sun is not the only star with an asteroid belt – 2001 Zeta Leopris (70LY from Earth) has one, as well V. Comets Comet – a small body of ice and dust in orbit about the Sun. While passing near the Sun, a comet’s vaporized ices give rise to a coma, tails, and a hydrogen envelope VI. Comets: Comets come from far out in the solar system Today, the solar system is thought ot contain 2 reservoirs of comets; most from the Kuiper belt Kuiper belt – a doughnut-shaped ring of space around the Sun beyond Pluto that contains many frozen comet
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This note was uploaded on 04/18/2008 for the course AST 180 taught by Professor Barlow during the Fall '08 term at N. Arizona.

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Chapter 9 Book Notes - Astronomy 180 Chapter 9: Vegabonds...

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