ASTR 1345: Chapter 9 Vegabonds of the Solar System
34 Cards in this Set
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Composition of Comets
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- ice
- dust
- rock
- frozen gasses
- dry ice (C02)
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Sublimation of Comets
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frozen material and ice directly changes into gas from solid state without becoming a liquid
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A = hydrogen envelope
B = tail
C = coma
D = nucleus
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Hydrogen Envelope
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sparse envelope released by breakup of molecules (such as H20)
- not seen in visible light
- millions of km in length
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Dust Tail
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blown off the nucleus by Sun's radiation pressure
- made of dust particles
- broad, diffuse and curved
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Ion Tail
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blown off by the solar wind (ionized particles from sun)
- made of plasma
- mostly straight
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Both Ion Tail and Dust Tail can reach ____
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1 AU (108 km)
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Coma
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dense sphere of material evaporated hen the comet reaches the inner solar system
- 100,000 km across
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Nucleus
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relatively stable and solid (dirty snowball)
- mixed dust/ice
- H20, methane, amonia, C02
- 10 km across
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Space crafts that visited Halley's Comet (1986)
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- Vega 2 (soviet space craft)
- Giotto (european space craft)
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Nucleus of Halley's Comet (1986)
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irregular
- size: 15 x 10 km
- very dark
- several jets streaming out form coma and tail
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Spacecraft that landed on Comet 67P/Churyumov-Gerasimenko
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Philae from Rosetta spacecraft (Nov 12th, 2014)
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Comets orbits are ___
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highly elliptical
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Comets orbits extend ___
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far beyond Pluto
- as far as 50,000 AU
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Comets orbits tend to be ____
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inclined relative to the ecliptic
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In all cases, comet tails are ___
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directed away from Sun by solar wind
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Ion Tails vs. Dust Tails
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differ in shape because of the different responses of gas and dust to the forces acting on them
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Ion Tail (Type 1)
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pushed rapidly, straight back by solar wind
- straight tail
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Dust Tail (Type 2)
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gently pushed back by solar radiation
- dust particles left behind are in longer orbits
- curved tail
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Oort Cloud
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long-period comets
- hundred of thousands, some even million of years long orbit
- all inclinations, all orientations, both pro and retrograde (never come anywhere near Sun)
- occasionally pulled into inner solar system due to gravitational tug by nearby star
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Kuiper Belt
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short-period comets
- less than 200 years
- prograde orbits laying close to ecliptic
- circular orbits (between 30-100 AU)
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Meteoroid Swarm
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formed each time a comet rounds the Sun, some cometary material becomes dislodged (30 tons per second if comet is within an AU from Sun)
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Micro-meteoroids
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over course of time, the swarm gradually disperses along orbit, and become more or less smoothly spread all the way around parent comet's orbit following the same path -> these small objects are micrometeoroids
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Meteor Shower
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if Earth's orbit happens to intersect the orbit of a young cluster of meteoroids
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Do Comets always have a tail?
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No
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Where do Comets belong?
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Our solar system
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Away from the Sun, Comets are made up of ___
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just a nucleus
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Nucleus of Halley's Comet is not ____; looks like ____
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not spherical; looks like a rock
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Halley's Comet orbit is ___ around the Sun
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76 years
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Rosetta Spacecraft launched in ___
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2004
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Philae Lander landed on surface of ___
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Comet P67
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The tail of a comet becomes longer when ___
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closer to the Sun
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The tail always points ___
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away from the Sun
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(Venus) Continents defined by ___
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eleveation
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ASTR 1345: Chapter 9 Vegabonds of the Solar System