Asteroids, Trans-Neptunian Objects, Oort Cloud & Comets Asteroids: the “minor planets” (The Asteroid Belt) - There are 100,000s of relatively small rocky bodies orbiting around the Sun between the orbit of Mars and the orbit of Jupiter the Asteroid Belt - At a distance of 2-3.5 AU mainly with large eccentricity and inclination - These are “left-over” from the objects (“planetesimals”) that formed the planets, but will never form a planet - Their combined mass is about that of the Moon or a little less - There are a few large objects, more smaller objects and plenty of tiny objects. - These were planetesimals which never formed a planet due to the strong gravitational pull of Jupiter. - These planetesimals lost most of their “ice” and are made mainly of rocky materials. - There are gaps in the belts due to Jupiter gravitational pull (resonance).
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Asteroids, Trans-Neptunian Objects, Oort Cloud & Comets · 2018. 9. 10. · The Oort Cloud It is a hypothesized spherical cloud of comets some 50,000AU from the sun (about 1 light
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Asteroids: the “minor planets” (The Asteroid Belt) - There are 100,000s of relatively small rocky bodies orbiting around the Sun between the orbit of
Mars and the orbit of Jupiter the Asteroid Belt - At a distance of 2-3.5 AU mainly with large eccentricity and inclination
- These are “left-over” from the objects (“planetesimals”) that formed the planets, but will never form a planet
- Their combined mass is about that of the Moon or a little less - There are a few large objects, more smaller objects and plenty of tiny objects. - These were planetesimals which never formed a planet due to the strong gravitational pull of
Jupiter. - These planetesimals lost most of their “ice” and are made mainly of rocky materials. - There are gaps in the belts due to Jupiter gravitational pull (resonance).
It is the source of very long period comets. The largest known object in the Oort cloud: Sedna, 1200-1800km in diameter, 76-892AU!
Comets - A comet is an icy small solar system body that, when close enough to the Sun, displays a visible
fuzzy coma and a tail, due to the solar radiation and wind, on the nucleus of the comet. - The comets are icy/rocky bodies coming from the Kuiper Belt (scattered siks) or from the Oort
Cloud. - Comets range in size between a few 100m to a few km - Orbital periods range from a few yrs to 1,000s of yrs - Comets that have passed many times close to the sun have lost their volatile (ice, water,
methane, ammonia) and are similar to asteroids (rocky material). - A comet has a Nucleus, a Coma, a gas tail and a dust tail.
The Nucleus Composed of rock, dust, water ice and frozen volatiles CO, CO2, NH3, CH4
The Coma - The solar radiation causes the volatile of the comet to vaporize and stream out of the nucleus
carrying dust away with them. - The streams of dust and gas ejected from the nucleus forms the coma (it is like a very tenuous
atmosphere around the nucleus), which reflects the sunlight and also glows due to ionization. The coma of Comet Holmes
The dust and gas escaping are blown away by the Sun radiation and wind forming the tails of the comet. The comet has a dust tail and a gas or ion tail. The Tails of the comet: The gas in the tail is ionized “ion” tail The dust tail reflects sunlight The ion tail glows due to ionization The dust tail is always behind in the comet’s orbit (trailing behind) The ion tail always points away from the Sun, as it is blown away by solar wind.