Astronomy: Chapter 12.3 Flashcards
Describe a comet and discuss its probable composition and structure.
Celestial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit.
It appears as a glowing head with an extended tail. The tail can be longer than an AU. It is produced by an icy nucleus that remains frozen and inactive while it is away from the sun. The suns heat begins to vaporize the ices, releasing gas and dust. The pressure of sunlight and the solar wind pushes the gas and dust away, forming a long tail. The comets nuclei contain ices of water, carbon dioxide, carbon monoxide, methane, ammonia, etc. Images show that comet nuclei are irregular in shape and very dark, with jets of gas and dust spewing from active regions on the nuclei.
Describe the probable origin of comets and their motion around the sun.
Possible origin is that is comes from the Kulper belt, past pluto.
Distinguish between meteoroids, meteors, and meteorites and describe the different types of meteorites.
Meteors: flash across the sky in momentary streaks of light. They are bits of rock and metal falling into Earth’s atmosphere and bursting into incandescent vapor about 50mi above the ground, adding about 40,000 tons per year to Earth’s mass.
Meteoroids: Before the meteors fiery plunge, it is called a meteoroid. Most meteoroids are the size of dust, grains of sand, or tiny pebbles. Most weigh less than 1 gram.
Meteorite: if a meteoroid survives onto Earth’s surface, it is called a meteorite. Meteorite can be divided into three main categories. Iron Meteorites are solid chunks of iron and nickel. Stony meteorites are silicate masses that resemble Earth rocks. Stonyiron meteorites are mixtures of iron and stone.
Describe the characteristics of meteors and meteor showers, and explain how they relate to cometary orbits.
Meteors are small bits of matter heated by friction to incandescent vapor as it falls into Earth’s atmosphere.
Meteors in a shower are debris left behind as a come’ts icy nucleus vaporizes. The rocky and metallic bits of matter spread along the comet’s orbit. If earth passes through such material, you can see a meteor shower.
Sketch the orbit of a comet around the sun, showing the comet and its tail in several positions. Explain why the tail of the comets point the way it does.
Sun solar wind pushes the tail away from the sun.
Describe the appearance and composition of asteroids, and their three major locations in the solar system.
Made of rocky and/or iron-nickle material and most are found in an orbit between Mars and Jupiter. Most are pitted with impact craters and dust left from collisions and other object in the solar system.
Why does the composition of asteroids in the asteroid belt vary with distance from the sun?
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