23.4 - minor members of the solar system

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Do Now What is the difference between asteroids and meteoroids?

Do Now What is the difference between asteroids and meteoroids? Asteroids are much larger in size and can cause more destruction.

Key Words Proximity Contribute Extraterrestrial

Asteroid Coma Comet Meteor Meteorite Meteoroid Vocab Words

Minor Members of the Solar System Asteroids Meteoroids Comets

Asteroids

Asteroids Microplanets Small rocky bodies that have been likened to “flying mountains.” The largest, Ceres, is about 1000 kilometers in diameter, but most are only about 1 kilometer across. The smallest asteroids are assumed to be no larger than a grain of sand.

Asteroids Most asteroids lie between the orbits of Mars and Jupiter. They have orbital periods of 3-6 years. Some asteroids have eccentric orbits and travel very close to the sun, others regularly pass the Earth and the moon. Most of recent impact craters on the moon have been from asteroids, and if Earth were to encounter an asteroid, would be possible for it to be a global killer.

Asteroids Most asteroids have irregular shapes and scientists think this is because there could have been a planet orbiting the sun in between Mars and Jupiter that broke apart. But if you were total the mass of the asteroids, they would equal 1/1000 that of Earth and would of not been a large planet. No conclusive evidence though to prove where the asteroid belt came from.

Comets

Comets Comets are among the most interesting and unpredictable bodies in the solar system. Comets are pieces of rocky and metallic materials held together by frozen gases, such as water, ammonia, methane, carbon dioxide and carbon monoxide.

Comets Many comets travel in very elongated orbits that carry them far beyond Pluto. Takes hundreds of thousands of years to complete a single orbit around the sun. Some are much less and we can see pass by more often. The tail of a comet always points away from the sun.

Coma The glowing head of a comet. A small glowing nucleus with a diameter of only a few kilometers can sometimes be detected within a coma. As comets approach the sun, some, but not all, develop a tail that extends for millions of kilometers.

Kuiper Belt Comets orbit in the Kuiper belt, which is beyond Neptune. They will orbit there unless there is a collision in the Kuiper belt to send a comet towards the inner solar system or by the gravitational pull by one of the Jovian planets.

Halley’s Comet The most famous comet known to Earth. Has a short-period orbit of about every 76 years. First discovered in 1705 by English astronomer, Edmond Halley. In 1986 we were able to get a probe close enough to Halley’s comet to examine the coma and discovered that the nucleus is a potato shape, 16 kilometers by 8 kilometers. The surface is irregular and full of crater like pits. Next perihelion – July 28 2061 Next aphelion – December 9 2023

Meteoroids

Meteoroids These are better known as “shooting stars.” Created when a meteoroid enters Earth’s atmosphere. A meteoroid is a small solid particle that travels through space.

Meteoroids Most of them originate from any of the three following sources: Interplanetary debris that was not gravitationally swept up by the planets during the formation of the solar system. Material from the asteroid belt. The solid remains of comets that once traveled near Earth’s orbit. A few meteoroids are believed to be fragments of the moon, or possibly Mars, that were ejected when an asteroid impacted their bodies.

Meteoroids Some are as large as asteroids. Most are the size of a grain of sand. Most vaporize before reaching Earth's surface. Those that do enter Earth's atmosphere and burn up are called meteors. These are called “shooting stars” and it is the light that we see that is caused by friction between the particle and air, which produces heat. Meteor showers, are swarms of meteors entering and burning up in Earth's atmosphere.

Meteoroids A meteoroid that actually reaches Earth's surface is called a meteorite. Prior to moon rocks being brought back, meteorites were the only extraterrestrial materials that could be directly examined. They helped us understand the age of the solar system and found that the oldest meteorites were approximately 4.54 billion years old. A few very large meteorites have blasted out craters on Earth's surface. For example the most famous, Meteor Crater in Arizona.

Group Activity Compare meteors, meteorites and meteoroids.