Small Bodies in The Solar System PDF

SMALL BODIES IN THE SOLAR SYSTEM COMETS Like asteroids, comets are suspected to be remnants of planet formation in the Solar System about 4.6 billion years ago. But while asteroids are generally comprised of rock and metal, comets are more akin to dirty snowballs. They are composed of frozen...

SMALL BODIES IN THE SOLAR SYSTEM COMETS Like asteroids, comets are suspected to be remnants of planet formation in the Solar System about 4.6 billion years ago. But while asteroids are generally comprised of rock and metal, comets are more akin to dirty snowballs. They are composed of frozen gases such as carbon dioxide, methane, and ammonia, as well as water ice, in which dust particles and rocky material are embedded. As a comet approaches the Sun, solar radiation "melts" the surface, vaporizing molecules of gas and dust and creating the brilliant tail comets are best known for. A comet's tail will always point away from the Sun, which means it doesn't always trail behind the comet on its journey, but rather can travel beside or in front of it.  WHERE DO THEY COME FROM? Comets spend most of their lives far away from the Sun in the distant reaches of the solar system. They primarily originate from two regions: the Kuiper Belt, and the Oort Cloud. The Kuiper Belt is a disk composed mainly of icy bodies that stretches from about Neptune's orbit (around 30 AU from the Sun on average) out to about 50 AU from the Sun. The Oort Cloud is at the edges of the Sun's gravitational influence (about 50,000 to 200,000 AU) and divided into two regions: the inner, disc-like Hills cloud, and the outer spherical cloud, both composed of icy bodies. Short-period comets, which orbit the Sun in 200 years or less, are usually Kuiper Belt objects, while long- period comets that take hundreds or thousands of years to orbit the Sun  Parts of a comet When they are near the Sun and active, comets have several distinct parts: nucleus: relatively solid and stable, mostly ice and gas with a small amount of dust and other solids; coma: dense cloud of water, carbon dioxide and other neutral gases sublimed from the nucleus; dust tail: up to 10 million km long composed of dust particles driven off the nucleus by escaping gases; ion tail: as much as several hundred million km long composed of plasma and laced with rays and streamers caused by interactions with the solar wind Comets represent some of the oldest, basically untouched objects in the solar system. Their very composition seems to represent the original makeup of the vast nebula that ultimately condensed to form the sun and planets. Comets orbit the Sun in VERY elliptical paths The tail always points away from the Sun!  ASTEROIDS Asteroids are rocky and metallic objects that orbit the Sun but are too small to be considered planets. They are known as minor planets. Asteroids are material left over from the formation of the solar system.  Meteoroids A meteoroid is matter (stony or metallic) revolving around the sun that is too small to be called an asteroid or a comet. A meteorite is a meteoroid that reaches the surface of the Earth without being completely vaporized. This streak of light in the sky is known as a meteor. Meteoroids – interplanetary rocky material smaller than 100m (down to grain size). called a meteor as it burns in the Earth’s atmosphere if it makes it to the ground, it is a meteorite Most meteor showers are the result of the Earth passing through the orbit of a comet which has left debris along its path  Oort Cloud The Oort cloud is an immense spherical cloud surrounding the planetary system and extending approximately 2-3 light years, about 30 trillion kilometers from the Sun. This vast distance is considered the edge of the Sun's orb of physical, gravitational, or dynamical influence  Kuiper Belt a region of the Solar System that exists beyond the eight major planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, in that it contains many small bodies, all remnants from the Solar System’s formation. But unlike the Asteroid Belt, it is much larger – 20 times as wide and 20 to 200 times as massive. https://www.youtube.com/watch?v=XjW6k--6Oi0#t=229