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Vagabonds of the Solar System
Asteroids, Comets, and Meteoroids
A search for a planet between Mars and Jupiter led to the discovery of asteroids
• Thousands of asteroids with diameters ranging from a few kilometers up to 1000 kilometers.
• Most orbit within the asteroid belt between the orbits of Mars and Jupiter
• Asteroids are small chunks of ROCK or Metal that revolve around the sun..
The asteroids are the relics of planetesimalsthat failed to accrete into a full-sized planet, thanks to
the gravitational effects of Jupiter and other Mars-sized objects.
The sun and Jupiter are keeping the asteroids in balance because both are pulling in opposite directions.
Jupiter’s gravity helped shape the asteroid belt
Often asteroids become CAPTURED because a planet’s gravity pulls them in orbit.
Jupiter’s gravity captures asteroids in two locations, called Lagrangian points, along Jupiter’s orbit
Asteroids occasionally collide with one another,
• causing them to break up into smaller fragments
Asteroids are found outside the asteroid belt—and have struck the Earth
• These outside belt asteroids, called near-Earth objects, move in highly elliptical orbits that cross the path of Mars and Earth
• If such an asteroid strikes the Earth, it forms an impact crater whose diameter depends on both the mass and the speed of the asteroid
An asteroid may have struck the Earth 65 million years ago, possibly causing the extinction of the dinosaurs
and many other species
Comets are a mixture of ice, dust, and a small amount of rock in the form of a sphere.
Comets move around the sun in highly elliptical orbits.
Comets are hard to find unless they are near the SUN because…
• As they approach the sun, the entire comet vaporizes (Sublimes).
• The temperature increases due to the suns solar radiation.
• The nucleus of ice vaporizes (Solid to a Gas).
• Solar winds push the gas and dust away to form dust and ion tail.
PARTS of a COMET
NUCLUES: Center of a comet made of ice, gas, and dust
COMA: Thick envelope of water, CO2, and dust that melts/sublimes out of the nucleus.
DUST TAIL: Solid rocky particles being pushed away by the sun’s solar wind.
ION TAIL: Frozen CO2 being vaporized and pushed away by the sun’s solar wind.
An ion tail and a dust tail extend from the comet, pushed away from the Sun by the solar wind and radiation pressure
Comets formed from left over material during the formation of the solar system.
• Most comets are found in the Kuiper belt beyond Pluto.
• The Kuiper Belt is part of a vast cloud in near interstelar space called the Oort Cloud.
Halley’s Comet – pt.1 (SD)
Comets eventually break apart, and their fragments give rise to meteor showers
When Earth passes through the tail of a comet, this is when we typically see
“Shooting Stars”
Small rocks in space are called meteoroids Meteoroids:
– A meteoroid is a chunk of rock that is smaller than an Asteroid.
– Average about 100 m in diameter.
– It is part of an asteroid or left over from comet debris.
– Revolves around the sun
– Located outside Earth’s atmosphere.
Meteors – When a meteoroid comes into contact with Earth’s Atmosphere.
• Meteors burns up due to the intense friction of Earth’s Atmosphere.
• We see a shooting star in the sky when this occurs.
Meteorites are meteoroids that go through the entire atmosphere without burning up completely, making landfall.(A meteor that makes it through the atmosphere)
Meteorites cause craters on Earth Surface
Meteorites are classified as stones, stony irons,or irons, depending on their composition
Irons and stony irons are fragments of the core of an asteroid that was large enough and hot enough to have undergone
chemical differentiation, just like a terrestrial planet
Some meteorites retain traces of the early solar system
• Some stony meteorites come from the crust of such differentiated meteorites, while others are fragments of small asteroids that never underwent differentiation
• Rare stony meteorites called carbonaceous chondrites may be relatively unmodified material from the solar nebula
• These meteorites often contain organic material and may have played a role in the origin of life on Earth
• Analysis of isotopes in certain meteorites suggests that a nearby supernova may have triggered the formation of the solar system 4.56 billion years ago
• Fragments of “burned out” comets produce meteoritic swarms
• A meteor shower is seen when the Earth passes through a meteoritic swarm
