Comets, Asteroids and Meteor Notes
Comets, Asteroids and Meteor Notes
Comets, Asteroids and Meteor Notes
Comets (a.k.a. Dirty Snowball) - comes from the Greek word meaning "hair.”
loose collections of ice, dust, and small rocky particles whose orbits are usually very long, narrow ellipses.
A Comet’s Head
– Outer layer= Coma (water vapor, CO2, and other gases)
– Solid inner core= Nucleus (frozen ice, silicate, gas and dust )
Silicates - minerals that contain the elements silicon, oxygen, and at least one metal
Comet’s Tail - gas (ion) tail and dust tail
Scientists also discovered a faint sodium tail, a third type of comet tail to add to the well-known dust and plasma (or ion)
tails.
When does a comet gets its tail?
• As a comet approaches the sun heats up, some of its gas and dust stream outward, forming a tail.
• A comet’s tail can be more than 100 million kilometers long.
Why does the tail of a comet point away from the sun? Answer: Tails point away from the sun because of the force of the solar wind.
Origin of Comets
Kuiper belt-doughnut - shaped region that extends beyond Neptune’s orbit to about 100 times Earth’s distance from the sun.
• Oort cloud - spherical region of comets that surrounds the solar system out to more than 1,000 times the distance between
Pluto and the sun.
2 Types of Comets
1. Short-period comets - come from Kuiper Belt and take less than 200 years to complete an orbit around the Sun.
2. Long-period comets - come from the Oort Cloud and take more than 200 years to complete an orbit around the Sun.
Famous Comets
1. Comet Halley - the most famous comet in history. It reappears every 76 years. Its next appearance is in 2061.
2. Comet Hale-Bopp - exceptionally large size
July 23, 1995- an unusually large and bright comet was seen outside of Jupiter's orbit by Alan Hale of New Mexico and
Thomas Bopp of Arizona. It will not appear again for another 2,400 years.
It was visible even through bright city skies, and may have been the most viewed comet in recorded history.
3. Comet Hyakutake-On January 30, 1996, Yuji Hyakutake (pronounced "hyah-koo-tah-kay"), an amateur astronomer
from southern Japan, discovered a new comet using a pair of binoculars.
4. Comet Shoemaker-Levy 9-Between July 16 and July 22, 1994, more than 20 fragments of Comet Shoemaker-Levy
9 collided with the planet Jupiter. Astronomers Carolyn and Eugene Shoemaker and David Levy discovered the
comet in 1993. It was the first collision of two Solar System bodies ever to be recorded.
METEOROID, METEOR & METEORITE
Meteor – a light phenomenon or a streak of light that occurs when a meteoroid burns up as it enters the Earth’s
atmosphere. Also called as “shooting star” or “falling star”
Meteoroid – a broken up rock and dust from either a comet, asteroid, the moon or from Mars.
- it can be as small as a grain of sand or as big as a boulder.
When it enters Earth’s atmosphere, the air in front of the meteoroid heats up, causing the materials to burn up.
From Earth, these glowing materials appear as a streak of light or a fast-moving bright object that appears to have a tail just
like a comet.
Meteorite -meteoroids that pass through the atmosphere and hit Earth’s surface.
Meteorites are of importance to scientist in studying the occurrence of different elements and compounds on Earth.
Classifications of Meteorite
1. Stony – made of rock, but can also contain small amounts of iron. Types: Chondrites and Achondrites
2. Stony-iron – formed by mixing between metal cores and the rocky magmas within asteroids.
- they are extremely rare. Types: Pallasites and Mesosiderites
3. Iron - made up of pure nickel and iron metal with some impurities such as graphite and the mineral troilite which
may have originated from within the metallic cores of asteroids.
Iron meteorites fall very rarely, but are easier to find because they can survive re-entry relatively intact, are
very resistant to weathering and look very different to normal rocks.
The largest meteorites ever discovered.
Ancient cultures used to use metal from these iron meteorites to make tools and jewelry.