Asteroids: Sam Levy

Asteroids are metallic, rocky bodies without atmospheres that orbit the Sun. But too small to be classified as planets. 

This is a photo of the asteroid Ida. 

Tens of thousands of asteroids are in the main asteroid belt located between the orbits of Mars and Jupiter.

This photo is a census on near-Earth astroids. 

Most asteroids fall into 3 categories: Carbonaceous, Metallic, and Siliceous.

Albedo:

The fraction of the total light striking a surface that gets reflected from that surface. An object that has a high albedo (near 1) is very bright; an object that has a low albedo (near 0) is dark. The Earth's albedo is about 0.37 and the Moon's is about 0.12.

Carbonaceous asteroids make up 75% of all known asteroids. Very dark with an albedo of 0.03-0.09. Composition is thought to be similar to the Sun, depleted in hydrogen, helium, and other volatiles. They consist of clay and silicate rocks. To see the biggest C-type asteroid requires a small telescope. They exist furthest from the Sun, and so have been least altered by heat, meaning that they are the most ancient. Due to the fact that some have never even reached temperatures above 50°C, it is estimated they can contain up to 22% water.

Siliceous asteroids accounts for about 17% of known asteroids. They are made up primarily iron and nickel with iron and magnesium silicates added.  They inhabit the inner Asteroid Belt. S-types are moderately bright with an albedo of 0.10 to 0.22. The largest S-type asteroids are visible in 10x50 binoculars.

Metallic asteroids includes many of the rest of the known asteroids. These are made up mostly of nickel-iron, and are found in the middle region of the Asteroid Belt. 21 Lutetia was the first M-type asteroid to be imaged by a spacecraft. This happened on July 10, 2010. 

The asteroid that killed the dinosaurs would have killed them in several waves. The first one would have been the initial impact and the resulting tsunami. The next wave would have been acid rain and fires that would have destroyed the plant life. The third wave would have been the herbivores, followed by the meat eaters, then finally the the carrion eaters would have died of starvation. Eventually 90% of the life within thousands of miles would have been dead. The asteroid that killed the dinosaurs 65 million years ago was initially discovered by Glen Penfield in the 1970′s while he was searching for oil in the area. The asteroid that killed the dinosaurs was the Chicxulub asteroid in the Yucatan Peninsula, Mexico. The Chicxulub Crater is approximately 180 km  in diameter and 10 km deep. The Chicxulub Crater was formed by an asteroid that was about 10 km in diameter and it hit with 100 million megatons of force. The evidence that Alan Hildebrand finally submitted for approval included: shocked quartz, tektites, and a magnetic anomaly in the area.

The formation of Jupiter brought the end to the formation of planetary bodies between Mars and Jupiter. This caused the material that was in the area to collide with each other, breaking up into the asteroids we know today. Because the asteroids have remained mostly unchanged for billions of years, studies of them could tell us a lot about the early solar system.

A meteoroid is a small piece from a comet or asteroid.

A meteor is the visible streak of light that comes from a meteoroid.

A meteorite is a meteoroid that survives impact with the Earth's surface.

An asteroid that passed by Earth recently was 2013 ET. This asteroid passed by the Earth on March 9th. It was about 600,000 miles away from us, which is 2.5 times farther away than our moon. It is believed to be 210 ft by 460 ft. It was moving at a speed of about 26,000 miles per hour. At this speed this could have destroyed a whole city if it hit Earth.

A shooting star is actually meteor. This is a chunk of extraterrestrial rock pulled into the Earth's atmosphere by gravity. They are usually the size of dust or sand. While the small chunk of extraterrestrial rock is going through Earth's atmosphere it begins to build-up frictional heat. This causes the rock or particle to brightly glow as they continue to burn and fall into Earth's atmosphere. This is why people call them shooting stars. Since on the surface it looks like a star is moving or shooting across the night sky.