Most meteors that enter the Earth's atmosphere are pieces of asteroids from the asteroid belt. The meteors were formed more than 4 billion years ago during what is thought to be the early stages of the solar system.
A comet is a frozen collection of rocks, gases and dust that orbits around the sun, while a meteor is a piece of debris that comes into contact with a planet's atmosphere. Before it collides with a planet, a meteor is called a meteoroid.
The burning meteor that causes a shooting star can vary from the size of a grain of sand to a 1-meter-long object. As the meteor falls through the atmosphere, it burns up and gives the appearance of a star falling.
Though stars are shining in the sky at all times, they are not visible during the day because the sun's brightness overpowers the dimmer stars. At night, without interference from the sun's rays, the other stars become visible.
Giuseppe Piazzi discovered the first and largest asteroid, Ceres, on Jan. 1, 1801, while mapping stars. He found it orbiting in an area between Mars and Jupiter. Measuring 583 miles across, this almost spherical asteroid contains about one-fourth of the mass of all known asteroids.
Halley's comet has a mean diameter of 11 kilometers across. On average, it passes by Earth between every 75 to 76 years. In 1910, Halley's comet came as close as 13.9 million miles.
Comets are made up of collections of ice, dust and rocky particles that are leftover from the formation of the solar system 4.6 billion years ago. Comets range in length from a few kilometers to tens of kilometers. The nuclei are comprised of frozen gases such as carbon dioxide, carbon monoxide, methane and ammonia.
A meteor is defined as a piece of material that passes through Earth’s atmosphere. While it is traveling through space and before it enters the atmosphere, a meteor is called a meteoroid.
The comet people are most likely to know by name, and therefore perhaps the most famous, is Halley's Comet. This comet can be seen from Earth's about every 75 years, with its next predicted return in 2061.
Dozens of asteroids orbit throughout the galaxy, but the most famous are those that have impacted the Earth. Asteroids that do are best known by the major craters they leave behind. The Vredefort crater was created by an asteroid nearly two billion years ago in South Africa. The crater has a radius of 118 miles and is believed to be the largest asteroid crater.
According to the Center for Meteorite Studies at the Arizona State University, meteorites are believed to come from the asteroid belt between Mars and Jupiter. Hubblesite defines a meteorite as a meteor or a piece of meteor that makes it through the atmosphere and lands on earth.
The average speed of an asteroid is 25 kilometers per second. Depending upon the size and velocity of an asteroid, a collision with Earth could have catastrophic effects.
Meteors burn up in the mesosphere when they encounter the molecules from that layer and rub up against them. This generates heat; ironically, the mesosphere is the coldest part of the atmosphere.
Asteroids are formed from the leftovers of the formation of our solar system from about 4.6 billion years ago. Early on, the birth of Jupiter prevented any planetary bodies from forming in the gap between Mars and Jupiter, causing the small objects that were there to collide with each other and fragment into the asteroids seen today.
Recent sightings of great comets, or comets bright enough to be seen without the aid of special equipment, are Comet Lovejoy in 2011, Comet McNaught in 2007, Comet Hale-Bopp in 1997, Comet Hyakutake in 1996, Comet West in 1976, Comet Ikeya-Seki in 1965, Comet Skjellerup-Maristany in 1927 and Halley's Comet in 1910. Numerous comets too dim to be seen by anyone but astronomers regularly pass through the solar system.
Meteors falling through the atmosphere, called shooting stars, occur regularly and are seen on any clear night every 10 to 15 minutes. Shooting stars occur reliably and in large numbers during the meteor showers that occur yearly based on the passage of particular comets or minor planets close to Earth.
The bright green color of some meteorites is caused by the internal combustion of metals as they pass through the upper atmosphere. Many asteroids are rich in nickel and have trace amounts of copper. Both metals burn green when sufficiently heated.
Edmond Halley was not the first scientist to observe Halley's Comet, but he discovered that recorded comet sightings in 1531, 1607 and 1682 were part of a recurring orbital cycle, according to Encyclopaedia Britannica. He published his findings in 1705 and correctly predicted the comet's next appearance in 1758.
Ukrainian scientists discovered a large asteroid in late 2013 that could possibly strike the Earth on Aug. 26, 2032. If such a collision occurred, it would strike with a force 50 times greater than the largest atomic bomb.
Cosmic rays are fast-moving elementary particles, such as protons, electrons and atomic nuclei, that strike the Earth from outer space. They travel almost at the speed of light. Scientists believe they originate from supernovas, black holes and quasars.
Meteors from Mars arrive on Earth as the result of impacts on the planet by other bodies, which launch material out into space. Some of this debris is pulled in by the gravity of the Earth, falling as Martian meteorites.