Asteroids are small, rocky objects that orbit the sun. Although asteroids orbit the sun like planets, they are much smaller than planets.
There are millions of asteroids, ranging in size from hundreds of miles to several feet across. In total, the mass of all the asteroids is less than that of Earth’s moon.
Despite their size, asteroids can be dangerous. Many have hit Earth in the past, and more will crash into our planet in the future. That’s one reason scientists study asteroids and are eager to learn more about their numbers, orbits, and physical characteristics. If an asteroid is headed our way, we want to know that.
Location
The majority of known asteroids are in the asteroid belt, a large donut-shaped ring located between the orbits of Mars and Jupiter, and orbit approximately 2 to 4 AU (186 million to 370 million miles/300 million to 600 million kilometers) from the sun.
Where did asteroids come from?
Asteroids are leftover from the formation of our solar system. Our solar system began about 4.6 billion years ago when a big cloud of gas and dust collapsed. When this happened, most of the material fell to the center of the cloud and formed the sun.
Some of the condensing duct in the cloud became planets. The objects in the asteroid belt never had the chance to be incorporated into planets. They are leftovers from that time long ago when planets formed.
7 Cool Science Experiments For Kids To Do At HomeWhat is the difference between an asteroid and a comet?
The main difference between asteroids and comets is their composition, as in, what they are made of. Asteroids are made up of metals and rocky material, while comets are made up of ice, dust and rocky material. Both asteroids and comets were formed early in the history of the solar system about 4.5 billion years ago. Asteroids formed much closer to the Sun, where it was too warm for ices to remain solid. Comets formed farther from the Sun where ices would not melt. Comets that approach the Sun lose material with each orbit because some of their ice melts and vaporizes to form a tail.
Asteroids Encounter With Earth
Asteroids that fall into the category of Near Earth Objects have orbits that bring them in close proximity with our planet, and a number of notable impact sites have been attributed to asteroids. Most famously, the Chicxulub crater under the Yucatán Peninsula in Mexico is the result of an asteroid impact that might have wiped out the dinosaurs. Another asteroid known as Tunguska didn’t impact Earth but exploded a few miles above the Podkamennaya Tunguska River on June 30, 1908. A similar explosion made headline news in 2013 when the near-Earth asteroid dubbed Chelyabinsk exploded in air blast that left 1,500 Russians seeking medical attention.
Why Does The Tower Of Pisa Lean?What is the largest asteroid?
The largest asteroid is called Ceres. It is about one-quarter the size of the moon and orbits the sun between Mars and Jupiter in a region called the asteroid belt. Unlike most asteroids, Ceres is spherical in shape. Ceres was discovered by the Italian astronomer Giuseppe Piazzi in 1801 as he searched for a planet that was predicted to exist between Mars and Jupiter. It was the first asteroid ever discovered. It is a dwarf planet.
Some facts about Asteroids
1. Most are Found in One Area
Of the millions of asteroids that inhabit our solar system, a majority can be found in a region between the orbits of Mars and Jupiter. This region is called the Asteroid Belt.
2. A meteoroid (a piece of an asteroid) the size of a car falls into the Earth’s atmosphere on average once every year.
This creates a bright fireball effect, but it usually burns up in the atmosphere before it reaches the ground.
3. Asteroids have moons.
While we think of moons as something that orbits a planet, asteroids also have smaller bodies that orbit them! The first known one was Dactyl, which was discovered in 1993 to be orbiting a larger asteroid called Ida. More than 150 asteroids are known to have moons, with more being discovered periodically. A more recent example is one discovered orbiting Asteroid 2004 BL86, which passed 750,000 miles (1.2 million kilometers) from Earth in early 2015.
15 Mind-Blowing Facts About Human Nature4. Mission to a metal world.
NASA’s Psyche mission will launch in 2022 to explore an all-metal asteroid—what could be the core of an early planet—for the very first time. And in October 2021, the Lucy mission will be the first to visit Jupiter’s swarms of Trojan asteroids.
5. They were Created at the Same Time as the Earth
Many astronomers believe that asteroids are rocky leftovers from the formation of the Solar System 4.6 billion years ago. One theory is that after the Big Bang, dust particles came together to form celestial objects through a process called accretion – smaller objects came together with other small objects, creating larger space rocks. Some of these celestial rocks were able to grow large enough to develop their own gravity and became planets. Many others were held back from getting together by Jupiter’s gravitation force. These became asteroids.
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