Asteroids are essentially remnants of the primitive building blocks that created the terrestrial planets in our solar system. Scientists believe that asteroids have not changed very much since the time they were formed, making them cosmic time capsules that can reveal how planets like our own world formed.In addition, asteroids are thought to contain organic molecules like amino acids—the basis for proteins and DNA—leading to speculation that a meteorite from an asteroid could have seeded the early Earth with the building blocks of life.Despite what Hollywood movies may lead us to believe, the risk of a collision between an asteroid and Earth is extremely small. NASA's Center for Near-Earth Object Studies regularly monitors the orbits of near-Earth asteroids and calculates their risk of impact within the next 100 years.
What are they? Asteroids are small rocky or metallic bodies that orbit the Sun. They can range in size from less than 1 cm to hundreds of kilometres. Some asteroids have their own moons. Asteroids are leftovers from the formation of our solar system 4.6 billion years ago. What are they made of? They are made of rock, metals, and other materials. Some even contain water! There are three common types: Carbon-rich, rocky, and metallic. Carbon-rich asteroids are dark, contain carbon, and look like charcoal. Rocky asteroids have a stony texture, contain silicate materials and iron, and look like dark rocks. Metallic asteroids have a shiny appearance, contain nickel and iron, and look like steel. Where are they? Near-Earth asteroids are located 150 million km from the Sun. Most asteroids are located in the Main Belt, between Mars and Jupiter, 330 to 480 million km from the Sun. Why do we study them? We study asteroids to learn what types of materials existed billions of years ago in order to understand the formation and evolution of the planets. Some of the material trapped inside asteroids might be the building blocks of life.
Credit: Canadian Space Agency

DARK SKIES: Asteroid, meteor - what's the difference?

ON ANY night of any week, you will see a ‘shooting star’, which is actually a meteor – tiny grains of space dust burning up from friction through the atmosphere.

When they land on Earth they are called meteorites and in some cases are quite large, up to a few metres in size and weighing up to two tonnes.

Of all the meteors we see, however, 99 per cent burn up and fall to Earth as dust.

Back in 1984, a meteor dubbed ‘Alanhills 84’ was found to be a piece of Mars rock blasted into space by a meteor striking the Martian surface.

About a dozen times a year our planet passes through the tails of small comets that regularly orbit the Sun.

As we pass through those dusty tails, hundreds of tiny particles enter and burn into the atmosphere and we see them as a ‘meteor shower’.

Unfortunately, due to our southern latitudes, those events are not as spectacular as those in the north. Back in pagan times, however, meteors were thought to be omens of doom and gloom, while lightning and thunder were the anger and revenge of the gods, and comets were the death of kings.

Asteroids, on the other hand, are something else. The most famous of all was the one that ploughed into the Bay of Mexico 65 million years ago. The crater, named Chicxulub – ‘The Fire of the Beast’ – is seen from space and about 1200km in diameter.

The size of the asteroid is estimated to have been 10-15km in diameter, and from its fiery entry through the atmosphere it heated the air and depleted the oxygen, which caused many lung-breathing species to suffocate, and the wall of water as this rock struck the water, estimated to be 2-3km tall, swept away all living things, including dinosaurs.

When the asteroid made contact with the seabed 3000m below, the explosion is estimated to have had a nuclear force of 100 billion nuclear bombs.

The asteroid explosion created a dust cloud that surrounded the Earth, blocking out the Sun and creating a nuclear winter.

Astrophysicists and geophysicists say if Earth was to be whacked by a similar size or larger asteroid, striking ocean or land, half of the world’s population and animals would be wiped out.

Could we blow it up in space with a nuclear warhead?

No. If we did, billions of radioactive bits of rock would rain down on us, creating a deadly radioactive environment and life on this planet would be no more.

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Brandon Corvis
Brandon Corvis
Bran writes mostly on science and is an avid reader and writer of popular science. He brings sciency a literetic emphasis bring it to mainstream media for all.

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