The Ancient Matter Of Asteroids

Asteroids Have Long Fascinated Us

Have you ever wanted to discover more about asteroids? These rocky objects which orbit the Sun are frequently mentioned in the news, with sightings of expected ‘near’ approaches to Earth eagerly tracked by scientists. You may wonder what asteroids are and where they come from. And even how you can track them, if you’re an eager stargazer. This article helps to get you started.

What Is An Asteroid?

They are small rocky objects which orbit the Sun, believed to be amongst the most ancient matter in our solar system, the result of its early formation about 4.6 billion years ago. By comparison, most dinosaurs became extinct 65 million years ago, which itself is often attributed to an asteroid strike, specifically a six-mile-wide asteroid called Chicxulub, which went hurtling into the sea off the east coast of what is now Mexico.

Where Can They Be Found?

Most reside in the aptly named asteroid belt, which is a region of space populated by millions of asteroids, located between the inner and outer planets. The main belt is situated between Mars’s and Jupiter’s orbits.

What Are They Made Of?

According to NASA, asteroids are believed to be dark in appearance and made of clay and silicate rocks. They have been classified into three types:

• C-Type (carbonaceous) asteroids. These make up the majority of asteroids and are in the outer belt.
• S-type. The Bright S (silicaceous) asteroids in the inner belt.
• M-type. Metallic asteroids situated in the middle of the asteroid belt and mostly made up of metallic iron.

How Is An Asteroid Different From A Meteor?

A meteor is the result of a small piece of an asteroid or comet, called a meteoroid, burning up upon entering Earth’s atmosphere. If a piece of a meteoroid manages to hit the earth without burning up entirely, the piece that remains after doeing so is called a meteorite. There is an article on meteors and meteorites which you can also read on our site here.

Can Asteroids Be Seen With The Naked Eye?

Asteroids reflect sunlight just like the planets do, which means that yes, if you have a suitable telescope then you can observe them from Earth.

How Many Asteroids Are There?

According to NASA, the main asteroid belt is estimated to contain between 1.1 and 1.9 million asteroids larger than 1 kilometer (0.6 miles) in diameter, and millions of smaller ones.

Are There Any Near Earth?

According to online sources, there are believed to be over 30,503 known near-Earth asteroids (NEAs).

Do We Have Any Coming Close to Earth?

The most recent asteroid pass was by one named 2023 LZ, which flew inside the moon’s orbit on the 14th of June this year. It had a span of about 10 to 32 metres and at its nearest point was about 197,000 miles (317,000 km) from Earth’s surface, which was considered relatively close. In truth, we can only see how close an asteroid is as our current technology can allow – we can see a lot from a distance, but not all. When considering the speed at which they travel and that there are so many of them to watch, this question is a difficult one to answer.

What Are The Largest Asteroids In Our Solar System?

In order, the largest are believed to be Ceres, Vesta, Pallas, Hygiea and Interamnia. Ceres is 583.7 miles and was first discovered by Giuseppe Piazzi on January 1, 1801 and was named in honour of the Roman goddess of agriculture. The top four make up about half of the mass of the entire asteroid belt.

Can An Asteroid Become A Dwarf Planet?

This has happened. For example, Ceres was classed as an asteroid but is very different and so much bigger from nearby asteroids that it was given classification as a dwarf planet in 2006 by scientists. Other dwarf planets include Pluto, Eris and Makemake.

If you’d like to find out more, The NASA website has an excellent asteroid tracker ‘Eyes on Asteroids’ for avid space watchers. You can learn more about asteroids and check the ‘Asteroid Watch’ section which shows which asteroids will have the closest approaches to Earth.