What You Need to Know About Comets and Asteroids

At the beginning of our solar system’s creation, a massive billowing cloud of dust and gas circled around the Sun, and dust particles collided with each other and formed into a rock until they ultimately reached the size of a boulder. This process formed the planets of our solar system and tens of thousands of comets and asteroids.

Comets and asteroids have been the basis of knowledge about the conditions of the early solar system. Studying them reveals secrets about our origins and the events that led to our world’s creation, and they might even provide clues on where the materials that made life possible on Earth originated.

The National Aeronautics and Space Administration, commonly known as NASA, deploys robotic spacecraft used to visit comets and asteroids to bring back samples that could be studied to figure out the whats and hows of these space rubbles.



Around 4.6 billion years ago, from the early formation of our solar system, rocky remains were left out, and those were called Asteroids. Currently, there are around 1 035 651 known Asteroids.

Most of the asteroids can be found within the central asteroid belt. These asteroids mainly orbit the Sun between planet Mars and Jupiter. Asteroids have different sizes ranging from about 329 miles or 530 kilometers in diameter to less than 33 feet or 10 meters across. 

When combined, the total mass of all the asteroids is less than that of the Moon.

Asteroids are mostly irregularly shaped, with a few of them being spherical. Most of these space rubbles are dented and cratered. Asteroids also revolve around the Sun the same way as planets in elliptical orbits, but their rotation is somewhat erratic, and they tumble as they go. 

There are currently 150 known asteroids with a small moon accompanying them, while some even have two moons.

Asteroids are classified into three broad compositions: C-, S-, and M-types. The C-type or chondrite asteroids are most common and are made of silicate rocks and clay. These asteroids also have a dark appearance. They are one of the most ancient objects in the solar system. 

The S-types or the stony asteroids are made up of nickel-iron and silicate materials. The last classification, the M-types, are metallic and made up of nickel-iron. The differences in the asteroids’ compositions are related to how far away they were from the Sun when they were formed.

the Sun, the planets, space, stars, asteroid belt

Asteroid Belt

Asteroids are small bits of rock with diameters ranging from a few feet to many miles (meteoroids refer to minor asteroids). Ceres, the enormous asteroid, is around 590 miles wide (950 kilometers). It is located in the asteroid belt between Jupiter and Mars, like other asteroids.

Because of Jupiter’s gravitational influence, many astronomers think the belt is primordial material, which never glommed into a planet. Other scientists believe the belt is the remains of a planet that was shattered following a collision.


Comets have been referred to as “dirty snowballs” as they consist primarily of ice and are coated with dark organic material. They are the leftovers from the creation of our solar system around 4.6 billion years ago. There are currently 3,694 known comets. 

Astronomers think that comets may carry essential clues about our solar system formation and thought they might have brought the building blocks of life to Earth and other parts of our solar system. In the past, when not much was known about comets, people were amazed and frightened as they viewed comets as long-haired stars that appeared unpredictably in the sky.

In 1951 according to Gerard Kuiper, comets were theorized to have come from Pluto’s realm just beyond Neptune, where a disc-like belt of icy bodies existed, and a population of dark comets orbits the Sun. From time to time, the icy objects are pushed by gravity into orbits that bring them closer to the Sun. These objects become what we call the short-period comets, and they take less than 200 years to orbit the Sun, making their appearances predictable as they have passed by before. 

Long-period comets, however, are less predictable and many of them arrive from the Oort Cloud: a region about 100,000 astronomical units away from the Sun. These types of comets take as long as 30 million years to complete just one trip around the Sun.

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Comets have something called a nucleus. They are a tiny frozen part and are often no larger than a few kilometers. They have icy chunks and frozen gases that have fragments of embedded dust. As a comet nears the Sun, it warms up and develops an atmosphere or a coma. 

Due to the Sun’s heat, the comet’s ices change to gases, making the coma larger. A comet’s coma may reach up to hundreds of thousands of kilometers. Comets have two tails: an ion tail and a dust tail. The bright tails are formed from the pressure of sunlight and the high-speed solar wind that blows the coma dust and gas away from the Sun.

While there are likely billions of comets circling the solar system’s outskirts, brilliant comets only arrive once every decade in Earth’s visible night sky. Comets with short periods, such as Halley’s, are disrupted by the Kuiper belt beyond Neptune’s orbit and travel through the inner solar system either once twice in a human lifetime. Long-period comets originate in the Oort Cloud, which encircles the solar system’s far reaches, and pass close to the Sun once in every hundred or thousands of years.

How Asteroids and Comets Get Their Names

When it comes to naming asteroids, the International Astronomical Union’s Committee on Small Body Nomenclature is tasked to do it. They are a little less strict in naming Asteroids than other IAU naming committees. The asteroid can be named after pets, a rock musician, beloved teachers, and a more somber tribute for the space crew killed last 2003. 

Asteroids are also named after places and various other things, while some are given a number. Comet naming, however, is mainly named after their discoverer, which is either a person or a spacecraft.