ClassX Video Lessons Comets, Asteroids, and Meteors | Learn all about what they are made of and how they differ
When you think about space, what comes to mind? The moon, stars, and planets? Maybe the sun, satellites, and space stations? Today, we’re going to learn about three fascinating types of space rocks: asteroids, comets, and meteors. These rocks are like ancient leftovers from when our solar system was formed. Some are huge, while others are tiny. Let’s dive in and discover what makes each of these space rocks special!
Asteroids are the largest of the space rocks. They orbit the Sun in a region between Mars and Jupiter called the asteroid belt. This belt has two parts: the inner part, filled with metal-rich asteroids, and the outer part, mostly made of rocky asteroids. There are millions of asteroids, but only about 3,000 have names. The biggest one is Ceres, which is so large that scientists call it a dwarf planet. Ceres is about 295 miles wide and is the closest dwarf planet to the Sun.
Asteroids often have craters, which are holes formed when they crash into other objects in space. Some asteroids leave the asteroid belt and travel elsewhere, like the Trojan asteroids that move with Jupiter. Near Earth, there are over 10,000 asteroids called Apollo asteroids. Most of these burn up in our atmosphere, creating bright flashes called bolides or “fireballs.” Some, like superbolides, are incredibly bright and can be seen from places like Russia and California.
Comets are another type of space rock. They shine brightly in the sky and have icy cores made of frozen water, gases, rock, and metal, covered in black dust. This is why they’re nicknamed “dirty snowballs.” When a comet gets close to the Sun, its ice turns into gas, creating a glowing cloud called a coma. Comets also have long, bright tails that can stretch millions of miles!
Comets come from two places: the Kuiper Belt, beyond Neptune, and the Oort Cloud, far beyond our solar system. There are two types of comets: short-period and long-period. Short-period comets, like Halley’s Comet and Encke’s Comet, take less than 200 years to orbit the Sun. Halley’s Comet appears every 76 years, while Encke’s Comet orbits every 3.3 years. Long-period comets take over 200 years to orbit the Sun and come from the Oort Cloud.
Meteors are often called shooting stars, but they’re not stars at all! They start as meteoroids, which are small pieces of rock or metal that break off comets or asteroids. When these pieces enter Earth’s atmosphere, they become meteors. As they fall, they heat up and glow, creating a streak of light in the sky. Sometimes, many meteors burn up at once, creating a meteor shower, which looks like a sky full of shooting stars!
Meteors usually burn up quickly, but if a meteoroid survives the trip through Earth’s atmosphere and lands on the ground, it’s called a meteorite. Millions of meteors enter our atmosphere every day, but only about 500 meteorites reach the Earth’s surface each year. Scientists have collected over 10,000 meteorites for study, often finding them in deserts or cold places like Antarctica.
Next time you gaze at the night sky, keep an eye out for these amazing space rocks. Whether it’s a bright comet, a massive asteroid, or a dazzling meteor, our solar system is full of wonders waiting to be explored!
**Asteroids, Comets, and Meteors**
How many things can you think of that are found in space? The moon, stars, and planets? What about the sun, satellites, and space stations? In this video, we are going to be talking about three different types of space rocks: asteroids, comets, and meteors. These three types of rocks are believed to be leftover material from when the sun and the planets were created. Some of these rocks are hundreds of miles long, while others are only a few feet in size. Sometimes, people are confused about the differences between these rocks. Let’s find out what makes each of them different and what they do in our solar system.
**Asteroids** are the largest of the three kinds of space rocks. These chunks of rock circle the Sun in an area between Mars and Jupiter called the asteroid belt. The asteroid belt has an inner and an outer part. The inner part is made up of asteroids that contain metals like gold, iron, platinum, and nickel. The outer part contains asteroids mostly made up of rocks. There are millions of asteroids in our solar system, but only about 3,000 of them have been named. Ceres is thought to be the biggest asteroid in our solar system, measuring about 295 miles in diameter. Because it is so large, scientists decided to classify it as a dwarf planet. A dwarf planet is essentially a smaller version of the eight planets in our solar system. Ceres is one of five recognized dwarf planets. Another is Pluto, which was once classified as a planet but was downgraded to a dwarf planet in recent years. Ceres is the largest object in the asteroid belt and the closest dwarf planet to the Sun. In 2015, a spacecraft named “Dawn” orbited Ceres, meaning it flew all the way around it. In 2011, Dawn also orbited the second-largest object in the asteroid belt, called Vesta, which is the brightest asteroid in the sky and can sometimes be seen from Earth without a telescope.
Most asteroids contain craters or holes in their surface, which form when asteroids crash into other objects in space. Some asteroids have left the asteroid belt and entered other orbits, known as Trojan asteroids. Many of these move with the planet Jupiter as it orbits the Sun. Apollo asteroids are a group of asteroids near Earth’s orbit, consisting of over 10,000 asteroids, making it the largest group of objects near Earth. Most of these asteroids burn up in our atmosphere, causing powerful blasts high in the sky. Occasionally, one falls to Earth, referred to as a bolide or “fireball” due to its brightness. Parts of Russia and California have both experienced impacts from superbolides, which were 100 times brighter than a full moon when they fell—an incredible sight to witness!
**Comets** are another kind of space rock. They are also bright and appear as shining lights in the sky. A comet in the outer part of the solar system would be too small to be seen from Earth, even with a telescope. Comets have an icy core made up of frozen water and gases, mixed with bits of rock and metal, and covered by a layer of black dust. This is why they are nicknamed “dirty snowballs.” When a comet gets close to the Sun, the ice melts and transforms into gas, causing dust particles to spread out around the center or nucleus of the comet. These dust particles create a cloud called a coma at the head of the comet, which glows due to sunlight. A comet’s tail can be millions of miles long! Some comets can be seen without a telescope as they pass near Earth and the Sun.
Comets originate from either of two regions in the solar system: the Kuiper Belt, located just beyond the orbit of Neptune, or the Oort Cloud, situated beyond the outer boundary of the solar system. There are two types of comets: short-period and long-period. Short-period comets take less than 200 years to travel around the Sun. Two examples of short-period comets are Halley’s Comet and Encke’s Comet. Halley’s Comet orbits the Sun every 76 years, last seen in 1986 and expected to be visible again around 2061. Encke’s Comet has the shortest orbit of any known comet, completing its orbit every 3.3 years. Both Halley’s Comet and Encke’s Comet originated from the Kuiper Belt. Long-period comets have orbits lasting more than 200 years, with some taking over 1,000 years, and they originate from the Oort Cloud.
Now, let’s discuss **meteors**. These rocks are sometimes referred to as falling or shooting stars. They appear as thin streaks of light in the night sky, but they are not actually stars. Meteors begin as meteoroids, which are small pieces of rock or metal that break off a comet or an asteroid when they collide. They can also form from debris left behind by a comet. When these small pieces of rock are pulled into Earth’s atmosphere, they are called meteors. The meteor heats up and burns, making it red-hot. If multiple meteors burn up simultaneously, you can witness a meteor shower, which looks like thousands of shooting stars falling from the sky. Meteor showers can be predicted throughout the year, and if you get the chance to see one, don’t miss it—they’re truly spectacular!
Meteors only last for a few seconds before they burn up. A meteorite is a meteoroid that does not burn up in Earth’s atmosphere and instead falls to the Earth’s surface. Millions of meteors enter the Earth’s atmosphere every day; however, very few reach the surface as meteorites—about 500 a year, with most landing in the ocean. Some have been found in deserts or cold places like Antarctica, where the climate helps preserve them. Over the years, scientists have collected more than 10,000 meteorites for study.
The next time you look up at the night sky, you just might see a meteor, comet, or asteroid—three incredible types of rocks in our solar system!
