ASL What Is an Asteroid?

Asteroids. Today, we're going to learn all about asteroids. We'll talk about what they're made of, what they look like, and more. But first, let's pretend it's nighttime, and the sky is super dark. When you look up at the sky, what do you see? We know that most of the twinkling lights we see are stars, and some are the brightest planets, like Mercury, Mars, Venus, Jupiter, or Saturn. But let's take our pretend telescopes out and examine things more closely. Here's what a star looks like. Here's what the planet Venus looks like. See that other light in the sky? It's not a star or a planet. So what is it? If you said asteroid, you're right! What is an asteroid? Asteroids are pieces of leftover material from when our solar system was formed. An asteroid is a type of space rock. Like planets, asteroids also orbit the sun, but they are much smaller than planets. There are millions of asteroids in our solar system. They can range in size from a tiny piece of dust to hundreds of miles in diameter. What is an asteroid made of? Asteroids are made mostly of rock, but some also include parts of clay, oxygen, and silicon. These also happen to be some of the most abundant elements in Earth's crust. Some asteroids have metal in them as well. Those metals are mostly nickel and iron, but other precious metals like gold, platinum, and magnesium have also been discovered in asteroids. The outer part of asteroids is mostly made of rocks, and the surface of most asteroids is thought to be covered in dust. What does an asteroid look like? Asteroids look like some of the rocks that you might find on Earth, but many asteroids also have craters or holes in their surface. Craters form when asteroids crash into other objects in space, and when they crash, they often break into smaller pieces. Let's talk about the asteroid belt. In an area between Mars and Jupiter lies something called the asteroid belt. What's the asteroid belt, you ask? That's where most of the asteroids in our solar system hang out while they orbit the sun. The asteroid belt contains around a million asteroids that are over a half a mile long, and there are millions more that are smaller than that. Pretty cool, huh? Ceres is the largest asteroid in the asteroid belt. It is also thought to be the biggest asteroid in our solar system. Because it is so big, scientists decided to call it a dwarf planet. A dwarf planet is a smaller planet that does not fit all the qualifications to be called a regular planet. Sorry, dwarf planets! Sometimes an asteroid leaves the asteroid belt and gets caught up in a planet's orbit. These are called Trojan asteroids. There are thousands of Trojan asteroids that share Jupiter's orbit around the sun. Are asteroids visible from Earth? Most asteroids cannot be seen from Earth without using a telescope. However, one asteroid named Vesta can occasionally be seen from Earth with the naked eye. Vesta is the second largest object in the asteroid belt. It is also the brightest asteroid in the sky. Vesta can be seen when it's in the right position and if the sky is very dark. One cool thing about Vesta is that it has a giant crater on it that is almost as big as the asteroid itself. Vesta is also the first asteroid to be visited by a spacecraft. Even though asteroids move extremely fast, they appear to be motionless to us. Even an asteroid moving over 75,000 miles per hour looks like it is moving very slowly from Earth. In fact, you might even mistake it for a star. Are there any asteroids near Earth? Apollo asteroids are a large group of asteroids near the Earth's orbit. Most of these asteroids burn up in our atmosphere, causing powerful blasts high up in the sky. Occasionally, one of them falls to Earth. These are called bolides or fireballs because they are so bright. Are there any other cool facts about asteroids? You bet! Did you know that over 150 asteroids have a small moon that floats near them? And some asteroids even have two moons! Did you also know that NASA's space shuttles have flown by, orbited, and even landed on some asteroids? How wild is that? Some scientists have even questioned whether people could live on an asteroid. How would you like to be one of those people? How can I see an asteroid from Earth? Get ready to mark your calendars because scientists predict that on April 13, 2029, an asteroid flying past Earth will be visible to the naked eye. So whether you want to be the first kid that lives on an asteroid, or you'd rather just stay on Earth and watch as one passes by, asteroids are a pretty incredible part of our solar system. Now that we've learned some cool asteroid facts, let's put our knowledge to the test. Fill in the blank. Most of our solar system's asteroids are located in the asteroid belt. Did you get that? Awesome! True or false? Asteroids are made mostly out of ice. False. Asteroids are made mostly of rock, but some can also include clay, oxygen, and silicon, or metals like nickel or iron. What tool do you need to be able to see most asteroids in the sky? A telescope. True or false? NASA's spacecrafts have landed on asteroids. True! Great job, celestial scientists! The next time you have a chance to study the night sky, think about what we've learned today about asteroids. And if you have one, get out your telescope and see if you can pick out an asteroid among all of the stars and planets. Hope you had fun learning with us. Visit us at learnbright.org for thousands of free resources and turnkey solutions for teachers and homeschoolers.