Students learn some basic facts about asteroids in our solar system, mainly about the size of asteroids and how that relates to the potential danger of an asteroid colliding with the Earth. Students are briefly introduced to the destruction that would ensue should a large asteroid hit, as it did 65 million years ago.

Engineers at NASA create technological tools to learn about asteroids. The Near-Earth-Object (NEO) project is aimed at studying how asteroids move so we can predict whether they will hit the Earth. Software engineers design the computer programs to make these predictions. Mechanical and aerospace engineers on this project have created space probes to learn more about asteroids by taking photographs of them and, in the case of the NEAR Shoemaker probe, even landing on a large asteroid. asteroid crater meteor space solar system After this lesson, students should be able to: Explain what asteroids are and compare them to other objects in the solar system. State how big an asteroid must be to cause mass destruction on Earth. Understand why engineers design technological tools to predict the movement of asteroids. In the 1998 hit movie "Armageddon," an asteroid the size of Texas is on a collision path with Earth and is predicted to destroy all life as we know it. How real is this scenario? Well, we will answer that question today, but first, let's look at some background information about asteroids. Asteroids are objects that revolve around the Sun, mostly in the region between Mars and Jupiter known as the asteroid belt (see Transparency #1), also shown in Figure 2. How big are asteroids? Actually, their sizes can be quite variable! The smallest known asteroid is 6 m (or, almost 20 ft.) across — it could easily fit in our classroom. The Gaspra Asteroid (show Transparency #2) is 17 km (or, more than 10.5 miles!) across. How big is that? Could we fit a city block, small town, a big city, our state, or the whole country across something that big? (Have students raise their hands for a quick vote. Answer: A small town.) More than 200 asteroids in the belt between Mars and Jupiter are more than 100 km across. If we were to drive 100 km from our school, where would we end up? (100 km is equal to about 62 miles. Be prepared to have some answers for students, depending on where you live. This helps students understand the scale.) What would happen if one of these asteroids hit the Earth? Well, it depends on how its size. Those that are less than 40 m across (about as big as a small office building), would be destroyed by the Earth's atmosphere and not do any damage. If one as large as 2 km in diameter hit the planet, it might cause disaster on a global scale. Not only would its crashing pieces cause instant destruction and death, but the dust created by the crash would set off a change in weather that would kill a huge fraction of all the living things on Earth. It is believed that this is what happened 65 million years ago when a meteor 6 miles across hit the Chicxulub Basin in Mexico, resulting in mass extinction, including dinosaurs. Fortunately, scientists predict that your chances of being killed by an asteroid impact are very low (1 in 40,000). Currently, no known asteroids are on a collision path with Earth. However, every 1 or 2 million years, the Earth could be hit by an asteroid large enough to cause global destruction and kill most people on Earth. To prevent this, engineers are seeking ways to destroy or divert asteroids before they hit us (just like in the movie "Armageddon")! Asteroids are objects ranging in size from 6 m to 933 km across that revolve around the Sun. The asteroid belt contains millions of asteroids that are less than 1 km in diameter. More than 750,000 are bigger, and of those, at least 200 are more than 100 km across. Asteroids in the outer part of the belt are composed mainly of carbon, while those located in the inner part of the belt are made primarily of minerals, since they are derived from melted objects. Although scientists are not certain how they came about, it is believed that they are the result of collisions of much larger objects occurring around the time that our solar system was formed. Some asteroids, on the other hand, are derived from the tails of comets. Scientists at NASA have been actively tracking near Earth asteroids (NEAs) to determine whether or not they will hit. Jupiter's gravitational field pulls on asteroids just enough to slowly change their trajectories. With the advancement of computer models and tracking devices (created completely, or in part, by engineers!), scientists can predict the future trajectories of asteroids. So far, they have found that no asteroids are on a collision course with Earth. Historically, the Earth was not always so lucky. A very long time ago — 65 million years to be exact — an asteroid hit an area in present-day Mexico, leaving behind a 300 km-wide crater. It is hypothesized that this asteroid causes the mass extinction of life around that time, including dinosaurs. More recently, in 1908, a smaller object (either an asteroid or comet tail) hit Siberia, destroying forested land in an area about 50 m in diameter. Fortunately, most asteroids that come within proximity of Earth do no damage. As small (<40 m in diameter) asteroids hit the atmosphere, they burn up, giving off the characteristic trademark of a meteor. (Meteors are small objects that have entered the Earth's atmosphere, either from comets, asteroids, or other objects in our solar system.) This also explains why the Moon looks more "beat-up" than the Earth. The Moon does not have an atmosphere, and therefore, even small objects may cause craters on the Moon upon collision. A celestial body that orbits the Sun; ranges in size from 6 m to 933 km. A celestial body with a solid core and followed by a tail of debris; normally has a highly elliptical orbit. A flash of light caused by particles from outer space entering the Earth's atmosphere; typically originate from asteroid collisions. Earth Impact Scientists and engineers are very interested in near-Earth asteroids because we know that at some point in the future (even if it is a million years away), the Earth could be impacted by an asteroid collision. It is important that scientists and engineers know what to look for in order to predict and prevent asteroid impacts that could cause devastation on Earth. While many people study the solar system for its beauty and tranquility, others study it to learn about the unknown to understand and help predict our celestial movement - both good and potentially dangerous movement. Voting: Ask true/false questions and have the students vote by holding thumbs up for true and thumbs down for false. Tally the votes and write the totals on the board. Give students the right answers: T or F: The solar system consists only of the Sun, the planets, and their moons. (Answer: False; there are millions of asteroids in our solar system.) T or F: If an asteroid hit the Earth, it would knock everyone off the planet. (Answer: False; asteroids are much smaller than the Earth. Most asteroids burn up when they hit the atmosphere and do no damage at all. Some large asteroids have done tremendous damage, but they are still not massive enough to knock things off the planet, or to knock the Earth out of orbit.) Idea Web: Ask students to brainstorm a list of possible consequences of an asteroid hitting the Earth. How does one of these consequences lead to another? (For instance, as the asteroid hits, it creates a crater and sends dust and debris flying, the dust obscures the Sun, less Sun causes lower temperatures, etc.). Help students see how the single event of an asteroid impact could set off a domino-like chain reaction of changes that impact life on the planet. Question/Answer: Have students answer the following question in a short paragraph in their journals or on a sheets of paper: What role do engineers have in preventing the catastrophe of an asteroid hitting the Earth? Build a scale model of objects in the solar system, with help from a NASA website at: http://science.nasa.gov/ssl/pad/solar/tutorials/lessons/solmod1.htm. Include in it an indication of where the asteroid belt would be. Grayzeck, Ed, Dr. National Space Science Data Center, National Aeronautics and Space Administration, Image Resources, "Planetary," May 17, 2007, accessed November 27, 2007. http://nssdc.gsfc.nasa.gov/image/planetary/asteroid/gaspra.jpg Lindstrom, Marilyn. Solar System Exploration, National Aeronautics and Space Administration, Multimedia, November 24, 2008, accessed November 27, 2008. http://solarsystem.nasa.gov/multimedia/gallery/Asteroid_Belt.jpg Transparency #1: Asteroid Belt (doc) Transparency #2: Gespra Astroid (doc) Transparency #1: Asteroid Belt (pdf) Transparency #2: Gespra Astroid (pdf)