Asteroids are small, rocky objects that orbit the Sun. They are leftovers from the formation of our solar system about 4.6 billion years ago. Most of them orbit in the asteroid belt between Mars and Jupiter, though some have been knocked out of their original orbits by the gravity of nearby planets. Scientists estimate there are millions of asteroids in the solar system, ranging in size from hundreds of kilometers across to barely visible specks. NASA has been studying asteroids since the late 1950s, when the first spacecraft, Pioneer 3, flew past two asteroids. Since then, NASA has sent several spacecraft that have orbited, landed on, and flown by asteroids to learn more about their composition, structure and origins. NASA’s studies of asteroids have helped us understand how the solar system formed, and how we might be able to use these objects as a source of resources in the future. Here you can find the latest news, articles and videos about asteroids and NASA’s exploration of these fascinating objects.