Asteroids are small rocky objects that orbit the sun, just like planets do. But unlike planets, asteroids are much smaller. They are typically formed out of matter leftover from the formation of the solar system. Most asteroids are found in the asteroid belt, which is between the orbits of Mars and Jupiter.
A newly-discovered asteroid, Oumuamua is one-quarter mile wide and almost two miles long. Scientists think that this asteroid traveled through the Milky Way for millions of years before swinging through the solar system.
Oumuamua may provide new clues about how solar systems form. Giant telescopes show that this asteroid varies in brightness, and it spins on its axis every seven-and-a-half hours. Analysis suggests Oumuamua is very dense and made up of rock and possibly metals. It’s surface looks red because of radiation from cosmic rays. So far, no water or ice has been found on the asteroid.
Traveling at 85,700 miles per hour, Oumuamua was 124 million miles from earth when it was first discovered. Scientists predict that the asteroid will pass Jupiter’s orbit in May of 2018 and travel beyond Saturn’s orbit the following January.
Astronomers believe asteroids similar to Oumuamua pass through the inner solar system about once a year but are hard to spot. Only recently have telescopes been powerful enough to find them.
According to Lindley Johnson, NASA Planetary Defense Officer, “we are fortunate enough that our sky survey telescope was looking at the right place at the right time to capture this historic moment. This serendipitous discovery is bonus science enabled by NASA’S effort to find, track, and characterize near-Earth objects that could potentially pose a threat to our planet.”