An image of the asteroid Gaspra.
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It's Asteroid Time!
News story originally written on March 17, 1998

There seems to be a lot going on OUT THERE involving asteroids! Let's take a look!

For the last three years, NASA astronomers Robin Evans and Karl Stapelfeldt have hunted through nearly 28,000 Hubble images...their find -- about 100 small asteroids. These asteroids are essentially rocks (1-3 kilometers in size) that orbit between Mars and Jupiter in an area called the main asteroid belt.

"The archive images are distributed fairly evenly across the sky, so we find asteroids according to both their position in the sky and their number," Evans said. "As expected, we see the asteroids concentrated towards the ecliptic plane and we see small asteroids because they are the most numerous. Small main-belt asteroids such as these are the ones most likely to evolve into Earth-crossing asteroids due to encounters with their larger neighbors. Some of the asteroids in our survey could eventually migrate toward Earth."

It is this concern of asteroids coming too near the Earth that is the basis of our next news item! An asteroid discovered just last December (named 1997 XF11) is predicted to have a close encounter with the Earth in just 30 years. In October 2028, this mile-wide asteroid will pass within 600 thousand miles of the Earth. This is considered so close that it has been added to the 'potentially hazardous asteroids' list or PHA's. These PHA's come dangerously close to the Earth and so are monitored very closely. At this time, no PHA is in danger of impacting the Earth.

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