From NASA
Imagine you’re a Brontosaurus with your face in a prehistoric tree top, munching on fresh leaves. Your relatives have ruled planet Earth for more than 150 million years. Huge and strong, you feel invincible.
You’re not.
Fast forward about 65 million years. A creature much smaller and weaker dominates the Earth now, with brains instead of brawn. Its brain is a lot larger than yours relative to its body size – plenty big enough to conceive a way to scan the cosmos for objects like the colossal asteroid that wrought the end of your kind.
The creature designed and built WISE, NASA’s Wide-field Infrared Survey Explorer, to search for “dark” objects in space like brown dwarf stars, vast dust clouds, and your nemesis – asteroids. WISE finds them by sensing their heat in the form of infrared light most other telescopes can’t pick up.
“Our instrument is finding hundreds of asteroids every day that were never detected before,” says Ned Wright, principal investigator for WISE and a physicist at the University of California in Los Angeles. “WISE is very good at this kind of work.”
Visible-light telescopes conducting past asteroid surveys may have missed a large population of darker asteroids that WISE is now flushing out of hiding. Most of the asteroids WISE is finding are in the main asteroid belt between Mars and Jupiter, but a fraction of them are different-they’re the kind of Earth-approaching asteroids that send shivers all the way down a Brontosaurus’ spine.
“WISE has only been in orbit for about three months, but we’ve already found a handful of asteroids classified as ‘potentially hazardous,’ including one seen in 1996 but lost until re-observed by WISE. To be named ‘potentially hazardous,’ an asteroid has to pass within about 5 million miles of Earth’s orbit. One of our discoveries will cross Earth’s orbit less than 700,000 miles away.”