Two giant radio telescopes teamed up to image a peanut-shaped asteroid that zoomed by Earth late last month.

The resulting radar images, which researchers combined into an asteroid flyby video, show that the asteroid, known as 1999 JD6, is a "contact binary" consisting of two lobes joined together.

NASA scientists collected this collage of radar images of near-Earth asteroid 1999 JD6 on July 25, 2015.
NASA scientists collected this collage of radar images of near-Earth asteroid 1999 JD6 on July 25, 2015.
Credit: NASA/JPL-Caltech/GSSR

"Radar imaging has shown that about 15 percent of near-Earth asteroids larger than 600 feet [about 180 meters], including 1999 JD6, have this sort of lobed, peanut shape," Lance Benner, of NASA's Jet Propulsion Laboratory in Pasadena, California, who leads NASA's asteroid radar research program, said in a statement.

The asteroid 1999 JD6 flew within 4.5 million miles (7.2 million kilometers) of Earth — about 19 times the distance between our planet and the moon — in the early-morning hours of July 25. 1999 JD6 won't come that close to Earth again until 2054, NASA officials said.

That same day, scientists used NASA's 230-foot-wide (70 m) Deep Space Network antenna at the Goldstone Complex in California to bounce radar signals off the asteroid. Reflections from those signals were then received by the 330-foot (100 m) National Science Foundation Green Bank Telescope in West Virginia, NASA officials said.

This two-telescope strategy allowed the research team to observe features as small as 25 feet (7.5 m) wide on the asteroid.  

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Asteroids are fascinating for lots of reasons. They contain a variety of valuable resources and slam into our planet on a regular basis, occasionally snuffing out most of Earth's lifeforms. How much do you know about space rocks?
Earth Causes Asteroid-Quakes
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The new observations revealed that 1999 JD6 is about 1.2 miles (2 km) long, and extremely elongated, researchers said.

"I'm interested in this particular asteroid because estimates of its size from previous observations, at infrared wavelengths, have not agreed," Sean Marshall, a graduate student at Cornell University who's studying 1999 JD6,  said in the same statement. "The radar data will allow us to conclusively resolve the mystery of its size to better understand this interesting little world."

Previous research had already shown that 1999 JD6 rotates once every 7.5 hours. The video compiled from the new radar images spans 7 hours and 40 minutes.

Follow Kasandra Brabaw on Twitter at @KassieBrabaw. Follow us @Spacedotcom, Facebook and Google+. Originally published on Space.com.