The University of Arizona

Just Coming Through: Asteroid Toutatis

By Daniel Stolte, University Communications | December 12, 2012
This picture shows what an artist thinks Toutatis might look like. Image courtesy Steve Ostro, NASA/JPL.
This picture shows what an artist thinks Toutatis might look like. Image courtesy Steve Ostro, NASA/JPL.

UA astrophotographer Adam Block caught asteroid Toutatis with the Schulman Telescope at the UA Mt. Lemmon SkyCenter as it zipped by the Earth on Dec. 11.

Adam Block recently received the Advanced Imaging Conference Hubble Award for his contributions to astrophotography. The Schulman Telescope is in the background. (Photo: Dave Harvey)
Adam Block recently received the Advanced Imaging Conference Hubble Award for his contributions to astrophotography. The Schulman Telescope is in the background. (Photo: Dave Harvey)
While Toutatis was flying by, astronomers at NASA's Goldstone Observatory scanned the space rock with radar to get a better idea of its irregular shape. (Image: NASA)
While Toutatis was flying by, astronomers at NASA's Goldstone Observatory scanned the space rock with radar to get a better idea of its irregular shape. (Image: NASA)

On the evening of Dec. 11, asteroid Toutatis whizzed by the Earth at a comfortable yet – cosmically speaking – close distance of about 18 times the distance to the moon. At three miles long, the peanut-shaped space rock is about half as big as the one believed to have slammed into the Caribbean 65 million years ago, sealing the fate of the dinosaurs.

Among the many telescopes following the extraterrestrial visitor as it tumbled by before disappearing out of view was the Schulman Telescope at the University of Arizona Mt. Lemmon SkyCenter. Operating the instrument remotely, UA astrophotographer and astronomy educator Adam Block took several hundred exposures of five seconds each during the asteroid’s 15-minute fly-by and assembled them into a video animation.

“Most asteroids are farther away and would move against the background stars more slowly, but since Toutatis is passing close to the Earth, its motion against the sky appears very fast,” Block explained.

Block said Toutatis is special in that it is a so-called Potentially Hazardous Asteroid. “It does come close to us, so this is one we want to keep an eye on,” he said. “These asteroids are monitored and their orbits are calculated to determine if they can impact us at any point in the future.”

He explained that the trajectories of asteroids are periodically updated to keep track of changes and make sure they don’t pose an impact hazard. “Each time they come close to the Earth-moon system, the gravitational interactions can cause small perturbations in their orbits,” Block said.

Even the tiny forces generated as an asteroid’s absorbs and reflects sunlight nudge it off course ever so slightly over time.

Through programs such as the Catalina Sky Survey, the UA is at the forefront of asteroid research and tracking. The UA also is the only university to ever lead a mission to visit an asteroid, scoop up a soil sample and bring it back to Earth. That mission is called OSIRIS-REx.

Block said although Toutatis would not have been visible with binoculars as some news sources claimed, a small telescope would have been sufficient.

“When they come close, we’re able to see the reflected light quite easily,” he said. “This one was actually quite bright."

"But of course, the ones that are really interesting to us are the ones we don’t know about, which is why programs such as our Catalina Sky Survey are so important.”