In the week between March 4 and 10, four asteroids had passed close to Earth almost unnoticed. The largest was approximately 40 meters across, according to recent radar observations performed using NASA’s Goldstone radar antenna in California.
“The scary part about this one, of course, is that it’s something we didn’t even know about,” said Patrick Paolucci, president of the online Slooh Space Camera, a robotic telescope service that can be viewed live through a web browser.
The asteroid, dubbed 2013 ET, was discovered by the Catalina Sky Survey at the University of Arizona on March 3. It was noticed at this late stage because objects of that size can’t be detected until they get close enough. It made its close approach to Earth on March 9, passing by at just 965,606 kilometers, approximately 2.5 times the distance between the Earth and the Moon. A 7-meter wide asteroid called 2013 EC20 came even closer to Earth, passing at about 150,000 km, also on March 9.
The 2 other space rocks passing close to our planet were asteroid 2013 EC and asteroid 2013 EN20, making their planetary fly-bys on March 4 and March 10, respectively. The 12-meter asteroid 2013 EC passed by at roughly 383,000 kilometers, whereas the 23-meter asteroid 2013 EN20 passed just beyond Moon’s orbit.
Recent events have shown that the solar system is a very busy place and that our planet is regularly approached by mostly unseen space rocks. Amateur astronomers can assist with planetary defense however. Online databases and collaborative tools can enable vigilant hobbyists to discover near-Earth objects, refine their orbits with follow-up observations, and share information with the relevant authorities. The Slooh robotic telescope in Tenerife is a good example of this, as it was used to send images of asteroid 2013 ET to the Minor Planet Center, located at the Smithsonian Astrophysics Observatory.
Below, images of Asteroid 2013 EC by Gianluca Masi of The Virtual Telescope Project.