A large space rock resembling a skull narrowly missed Earth shortly after 1 p.m. ET Saturday. NASA says asteroid 2015 TB145 is a "dead" comet that once spewed debris across the solar system. In NASA terminology, that means it has "shed its volatiles" that would produce the visible tail seen on some comets.
It missed Earth by about 300,000 miles (slightly farther away than the moon). The rock, dubbed 2015 TB145, was visible to those with good telescopes.
Gianluca Masi, astrophysicist and curator of science at Planetario di Roma, featured a live stream through the Virtual Telescope Project
in order to track the asteroid as it cruised by Earth. "I always like looking at those close approachers," he told CNN. "They (show that) we do live in such dynamic solar system, where collisions play such a big role in shaping planets, Earth included.
"Now we are aware of those brushing visitors and are studying them, but in ancient times they had such strong effects on life and evolution on this planet," he said.
Calling it "one of the best radar targets of the year," a Jet Propulsion Laboratory report said
that "the flyby presents a truly outstanding scientific opportunity to study the physical properties of this object."
As viewed from Earth the asteroid was traveling through Orion on October 30-31.
It's a good thing it missed our planet, though. The asteroid is estimated to be 600 meters wide and traveling at 78,000 mph. By comparison, the meteorite that exploded in the sky over Chelyabinsk, Russia, in 2013 was about 20 meters wide.
Asteroid 2015 TB145 was the biggest known object to pass so close to the Earth until 2027.
Of course, the key phrase there is "known object." Until October 10, the space agency didn't know about 2015 TB145; more attention was on asteroid 2009 FD, which passed within about 4 million miles of Earth on October 29.
On October 10, asteroid 2000 FL 10, which had some people crying doom
, missed Earth by 15 million miles.
JPL runs NASA's Near Earth Object Office
to keep track of such celestial visitors. You can follow its news on Twitter at @asteroidwatch
This isn't the first time an asteroid has come close to our planet in late October. On October 30, 1937, the binary asteroid Hermes -- an alarmingly regular visitor
to these parts -- came within 500,000 miles of Earth. Hermes' two parts are each about 600 to 900 meters wide.
However, Hermes' orbits have been well-plotted in recent years. According to a JPL engineer quoted in a 2003 Cornell article
, "there is no cause for worry in our lifetimes."