Visitors from outer space

Near misses by comets and asteroids are rare events, but in 2013, predictions were made that earthlings would experience at least three. A menacing, 1,000-foot-wide asteroid named Apophis which passed within 9 million miles of our planet—close by astronomical standards. Dubbed “the doomsday asteroid,” Apophis has an elliptical orbit around the sun that will bring it much closer to Earth again in 2036. Since its orbit was not precisely calculated, there were fears that it might strike us on that next visit—a catastrophic impact that would be equivalent to 25,000 atomic bombs.

But after closely analyzing Apophis’ trajectory during it’s last orbit, NASA says it has now “completely excluded any chance of impact in 2036” Several months later, a smaller asteroid, about 150 feet in diameter, missed Earth by a mere 21,600 miles—only about one tenth the distance from Earth to the moon. November 2013 brought the most spectacular visitor of all — what astronomers are called the comet of the century.

One of the newly discovered visitors from outer space, named ISON, broke up as it passed around the sun, its tail-formed by gases and dust boiling off its icy surface—was as bright in the night sky as a full moon. Comet watcher John Bortle told NBCNews.com that ISON may have a tail of “amazing length and surface brightness,” unmatched by any since the Great Comet of 1680. Asteroids and comets are cosmic debris left over from the birth of our solar system, about 4.5 billion years ago.