A three-mile-wide (4.8 km) asteroid is about to make one of its closest approaches ever and become the third-largest NASA-designated “potentially hazardous” object in history to approach the Earth. Not only that, it’s arriving right in the middle of the Christmas season. Will it become a Christmas star, a celestial Grinch that stole Christmas or a hazard that even Rudolph’s nose can’t protect Santa Claus from?
The history of 3200 Phaethon is interesting and potentially disconcerting. Although it’s been around (and around the Sun) for ages, it was only discovered in 1983 by astronomers Simon F. Green and John K. Davies and visually confirmed by Charles T. Kowal, who determined it to be asteroidal, at least in appearance. Further analysis showed how special this space rock is. 1983 TB (its original name) has an orbit that brings it closer to the Sun than any other named asteroid. That prompted astronomers to name it Phaethon in honor of the son of the Greek sun god Helios. That Phaethon borrowed his father’s sun chariot and drove it without the proper license or training, resulting in him getting too close to burning up Earth and resulting in Zeus tossing a thunderbolt that stopped the chariot and killed Phaethon.
Speaking of getting too close to the Earth, the real 3200 Phaethon does that too. Reverse calculations prior to its actual discovery show that it was only 5 million miles away when it passed on December 16, 1974. This year, it will be 6.4 million miles away, or 27 times the average distance between Earth and the moon. If you’re still around then, it will be 1.8 million miles away in 2093.
That may sound like a long way off, but it’s close enough for the International Astronomical Union's Minor Planet Center to deem it a potentially hazardous near Earth object, which means its impact could cause serious regional damage and it has the potential and proximity for impact. In fact, 3200 Phaethon is already affecting the Earth in another way. Astronomer Fred Whipple determined that the asteroid’s unusual orbit matches that of meteors that make up the annual mid-December Geminids meteor shower, making Phaethon their proud papa.
Yeah, yeah, yeah … that’s all very interesting but what about Christmas? Since 3200 Phaethon isn’t visible to the naked eye (although it can be seen this year with low-powered telescopes between December 11 and 21), it’s not the Christmas star. And it doesn’t appear that this is its year for a big impact – and a three-mile-wide asteroid would make a BIG impact. Some estimates suggest a mile-wide asteroid hitting New York City would destroy it and everything else from Washington DC to Boston, not to mention creating a dust cloud capable of blocking the Sun and ending most life on Earth.
Luckily, it doesn’t look like even the entire collection of naughtiness on Earth is enough to deliver that lump of coal in our stockings this year. We’re safe and so is Santa.