An asteroid called 3200 Phaethon is expected to come so close to Earth that it's been classified as "potentially hazardous" by the International Astronomical Union's Minor Planet Center.
According to NASA, the asteroid has a diameter of about 3 miles which makes it the third-largest "potentially hazardous" asteroid to ever pass by the planet.
NASA expects Phaethon to travel closest to Earth on Dec. 16, when it's projected to be more than 6.4 million miles away. That’s around 27 times the average distance between Earth and the moon, which is 238,855 miles.
This will be the closest Phaethon has been to Earth since Dec. 16, 1974, when it was just over 5 million miles away, according to NASA. But back in the 70s, people were not aware of the asteroid until after it passed.
It's not expected to be this close to our planet again until 2093 when it's projected to pass even closer at 1.8 million miles away.
Astronomers are curious about Phaethon because it's believed to be the “parent body for the Geminids meteor shower, which lights up the night skies in mid-December,” according to CBS News.
Meteor showers are most commonly associated with comets and not asteroids, making Phaethon "an unusual object," NASA said. Some researchers believe it could even be an inactive comet nucleus.
"The 2017 apparition is the closest to Earth since the asteroid's discovery, so it may be possible for optical observers to detect new activity," NASA said, adding that they are planning radar observations to hopefully obtain detailed images of Phaethon. At its closest, the asteroid may be visible with a small telescope in dark skies.
3200 Phaethon was named after a figure in Greek mythology, Phaethon, son of the Sun god, Helios. In the legend, Phaethon lost control of his father's chariot and almost set the Earth on fire.