“We can expect a totally different kind of trick-or-treater this coming Halloween. A rather large asteroid—discovered less than three weeks ago—is set to to fly past the Earth at a distance not seen in nearly a decade. The asteroid, dubbed 2015 TB145, was discovered on October 10 by astronomers using the Pan-STARRS telescope. The object measures about 280 to 620 meters (920 to 2,034 feet) in diameter, so it’s pretty big—about the size of a skyscraper. Or two. Not only that, it’s moving at a velocity of 35 km/s (78,830 mph or 12,600 km/h), which NASA describes as “unusually high.””