Big asteroid to buzz Earth on Halloween, not another like it until 2027

An unexpected and large asteroid is coming around for a rare flyby, zipping past Earth close enough for scientists to get a good look.

Vesta gave us a good look at what an asteroid looks like. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

We know minute details about the surface of Pluto. A rover's getting personal with rocks on Mars. But we don't know everything about space. Sometimes we get some scientifically interesting surprises right up close to Earth. Asteroid 2015 TB145 is one of those.

The asteroid popped up October 10 during a survey by Pan-STARRS I (Panoramic Survey Telescope & Rapid Response System). The telescope's main job is to spot and track asteroids and comets "that might pose a danger to our planet." It is constantly discovering new near-Earth asteroids.

Asteroid 2015 TB145 is notable for both its size and how close it will come to Earth. "The flyby presents a truly outstanding scientific opportunity to study the physical properties of this object," a NASA bulletin notes.

We won't get another known asteroid this big at this close of an approach until 1999 AN10 arrives in August 2027.

Asteroid 2015 TB145 is coming in at 1.3 lunar distances, which is a measurement of the distance from the Earth to the moon and one that can vary with the moon's orbit. (The average distance from the center of the Earth to the center of the moon is around 384,500 kilometers, or 238,900 miles, according to NASA.) That means we won't need Bruce Willis to save us all from an asteroid Armageddon.

The asteroid will be plenty far away, but still close enough for researchers to get excited about imaging it. NASA notes that the fast-moving object "may be cometary in nature." If that's the case, it could be made up of rock, ice and dust, whereas asteroids consist mainly of rock and metals.

Asteroids have been on the Internet's mind lately with unfounded warnings about a doomsday asteroid arriving last month. We're all still here and we will still all be here after 2015 TB145 makes it flyby.