An asteroid as large as a house flies by 350,000km . from Earth

Astronomers photographed asteroids as large as a house with a diameter of about 4.2 - 9.5m graze the Earth.

Asteroid 2022 AC4 looks like a small bright spot (marked with an arrow) in this image taken from Italy on January 10.

 On January 11, the asteroid 2022 AC4 flew past only 93,300km from Earth. This number may sound huge to humans, but in reality this distance is less than a quarter of the distance between the Earth and the Moon. According to NASA data, 2022 AC4 is the closest asteroid to Earth in at least two months.

At the closest point to Earth, 2022 AC4 moves at 30,000km/h. Experts estimate the diameter of this asteroid to be about 4.2 - 9.5m, meaning it could be as big as a house.

Astronomer Gianluca Masi, Virtual Telescope Project Manager in Italy, photographed 2022 AC4 as it passed by on January 10. At the time of capture, the asteroid was about 350,000 km from Earth. In the image, 2022 AC4 is a faint blip among a series of light trails created by blurred stars. It is marked by a small arrow in the middle of the photo.

The Mount Lemmon Survey program detected 2022 AC4 on January 9, just days before it flew by Earth. Despite its close proximity, 2022 AC4 was not classified by NASA's Center for Near-Earth Object Studies (CNEOS) as a Potentially Hazardous Asteroid (PHA) because it does not pose a threat to Earth.

To be classified as a PHA, an asteroid not only needs to come close to Earth, but also needs to reach a certain size. Specifically, an asteroid that is more than 7.4 million kilometers away from Earth or has a diameter of less than 152 meters is not considered a PHA, according to CNEOS.

2022 AC4 isn't the only asteroid that's caught the eye this time around. On January 19, asteroid 7482 (1994 PC1) about 1,000m wide will pass 1.93 million km from Earth. It is not expected to crash into Earth but still has a PHA rating. It won't come this close again until the next century.