Newfound asteroid whizzes between the Earth and the Moon this week

Discovered just two days ago, a small asteroid will be whizzing past the Earth on Wednesday night, coming within two-thirds the distance to the Moon.

Asteroid 2013 RZ53 was found early Friday morning by astronomers working at the Steward Observatory, at the University of Arizona, as part of the Catalina Sky Survey. Astronomers from Australia and Illinois helped to track the asteroid, and found that it's about 3 metres wide, its orbit is very close to Earth's, and it even flies along with us as we make our way around the Sun. On Wednesday night, 2013 RZ53 will come within 0.6 lunar distances of Earth, or roughly 230,000 kilometres.

2013 RZ53 is an Apollo asteroid. These are a specific type of asteroids that cross Earth's orbit, putting them into a class of 'potentially-dangerous asteroids'. Astronomically speaking, it's coming pretty close to us, but it's well outside the orbit of our satellites, and there's no chance of it hitting the Earth. Still, based on the astronomers backtracking the orbit of this space rock, that's apparently the closest approach it's made since March of 1954.

This particular Apollo asteroid won't likely get back this close to us until March 2073. It'll probably just make another close fly by, but even if it managed to get close enough to actually hit us, it's doubtful that it would cause much more than a brief light show. For comparison, the asteroid that entered the atmosphere over Russia back in February is estimated at being over five times the size of 2013 RZ53, and that size is what helped it survive to get so close to the ground.

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What's particularly remarkable about the discovery of 2013 RZ53 is its small size. Astronomers (both professional and amateur) have discovered a lot of asteroids so far, but the smaller an asteroid is, the harder it is to spot. Sometimes we only see asteroids this small until after they've passed us by. The fact that they saw this one over five days before it swings so close to us shows just how dedicated these survey astronomers are, and just how skilled they're getting at spotting these asteroids.

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