30-metre-wide asteroid to pass between Earth and the moon on Wednesday

On the afternoon of Wednesday, March 5th, a roughly 30-metre-wide asteroid will be passing by the Earth close enough to dip inside the orbit of the moon.

This asteroid, named 2014 DX110, was discovered just four days ago, on Feb. 28, 2013, and astronomers tracking it already have a good idea of its size and its orbit around the sun. Based on its brightness, they estimate that 2014 DX110 is about 20-30 metres wide, and around 16,000 metric tons. It's specifically an Apollo asteroid — so called because its orbit is both larger than Earth's orbit, and takes it on a path that crosses Earth's orbit. Since it comes so close to Earth on this pass, it's also considered to be a Potentially-Hazardous Asteroid (PHA), although that doesn't necessarily mean that it's going to hit us at some point. Being named a PHA only means that it comes within a certain distance of Earth and it's big enough that if it actually did hit us at some point, it would do some noticeable damage.

For this particular pass of 2014 DX110, it comes exceptionally close to Earth (at least by astronomical standards) — just 347,000 kilometres, or roughly 90 per cent of the distance between the Earth and the moon. However, because space is so big, even coming that close to us, the chance of 2014 DX110 actually hitting Earth is around 1 in 10 million. That's a 99.99999 per cent chance that it will miss!

This video, taken from NASA-JPL's Small Object Database Browser, shows 2014 DX110's roughly 39-month journey around the sun:

Whenever an asteroid gets this close to us, there's always a concern about it hitting something, like the moon in this case (since there's no space junk out that far to hit) Fortunately for the moon, though, it's not in the path of 2014 DX110 — the asteroid actually misses the moon with a wider margin than it does the Earth, coming within about 373,000 kilometres. It can't count itself that lucky all the time, though. Twice last year — on March 17 and Sept. 11 — astronomers here on Earth detected bright flashes on the moon's surface, indicating that it had been hit by something big.

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At 20-30 metres wide, if 2014 DX110 actually did hit Earth at some point, it would be comparable to the asteroid that exploded over Chelyabinsk, Russia, back in February of last year.

The two aren't related, though, since they have different orbits around the sun. The Chelyabinsk asteroid came at the Earth on a trajectory that essentially had it 'diving out of the sun,' which is why it was able to hit us with no warning. With the orbit of 2014 DX110, it only approaches Earth from outside our orbit, which is regularly watched by satellites like NASA's NEOWISE and by astronomers on the ground. There are efforts to put missions into space to protect us from asteroids coming at us from closer to the sun, though. The B612 Foundation's Sentinel mission would circle the sun just beyond the orbit of Venus, looking outward towards our orbit to spy such objects.

If you'd like to watch 2014 DX110 as it flies past us, there are actually a couple of ways to do so, and you won't even have to brave the cold (or the heat, if you're in the southern hemisphere). Both the Slooh Space Camera and the Virtual Telescope Project will be broadcasting their views of the asteroid tomorrow — starting at 4 a.m. ET from the Slooh site, and at 3:30 p.m. ET from the Virtual Telescope page.

(Image courtesy: NASA/JPL/S.Sutherland)

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