Space delivers Earth a hippo-shaped asteroid for Christmas

2003 SD220.
2003 SD220. Photo credit: NASA/JPL

An asteroid that looks remarkably like a hippo is zipping past the Earth today.

2003 SD220, as astronomers call it, won't be this close again for another 400 years.

"Do you want a hippopotamus for Christmas?" NASA's Jet Propulsion Laboratory wrote on Twitter. "You're in luck. Hippo-shaped #asteroid 2003 SD220 will fly safely past Earth."

NASA described it as looking "similar to that of the exposed portion of a hippopotamus wading in a river".

2003 SD220 is 1.6km across, and will be only 2.9 million kilometres away - close by astronomical standards.

It rotates only once every 12 days, which is slow for an asteroid, and it's wobbling.

"Known as 'non-principal axis' rotation, it is uncommon among near-Earth asteroids, most of which spin about their shortest axis," NASA said.

Images of the asteroid were taken by radar.

2003 SD220's last Earth fly-by was on Christmas Day (NZ time) in 2015, more than 10 million kilometres away.

According to Purdue University's impact calculator, if the hippo-shaped rock slammed into Earth at an angle of about 45 degrees it could create a crater about 22km across.

Newshub.