ASTEROID 2005 YU55 will have buzzed Earth by the time you read this, but the quest to understand it will have only just kicked off.
The 400-metre-wide rock is our first chance to study an asteroid of this size close up, a distance of 324,600 kilometres to be precise. In 1976, a similar-sized rock came this close but we didn't spot it.
As New Scientist went to press, radio waves from the Goldstone Deep Space Communications Complex in California had confirmed that 2005 U55 is a carbon-rich, C-type asteroid, the sort credited with bringing water to Earth. A closer look, as it hurtles past at 13.7 kilometres per second, could help unravel this process.
Measurements should also further reveal its shape, which seems elongated. "A full shape will come after some days of watching it spin ...