There are many images of our home planet taken from space, and they rarely fail to put things in perspective. Yet, have you ever seen our planet, from space, in motion?
The video above was taken by Nasa's Juno probe as it flew past us on 23 October. That grey mass to the left of the screen at the start, drifting right, is the Moon, orbiting the blue Earth. This is what it would look like to approach the Earth in a spaceship. It is incredibly cool. (And that music? That's a composition by Vangelis, the guy who did the soundtracks for Blade Runner and Chariots of Fire - Nasa has good taste.)
Juno, as its name may suggest, is on its way to explore Jupiter. It launched in August 2011, with enough momentum to reach as far as the asteroid belt before gravity pulled it back in towards the Sun - all part of Nasa's plan. As it reached the Earth again and skimmed past it received a gravity boost of a further 7.3km/s relative to the Sun, which should give it the velocity needed to reach Jupiter on the other side of the Solar System by July 2016. Once it's in orbit there, it will study the gas giant's clouds, and what's beneath them.
The video Nasa made of Juno's flypast opens with the probe roughly a million kilometres from Earth. The Moon's orbit is roughly 385,000km, which explains why the Moon shoots off to the right as Juno moves inside its orbit. Juno actually spins as it's flying along, twice per minute, so this video is a sped up one with two frames captured per minute of the same angle by Nasa engineers.
In other "things flying closely past the Earth" news, asteroid 2013 XY flew through our neighbourhood this morning:
It's probably between 30 and 70 metres across, which is considerably larger than the 15-20 metre Chelyabinsk meteor of February this year. And, best of all, we only spotted it five days ago. That's not a lot of warning for something potentially destructive (though, just to emphasise, there's no chance of this thing hitting us). Still, it goes to show just how big space is, and how little of it we know about, even in what we might consider our local community.