You are here! A new NASA photo from the depths of space shows a fragile Earth as never seen before. Our planet and its companion Moon hang against a starry background in a dramatic shot from the Messenger probe between us and the Sun.
The unmanned spacecraft looked back as it heads on a journey that will eventually put it in orbit around Mercury, the closest world to the Sun. It was looking for a type of asteroid called vulcanoids that it is thought may lie between us and the Sun but be invisible from Earth because of the Sun’s glare.
During one of its sweeps, it picked out the Earth and Moon from a distance of 114 million miles (183 million km). No detail is visible on their bright surfaces which “burned out” as the search tried to pick out the fainter, smaller chunks of rock. If we could zoom in, they would appear full phase rather than crescents because of Messenger’s viewpoint.
No vulcanoids have yet been found but if they do exist, they will provide vital clues about the formation of the inner solar system, say experts.
Messenger’s principal investigator Sean Solomon, of the Carnegie Institution of Washington, said: “Our searches for vulcanoids may not turn up any objects. But a discovery of even one vulcanoid would change our thinking about the evolution of Mercury. The solar system still has many surprises in store for us, so it makes sense for us to be ready for the unexpected.”
Messenger, which was launched in 2004, has two more orbits of the Sun to make before it settles around rocky Mercury next year. So far it has made three flights past Mercury on its convoluted journey, photographing parts of the planet never seen before including a spectacular spider formation in 2008 plus a giant crater last year.
Its discoveries include evidence of volcanic activity and details of its magnetic field and tenuous atmosphere. The new image of Earth and Moon, released by NASA yesterday, was taken on May 6. See the full-size image here.
Observations from Earth of Mercury’s rotation suggest that it has a liquid core. The planet may have formed in a huge cosmic collision.
• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available. Check out our monthly sky guide too!