This shot is out of this world
It is an eclipse of the Sun, but not one as we know it.”It’s like being in the wrong solar system,” gasped one NASA scientist after she gazed at the images.
The unearthly view was snapped on February 25 by one of two satellites in the space agency’s STEREO (Solar TErrestrial RElations Observatory) project to unravel the mysteries of the Sun.
Launched in October, the twin craft are in an orbit around the Sun that almost exactly matches our world’s path. However one satellite, STEREO-B, is trailing about 1.6 million kilometres behind the Earth, while the other, STRERO-A, is travelling ahead.
Last month, during a test of STEREO-B’s cameras, the scientists commanded the craft to image the Moon as it passed in front of the Sun.
What they saw delighted them.
“What an extraordinary view … we caught a lunar transit of the Sun,” said the NASA scientist, Dr Lika Guhathakurta.
“The images have an alien quality. It’s not just the strange colours of the Sun. Look at the size of the Moon; it’s very odd.”
By pure coincidence the relatively tiny Moon, when seen from Earth, looks exactly the same size as the much bigger and far more distant Sun.
So, during a solar eclipse our only natural satellite can block out the solar disc, bringing darkness in the middle of the day.
But STEREOB is about 1.6 million kilometres from Earth, so to it the Moon looks 4.4 times smaller than it does to us.
The Sun looks different because the spacecraft took the pictures using four different extreme ultraviolet light wavelengths.
The scientists hope to combine images from the two satellites to make stereo movies of the Sun that will help them understand massive explosions, called coronal mass ejections, that can hurl a billion tonnes of gas into space, sometimes towards our planet.