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Four months after it blasted off into space, Nasa's solar spacecraft has spread its sails - and now you can spot it from Earth!

The Advanced Composite Solar Sail System (or ACS3 for short) is a special test spacecraft which will orbit around the Earth for a few weeks..

The ACS3 is made up of a small satellite (about the size of a microwave) and four solar sails - large sheets of a special material which use the power of the Sun to propel the spacecraft forwards.

Nasa wants to test out different types of renewable energy technology, like solar sails, to see if they can be used on future exploration missions.

The ACS3 launched back in April earlier this year, and Nasa confirmed that it had reached its position, around two times higher that the International Space Station, and unfurled it's seven-metre-long sails on 29 August.

The solar sails are like a combination of a sailboat and solar panels.

As a sailboat is powered by wind in a sail, solar sails use sunlight to power the sail forward, getting rid of the need for traditional rocket fuel.

The spacecraft is also fitted with a number of cameras to allow scientists here on Earth to see how the spacecraft is doing.

The ACS3 will be put through its paces by Nasa engineers over the next few weeks, testing out it's movement abilities and whether the materials are right.

This will help engineers to develop technology for future Nasa space missions.

Nasa also says it can be tracked using their free app, to allow people to catch a glimpse of it sailing through the stars.