Canon has built what it claims is the world's largest CMOS sensor. It's 40 times larger than the biggest commercial dSLR camera sensors and is capable of shooting stars.
The imaging sensor is the part of the camera that captures the light coming in through the front of the lens -- essentially it replaces the film used in traditional cameras. It's covered with little light-snaffling photodiodes, or pixels. A million pixels is a megapixel, so an 8-megapixel camera has 8-million pixels.
Compact cameras mean small sensors, which mean small pixels, which means photos can become speckled with gritty noise in lower light. dSLRs pack larger sensors, usually up to 36x24 mm, known as full frame because they're the size of a 35mm frame of film.
By contrast, Canon's new CMOS measures 202x205mm, 40 times larger than full frame. Just look at the picture: the puny little chip on the right is a full-frame sensor, dwarfed by the behemoth on the left. If you were to stick it in a camera, it could only be operated by Peter Crouch. It won't appear in the cameras you or I buy, but Canon reckons it could be used for filming heavenly bodies -- the Patrick Moore kind, not Abbey Clancy -- as it's capable of capturing 60fps video even by moonlight.
More realistically -- although still pretty bonkers -- Canon has also developed an APS-H, 29x20mm CMOS chip that delivers 120 megapixels. That's some 7 times higher than Canon's top-of-the-line EOS-1Ds Mark III and EOS 5D Mark II dSLRs. The sensor records 1080p high definition video and can snap up to 9.5fps. There's no word on whether this will appear in proper cameras one day, but we're keeping our fingers crossed.