Big Dipper's Alcor A and B (image) American Museum of Natural History Share Print E-Mail Caption Alcor, a star in the middle of the Big Dipper's handle, has a newly found red dwarf companion (circled in green). Project 1640 astronomers discovered the faint star by blocking out almost all of Alcor's light with a coronagraph. The halo of speckles around the coronagraph's occulting mask is caused by the wave-like properties of light from Alcor's residual glare. The actual diameters of both stars take up just a tiny fraction of a pixel. Credit Project 1640/AMNH and Digital Universe Atlas Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.