M1: The Incredible Expanding CrabCataloged as M1, the Crab Nebula is the first on Charles Messier’s famous list of things which are not comets. In fact, the Crab Nebula is now known to be a supernova remnant, an expanding cloud of debris from the death explosion of a massive star. The violent birth of the Crab was witnessed by astronomers in the…Read More

Galaxy Wars: M81 versus M82In the upper left corner, surrounded by blue arms and dotted with red nebulas, is spiral galaxy M81. In the lower right corner, marked by a light central line and surrounded by red glowing gas, is irregular galaxy M82. This stunning vista shows these two mammoth galaxies locked in gravitational combat, as they have…Read More

The Doubly Warped World of Binary Black HolesIf one black hole looks strange, what about two? Light rays from accretion disks around a pair of orbiting supermassive black holes make their way through the warped space-time produced by extreme gravity in this detailed computer visualization. The simulated accretion disks have been given different…Read More

Planet Lines Across WaterWhat’s causing those lines? Objects in the sky sometimes appear reflected as lines across water — but why? If the water’s surface is smooth, then reflected objects would appear similarly — as spots. But if the water is choppy, then there are many places where light from the object can reflect off the water and still come…Read More

Astronomy Picture of the DayHow fast can a black hole spin? If any object made of regular matter spins too fast — it breaks apart. But a black hole might not be able to break apart — and its maximum spin rate is really unknown. Theorists usually model rapidly rotating black holes with the Kerr solution to Einstein’s General Theory of…Read More