A cluster of galaxies in the constellation Hydra.

The Chandra X-ray image of Hydra A, a galaxy cluster 840 million light years from Earth, shows strands of 35-40 million degree Celsius gas embedded in a large cloud of equally hot gas that is several million light years across. Also a bright white wedge of hot multimillion degree Celsius gas is seen pushing into the heart of the cluster. As the largest gravitationally bound objects in the universe, galaxy clusters provide crucial clues for understanding the origin and fate of the universe.