Antennae interacting galaxies. Chandra X-ray tele- scope image of gas superbubbles (orange) in the interacting Antennae galaxies (NGC 4038 & 4039). As the galaxies collide, their gas and dust is compressed until nuclear reactions begin, leading to starbirth. After a few million years, the stars explode as supernovae to form vast numbers of expanding bubbles. The bubbles contain heavy elements and X-ray emitting gas at several million degrees Celsius. The bubbles merge to create these superbubbles, some of which have diameters of over 5000 light years. Some of the point X-ray sources (yellow) are black holes and neutron stars. Image taken by the ACIS instrument on 1 December 1999.