X Ray Mystery in RCW 38 . ... CXC , NASA Explanation: A mere 6,000 light-years distant and sailing through the constellation Vela , star cluster RCW 38 is full of powerful stars. It's no surprise that these stars, only a million years young with hot outer atmospheres, appear as point-like x-ray sources dotting this x-ray image from the orbiting Chandra Observatory . ... The image is color coded by x-ray energy, with high energies in blue, medium in green, and low energy x-rays in red. ...