The Horsehead Nebula is a cloud of ionized-hydrogen in the constellation Orion. These clouds are lit from within by young, hot stars. The interstellar dust absorbs the light from part of the ionized cloud creating this beautiful contrast. Image Credit: NASA, NOAO, ESA and The Hubble Heritage Team (STScI/AURA)
the Hubble telescope allows us to see farther than we've ever seen before. And due to its high-tech cameras, we can distinguish between stars' atmospheres. Older stars cool down and become red giants, while younger stars burn blue.