V838 Monocerotis, red giant
V838 Monocerotis is one of the biggest mysteries in space. It was noticed in 2002 when it exploded with light and became one of the biggest stars we knew of for a while. Then, it retracted back into itself and became more of an average size. Initially astronomers thought it was a nova-type explosion, but now, they really aren’t sure. Whatever it is, it sure is purty!