Stingray nebula. Hubble telescope light image of the Stingray nebula, the youngest known planetary nebula yet discovered in 1998. A nebula is a cloud of gas and dust. The bright central star is in the middle of a green ring of gas, with a companion star at upper left. Bubbles of gas are at lower left and upper right; red curved lines represent bright gas heated by a shock" when the central star's wind hits the walls of the bubble. Colours are emitted by nitrogen (red), oxygen (green), and hydrogen (blue). The nebula is 130 solar systems large, located 18,000 light years away in the Ara (Altar) constellation. Data obtained March 1996."