The "Ghost of Jupiter", NGC 3242, Hydra

Also known as the "Eye Nebula", it is one of the brighter planetary nebulae in the sky and even in a small telescope its characteristic colour of OIII emission - a blue-green, teal - is readily discerned. A star in the last stages of its evolutionary life, it has wafted off its outer layers leaving the exceedingly hot core as an 11th magnitude O-type white dwarf which causes the departing material to fluoresce. Planetary nebula phases are incredibly short-lived (in cosmic terms), the inner "eye" is material wafted off during the past 1500 years or so.  Distance from us is in the region of 4800 ly.