The Ghost of Jupiter, also knows as NGC 3242, Caldwell 59, or The Eye, is a planetary nebula. A planetary nebula is a growing shell of ionized gas that comes from and surrounds a large dying star. They absorb ultraviolet radiation from the star and reflect it back at us through fluorescence. The Ghost of Jupiter makes up a key part of the constellation Hydra, and observing.skyhound.com records it as being about 2800 light years away. The Ghost of Jupiter was discovered back in 1785 by William Herschel as H IV.27. It was then observed by John Herschel as h 3248 in the 1830s. John Herschel would go on to put it in the 1864 General Catalogue, which would later become the J. L. E. Dreyer's New General Catalogue of 1888.
The Ghost of Jupiter has a maximum angular size of 51.09 arc seconds, which corresponds to a linear size of 0.69 light years. Through a normal telescope the nebula looks greenish-blue, and if you have a strong enough telescope you can see the glowing outer halo. The inner part is the star, and that glows blue because it is very hot and is also opaque. The outer gas is oxygen and is green because it is not opaque, so it reflects different shades of ultraviolet light than the star itself. You can also see a ring around the nebula that makes it look almost like a mini version of Saturn.
|Right Ascension (J2000)||10:24:48.00|
|Filters used||B (Blue), C (Clear), R (Red), V (Green)|
|Exposure time per filter||B, V, and R (300s); C (60s x 5)|