NGC 3242

NGC 3242, also known as the Ghost of Jupiter, is a planetary nebula located in the constellation Hydra. It was discovered by William Herschel on March 5, 1785. The nebula's name stems from its resemblance to the planet Jupiter when viewed through a small telescope.

The central star of NGC 3242 is a white dwarf, a hot, dense remnant of a star that has exhausted its nuclear fuel. The colorful layers of gas surrounding the white dwarf were expelled by the star during its red giant phase. These layers are ionized by the intense ultraviolet radiation emitted by the white dwarf, causing them to glow.

The nebula exhibits a complex structure with a bright inner shell surrounded by a fainter, more extended halo. The inner shell appears bluish-green, while the outer halo has a reddish hue. This color variation is due to the different elements present in the gas and their respective ionization states. Oxygen ions typically emit green light, while hydrogen and nitrogen emit red light.

NGC 3242 is estimated to be about 1,400 light-years away from Earth. Its apparent size is about 25 arcseconds, corresponding to a physical diameter of roughly 0.3 light-years. The central star has a surface temperature of approximately 75,000 Kelvin.

Amateur astronomers can observe NGC 3242 using telescopes with apertures of at least 6 inches. Larger telescopes reveal more detail in the nebula's structure and coloration. It is a popular target for astrophotographers due to its intricate details and vibrant colors. Spectroscopic studies of NGC 3242 have helped astronomers understand the processes involved in the formation and evolution of planetary nebulae and the eventual fate of Sun-like stars.