The Lemon Slice Nebula is a challenging object and the northernmost planetary nebula in the sky. Credit: NASA/ESA/Hubble
Of the approximately 3,000 planetary nebulae known in the galaxy, most are asymmetrical. But one planetary in Camelopardalis, just 7.5° from Polaris, is the poster child for symmetry.
The Lemon Slice Nebula (IC 3568) is a young planetary spanning only some 0.4 light-year. Its central star is dying and glows feebly at magnitude 12.3. The nebula overall is a 12th-magnitude object and it lies approximately 4,500 light-years away.
It is notable for being one of the simplest nebulae known — almost perfectly spherical. The nebula contains an inner, brighter region of higher-velocity gas, spanning some 0.2 light-year.
NGC 3568 was discovered in 1900 by Robert Grant Aitken at Lick Observatory, using the 12-inch refractor.
