NGC 246 A ND NGC 6543: A DA M BLOCK / M OUN T LEM M ON SK YCEN TER / UNIV ERSIT Y OF A RIZON A S COLORFUL RING The Ring Nebula (M57) is one of the best-known planetaries in the northern sky and looks good in most any well-tracked image. But as with many planetaries, lots of cumulative exposure brings out its faint outer shell. To its northwest is spiral galaxy IC 1296. S CRYSTAL BALL With a diameter of 2.5 light-years, Abell 39 is the largest near-perfect spherical object known. Distant galaxies are visible through the nebula when imaged with larger instruments. S GHOSTLY SKULL NGC 246 in Cetus begins to resemble its skeletal nickname when imaged with large telescopes. S INTERSTELLAR FELINE Short exposures of the bright planetary NGC 6543 show why it's called the Cat's Eye Nebula. Spending more time on it will reveal its exceedingly faint, complex outer extent. sk yandtelescope.org * FEBRUARY 2 021 23http://www.skyandtelescope.org