The sky around Blue Snowball at true scale, north up and east left, with stars to magnitude 8. The circles show the field of a low-power eyepiece and of 10×50 binoculars.
Blue Snowball is a planetary nebula in Andromeda, 6,200 light-years away
Blue Snowball (Caldwell 22, NGC 7662, Herschel 400 no. 394) is a planetary nebula in the constellation Andromeda, 6,200 light-years away. It shines at magnitude 8.3 and spans 18″ of sky, about 0.5 light-years across. It is best in a small telescope, 4 to 6 inches, and it is highest in the evening sky in October.
Planetary nebula: a shell of gas thrown off by a dying Sun-like star and lit by the hot core left behind, which becomes a white dwarf. The name comes from their small, round, planet-like look in early telescopes.
Finding Blue Snowball from Alpheratz
Blue Snowball lies 15.9° northwest of Alpheratz, the magnitude 2.1 star. A fist held at arm's length covers about 10°.
Blue Snowball is highest in the evening in October
The chart gives its height above the horizon at 9 pm through the year, from 60°N to 40°S. It can be seen from the whole northern hemisphere and south to about 47°S, and never sets north of 47°N.
Blue Snowball is 6,200 light-years away
The light seen from Blue Snowball tonight left it about 6,200 years ago. It ranks 42 of 109 by distance among the 109 Caldwell objects. Distance source: Expansion distance 1.9 kpc, consistent with Gaia DR2 (Schonberner & Steffen 2019).
Objects within 6° of Blue Snowball
No other Messier, Caldwell or Herschel 400 object lies within 6°.
