SUNSET: 
0
Photographer:
Andreaiorio
Location of Photo:
Marino, Rome, Italy
Date/Time of photo:
12/03/2024
Equipment:
ZWO ASI533MC Pro, ZWO OAG & ASI 120MM, Skywatcher 130PDS f5, Tecnosky 60ED APO, ZWO ASI 715MC, Skywatcher EQM-35 Pro
Description:
Although Abell 21, or Sh2-274, has a large apparent diameter of 10 arcminutes, its surface brightness is so low, with features ranging from magnitude 16-25, that it was not discovered until 1955. It is a planetary nebula lying at a distance of 1,500 light-years in the constellation Gemini, which gives it an estimated diameter of 4 light-years. The parent star, now a white dwarf, is thought to be the deep blue star near the center of the nebula.
