The Coalsack is probably the most prominent the dark nebulae visible to the naked eye. It casts a dark silhouette against the Milky Way’s bright stripe of stars in the southern sky. The Coalsack is located roughly 600 light-years away in the southern part of the constellation of Crux (the Southern Cross).
This apparently starless dark patch is really an opaque cloud of interstellar dust blocking the light from the background stars. Dust grains in the cloud redden the starlight that reaches us by absorbing blue light preferentially, so that the red stars shimmering in the northern and darkest part of the Coalsack appear deeper red than they would in the absence of this dust.
This is NGC 6535, a globular cluster 22,000 light-years away in the constellation of Serpens (The Serpent). It’s about one light-year across.
Globular clusters are tightly bound groups of stars which orbit galaxies. The Latin word globulus, from which these clusters take their name, means a small sphere. A large mass in the rich stellar centre of a globular cluster pulls the stars inward to form a ball of stars.
Globular clusters are generally very ancient objects that form around the same time as their host galaxy. Thus far, no new star formation has been observed within amy globular cluster. The lack of young stars explains the abundance of aging yellow stars in this image, most of them containing very few heavy elements.
EXECUTIVE PRODUCER: (Telephone Filter) Good morning, Johnny. How was the the fishing up north.
JOHNNY: Cold, but good. What’s up?
EXECUTIVE PRODUCER: (Telephone Filter) I want to do a year-in-review show.
JOHNNY: Uh, huh.
EXECUTIVE PRODUCER: (Telephone Filter) Go through the cases and pick out the best two or three shows.
JOHNNY: OK. I’ll take a look.
MUSIC: Theme up and under.
ANNOUNCER: The Lickspittle Broadcasting System presents W. J. J. Hoge in the transcribed adventures of the man with the action-packed Twitter account, America’s fabulous free-lance Internet investigator …