A Sagittarius Triplet
From
NASA’s Astronomy
Picture of the Day
These three bright
nebulae are often featured in telescopic tours of the constellation Sagittarius and the
crowded starfields of the central
Milky Way.
In fact, 18th century cosmic tourist Charles Messier cataloged
two of them; M8, the large nebula left of center, and colorful M20 on the
right.
The third, NGC 6559, is above M8,
separated from the larger nebula by a dark dust lane. All three are stellar
nurseries about five thousand light-years or so distant. The expansive M8, over
a hundred light-years across, is also known as the Lagoon Nebula.
M20's popular moniker is the Trifid. Glowing hydrogen
gas creates the dominant red color of the emission nebulae, with contrasting
blue hues, most striking in the Trifid, due to dust reflected starlight. The colorful skyscape recorded
with telescope and digital camera also includes one of Messier's open star
clusters, M21, just
above the Trifid.
Image Credit & Copyright: Tony Hallas
