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Trifid Nebula (M20)
James Eugene Los

Trifid Nebula (M20)

The image above was taken of the Trifid Nebula, also known as Messier Object M20. Nebulae are huge clouds of interstellar gas, scattered across the sky. Charles Messier discovered the Trifid Nebula on June 5, 1764, and he described it as a cluster of stars of 8th to 9th magnitude. M20 is a part of the constelation Sagittarius, and is made up of a conspicious emission nebula and a reflection nebula.

This image of the Trifid Nebula emphasizes the distinct red emission nebula and captures part of the surrounding, blue reflection nebula, particularly visible on the northern end. The red color of emission nebulas are the result immense congregations of hydrogen gas being exctied by a newly formed, bright star. This bright star was formed out of the mass of hydrogen, and it can be clearly seen in this image. The blue color in the reflection nebula is the reflection of the star's light off huge amounts of dust. This image also shows the dark nebulae in the Trifid, where dark interstellar clouds block the emission and reflection light. M20 exists approximately 5200 lightyears from earth (Archinal et. al. 2011). Using this distance and the angular size of M20 in the image, the calculated linear size of the Trifid Nebula is approximately 27 lightyears. This image captures the beautifully brilliant features of this distant nebula.


Archinal, Brent A., and Steven W. Hynes. Messier Object 20. SEDS, 13 Aug. 2007. Web. 12 Apr. 2011. <>.

Slater, Timothy F., and Roger A. Freedman. Investigating Astronomy. New York: W. H. Freeman and Company, n.d. 5. Print.

Right Ascension (J2000) 18:02:18
Declination (J2000) -23:02:00
Filters used B (Blue), C (Clear), R (Red), V (Green)
Exposure time per filter B, C, and R (60s x 5); V (60s x 4)
Date observed March 28, 2011 11:49 PM UT



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