Astronomy EssentialsClusters Nebulae Galaxies

See Messier 20, the Trifid Nebula

The Trifid Nebula Chart showing the teapot and M8 and M20 above.
You’ll find M20, the Trifid Nebula, in a dark sky near the spout of the Teapot in Sagittarius. Notice the 3 westernmost (right-hand) stars of the Teapot spout, then get ready to star-hop! Use binoculars and go about twice the spout’s distance upward until a bright hazy object glares at you in your binoculars. That’s the Lagoon Nebula (Messier 8), which is visible to the unaided eye on a dark, moonless night. Once you locate the Lagoon Nebula, look for the Trifid Nebula as a hazy object some 2 degrees above the Lagoon. For reference, keep in mind that a binocular field commonly spans 5 to 6 degrees of sky. Image via EarthSky.

The Trifid Nebula

The Trifid Nebula (Messier 20 or M20) is one of the many binocular treasures in the direction of the center of our Milky Way galaxy. In fact, its name means divided into three lobes, although you’ll likely need a telescope to see why. On a dark, moonless night – from a rural location – you can star-hop upward from the spout of the Teapot in Sagittarius to another famous nebula, the Lagoon, also known as Messier 8. In the same binocular field, look for the smaller and fainter Trifid Nebula as a fuzzy patch above the Lagoon.

Green and orange clouds in a starry sky.
Visible light pictures show the nebula divided into 3 parts by dark, obscuring dust lanes, but this penetrating infrared image by the Spitzer Space Telescope reveals filaments of luminous gas and newborn stars. Image via APOD/ JPL-Caltech/ J. Rho (SSC/Caltech).

Locating the Trifid Nebula

To locate this nebula, first find the famous Teapot asterism in the western half of Sagittarius. The Teapot is just a star pattern, not an entire constellation. Nonetheless, most people have an easier time envisioning the Teapot than the Centaur that Sagittarius is supposed to represent. How can you find it? First, be sure you’re looking on a dark night, from a rural location.

Then, look southward in the evening from Earth’s Northern Hemisphere. If you’re in Earth’s Southern Hemisphere, look northward, closer to overhead, and turn the charts below upside down. Want a more exact location for the Teapot in Sagittarius? We hear good things about Stellarium, which will let you set a date and time from your exact location on the globe.

Chart with very many stars, outlines of constellations, and other objects marked.
Chart showing one of the most star-rich regions of the Milky Way galaxy, toward the galaxy’s center, in the direction of the constellation Sagittarius. If you look closely, you can pick out M20 on this chart. Chart via astronomy.com.

The Lagoon Nebula

Whether the close-knit nebulosity of the Trifid and the Lagoon represents a chance alignment or an actual kinship between the two nebulae is open to question. Both the Trifid and Lagoon are thought to reside about 5,000 light-years away, suggesting the possibility of a common origin. But these distances are not known with precision, and may be subject to revision.

Both the Trifid and Lagoon are vast cocoons of interstellar dust and gas. These are stellar nurseries, actively giving birth to new stars. By the way, the Trifid and Lagoon Nebulae are a counterpart to another star-forming region on the opposite side of the sky: the Great Orion Nebula.

Very dense star field with pink blob near bottom and blue and pink upper right.
View at EarthSky Community Photos. | Ken Chan in Portola Valley, California, captured this photo of the Trifid Nebula (top) and Lagoon Nebula (bottom) on August 7, 2021. Thank you, Ken!

Bottom line: The Trifid nebula (M20) is located in the direction of the center of the Milky Way galaxy. If you have an extremely dark sky, you can see the nebula on a moonless night as a fuzzy patch in the Milky Way. Binoculars show more and a telescope reveals even more detail.

Read more: Find the Teapot, and look toward the galaxy’s center

Read more: M8 is the Lagoon Nebula

Posted 
August 17, 2022
 in 
Astronomy Essentials

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