Astronomy EssentialsClusters Nebulae Galaxies

See Messier 20, the Trifid Nebula

Chart showing the teapot and M8 and M20 above.
You’ll find M20 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 actually visible to the unaided eye on a dark, moonless night. Once you locate the Lagoon Nebula, look for the smaller 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. Here’s more about the Teapot.

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. 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.

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).

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

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. The Trifid and Lagoon Nebulae are a counterpart to another star-forming region on the opposite side of the sky: the Great Orion Nebula.

A billowing, colorful three-part cloud in space.
Trifid Nebula via the Hubble Space Telescope. Image via NASA/ESA.

The Trifid Nebula (M20) is at RA: 18h 02.6s; Dec: -23o 02′

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 still more.

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

Read more: M8 is the Lagoon Nebula

Read more: Exploring the Trifid Nebula

September 9, 2020
Astronomy Essentials

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