The Omega Nebula

M17, another vast region of interstellar gas and dust, is most commonly known as the Omega Nebula or the Swan Nebula. The complex measures 15 light-years across and is about 5,000 light-years from Earth.

M17, the Omega (or Swan) Nebula   (59 min total exposure Oct 13, 2023)

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Glowing hydrogen gas is the primary source of the nebula’s vibrant hues. Also visible are intricate filaments and tendrils of gas, woven like cosmic threads. The core of the nebula, where young, massive stars are born, appears as a concentrated brilliant region illuminating the surrounding nebulous material. The dark lanes and dusty regions within M17 contrast against the glowing background. They are potential sites for the formation of new stars.

IC4706 and IC4707 are small nebulae that are are actually part of the same nebular region as M17.

Why all the names?

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Messier 17 has been called at least five different names — Omega Nebula, Swan Nebula, Horseshoe Nebula, Checkmark Nebula and Lobster Nebula. Why so many?

Sir John Herschel in 1833 initially compared M17 to the capital Greek letter Omega, Ω. Using a telescope that turned the image upside down, his sketch showed something like an Ω with a long tail. Keep in mind that only the brightest part of the nebula is visible through a telescope. The fainter portions that you see in my long-exposure image are completley invisible visually. Herschel used the names Omega and Horseshoe interchangeably, and his sketches from the first half of the 19th century accentuate the horseshoe part of the nebula. The Greek letter Ω has the same shape as a horseshoe. Later observers tended to see a checkmark in the right half of the Ω and the longer tail extending the the right.

And finally the swan: If we rotate the image a little bit more we see the swan swimming peacefully to the left:

As to the Lobster, I am at a loss to see any resemblance. Perhaps the two sides of the Omega form the lobster’s claw?? Do you have any ideas?