Messier Monday: The Crab Nebula, M1 [Starts With A Bang]

“This nebula had such a resemblance to a comet in its form and brightness that I endeavored to find others, so that astronomers would not confuse these same nebulae with comets just beginning to shine.” -Charles Messier

Let’s take a journey back in time to when our known Universe was a lot smaller. The only planets discovered were Mercury through Saturn: the naked eye planets. The well-known objects were our Moon, the (naked-eye) planets and their moons, and the stars and the Sun. After those, the only new objects that were routinely hunted in the night sky were those two-tailed recurring wonders: the comets!

Other objects were known, such as novae and supernovae, but comet discovery was the primary goal of most astronomers of the day. In 1758, Charles Messier was no different, as he was eagerly anticipating the return of Halley’s Comet, predicted by Halley himself to return in that year.

So you can imagine Messier’s excitement when he looked through his large (for the time) telescope, and saw — on September 12^th of that year — something much like this.

The bright star itself isn’t interesting, but that nebulous blob above and to the left of it sure looked like the early stages of a brightening, returning comet to Messier! But, alas, this was no comet, as it neither brightened nor changed position nor altered in appearance over the subsequent nights.

Messier quickly realized that he was looking not at a comet, but at a much more permanent nebula in the night sky — a faint, extended object — that could be easily confused with a comet by someone who didn’t know about its existence. And so began the Messier Catalog, a list of (eventually) 110 objects that would frustrate unsuspecting comet-hunters.

But each object in the catalog, containing not a single comet, has a remarkable story in its own right. Each Monday — starting today, the first “Messier Monday” — I’ll be highlighting one of these Messier objects, visible through small telescopes (or binoculars) under good conditions, for you. (And we won’t be going in order, so if you’ve got a favorite, let me know!)

To begin, here’s how you find Messier 1, also known as the Crab Nebula.

Tonight, if you step outside, the great constellation Orion should rise shortly after sunset. Many degrees above the top two stars — Betelgeuse and Bellatrix — but not quite as far as the very bright Alnath (or the planet Jupiter), you’ll find a modestly bright star known as ζ Tauri, a 3rd magnitude star visible even within most cities on a clear night.

And if you point a good pair of binocular at ζ Tauri (under dark skies), here’s what you’re likely to see.

Among the bright stars, ranging from a deep orange to a bright blue in color, you’ll find an unmistakably distended, faint, and fuzzy object. That’s the Crab Nebula, or Messier 1.

Even in the hands of an amateur with an excellent quality telescope-and-camera, the level of detail that can be teased out of this object is breathtaking.

What you’re looking at is a star within our galaxy that died very recently: in 1054, to be precise! Since then, the supernova remnant has been expanding into the space surrounding it, creating the Messier object we know today as M1: the Crab Nebula.

And this spectacular object continues to evolve over time, as these two images — from 1973 and 2000 — demonstrate.

While the outer layers of this dead star continue to expand and cool, the inner core has collapsed into a pulsing, X-ray emitting neutron star, spectacularly visible to a space telescope like Chandra.

In fact, the pulsar — spinning and pulsing some 30 times per second – changes over time, as this seven-month timelapse video from the same Chandra team shows!

But, by far, the best view of this supernova remnant comes from the incomparable Hubble Space Telescope, which truly captures the detail of the expanding, filamentary structure from the outer layers of this dead star interacting with the interstellar medium.

Although this image is an enhanced-color composite and mosaic (many images stitched together), the filamentary structure is real, as this detailed close-up illustrates.

This supernova remnant may yet trigger the formation of new stars as it continues to expand and interact with molecular clouds, while the inner neutron star will continue to change over time, as its environment is far from being in equilibrium.

Don’t believe that last part? Take a look at the Hubble close-up of the inner region, taken just months apart back in the 1990s, of the space around the pulsar itself!

This object — the very first Messier object — continues to evolve over time, and will achieve its 1,000-year anniversary, as best as we can tell, in July of 2054.

Enjoy the very first Messier Monday; it won’t be your last!

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