Like so many of us, Charles Messier became interested in the universe, and especially our galaxy with all its bright celestial objects, as a youngster. (Lucky boy, not much light pollution in his time.) Charles carried this interest forward to become an astronomer in Paris, where, among many other accomplishments, he gained lasting recognition for his catalog of clusters, nebulae, and galaxies. That catalog is the “M” series of heavenly bodies, and it is still in use today.
Interestingly enough, Messier’s first passion was comets (he discovered 20) and yet, his catalog is a meticulously-recorded collection of other important celestial objects. These objects have come to be so well-known, in fact, that they are an integral part of Slooh’s own collection of regularly-featured targets.
Initially, Charles Messier was convinced that the first entry in his catalog, noted as M1, was a comet. But, as the world would eventually learn, M1 was not a comet at all. It is a nebula that evolved from a supernova observed some 950 years ago - or about 700 years before Messier discovered her. (I say “her” because I find this celestial wonder quite beautiful, entrancing, and definitely a bit mysterious.)
M1, the exotic Crab Nebula, was first observed and recorded as an actual supernova by Chinese astronomers in 1054. Additionally, petroglyphs from the Anasazi cliff dwellings in New Mexico and Arizona seem to indicate that they, too, sighted the supernova or, at least, were told about it and recorded it. And although Charles Messier’s independent discovery of the Crab Nebula gets most of the attention, it was actually John Bevis who first discovered and cataloged the object in 1731, twenty-seven years before Messier’s discovery.
Because of the vast distances of space, we witness events long after they actually occur. So, using my handy time/distance calculator and the Chinese year of discovery, I approximate that the M1 supernova occurred around 5000BC or about 6000+ years before the Chinese saw the event. SEDS reports the Crab Nebula’s distance as 6300 light years. You can try calculating this time interval yourself. Click on the time/distance link above to launch the calculator.
Enough history - lets talk about the Crab. First, here she is in all her glory, compliments of Slooh’s Teide 1 High-Mag telescope and the Slooh members.
I selected this image because it shows both the crab-like filaments of the nebula and her mighty pulsar. We will get to the pulsar below, but first some details about the Crab Nebula.
Because it resulted from a supernova (material is moving out and away,) the Crab is ever-expanding at the rate of 1800 km/sec. So, the Crab you view today will not be quite the same when your great-grandchildren view it. Meanwhile, as you look at the image of the nebula, you can, with some imagination, see her resemblance to a crab; but the real source of her name comes from an 1844 drawing by William Parsons, the Third Earl of Rosse. Go ahead and click on the link to see Lord Rosse’s drawing. You can see that it clearly resembles a horseshoe crab - a creature with its own prehistoric lineage.
The Crab Nebula is important for several key reasons. Her traceable history, from her explosive origins to what we see today, provides important data about the evolutionary processes that follow supernova events. Additionally, the 1968 discovery of the Crab Pulsar added another important research element to be studied. In fact, within professional astronomy circles, there is a rumored division between those who study the Crab Nebula and those who do not.
The Crab Pulsar is an amazing and powerful neutron star. Neutron stars evolve from stars that have masses 4 to 8 times greater than our sun. They are the products of supernovas and often remain as part of the remnants. Some neutron stars have fast-moving jets streaming out above their magnetic poles. These jets produce very powerful beams of light that sweep around as the star rotates. These sweeping beams are detected as varying radio frequencies or pulses; thus, we call these stars “radio pulsars.”
Pulsars are found both within and without supernovae remnants. When associated with a remnant, as is the Crab’s pulsar, the nebula is further categorized as a pulsar wind nebula. In fact, scientific data states that the Crab Nebula is much more a pulsar wind nebula than it is a supernova remnant; and because it was the first such object discovered, M1 is the prototype. Of the more than 1600 known radio pulsars, less than 40 are associated with nebulae. In the Slooh image above, you can see the Crab’s pulsar as that fuzzy star-like object directly beneath the nebula’s bright center region.
Fun Facts: * Neutron stars are so dense, just one teaspoonful would weigh one-billion tons on Earth. * The Crab Pulsar contains a mass equal to our sun crammed into an object just twelve miles wide. * The Crab Nebula measures 10 LY across - that’s 58.8 trillion miles or 94.6 trillion kilometers.
I could tell you much more about the Crab Nebula, but I’d rather encourage each of you to dig deeper on your own. You can start by observing the Crab Nebula, either through Slooh’s Editor Channel or by reserving a slot on the Member Channel. The Editor Channel schedule can be found here in the Slooh User Forums, and guidelines for reserving your own Member mission can be found here in the Slooh Help & FAQ. If you need direct assistance, simply pop into the Slooh ChatRoom where you can ask questions in real-time.
As a “Focus On” bonus, we’ll feature the Crab Nebula with a Slooh Mission Alert later this week. We’ll target it through the Slooh telescopes with three back-to-back missions and talk more about it with special commentary on SloohRadio. Watch the Launchpad banner or Slooh Twitter Feed for more details.
NOTE: Currently, a Mission Alert is scheduled for Thursday, Nov. 20, 8:30pm EST / 01:30 UTC - weather permitting.
NOTE: Thursday’s Mission Alert has been rescheduled to Saturday, Nov. 22, 8:30pm EST / 01:30 UTC - weather permitting.
Look up, always, and dark, clear skies for all. And don’t forget to check back next month for another installment of “Focus On.”
