More Backyard Astronomy 2/18/2021. Today I'm working on The Crab Nebula. Astronomers list it in their catalogs of stars and other objects in space as Messier 1, M1, NGC 1952, and Taurus A. When stars blow up, like a nuclear explosion in space, we call it a nova or a supernova if gigantic. They slough off their gas which will often glow, like a neon light, from the energy in the ultraviolet light from nearby stars.

This glowing gas often flows into beautiful formations which we call a nebula, like the photo I posted today. This type of nebula is called a supernova remnant.

What remains of the star besides the nebula is a pulsar, a pulsating star made up almost entirely of neutrons, the nucleus of the atoms. This Crab Nebula is found in the constellation of Taurus. I've known a few crabby people born under that sign. However, the crab name comes from a drawing an early astronomer drew which looked like a crab.

This supernova was documented by the Chinese in 1054 a.d. It was said that the supernova could be seen in broad daylight! The nebula lies in the Perseus Arm of our own Milky Way galaxy, at a distance of about 6,500 ly from Earth. LY stands for a light year or the distance light travels in a period of one year. How far is that? About 6 trillion miles or a mile for every dollar our government spends in a year.

The Crab has a diameter of 11 light years. So, traveling at the speed of light, it would take you eleven years to travel from one end to the other. The expanding gas is being propelled by the shock wave from the initial explosion and is expanding at about 930 miles per second. That speed is nearly as fast as a toilet paper shopper traveled to the shopping warehouse when a load of toilet paper arrived at the store early in the pandemic.

At the center of the Crab Nebula lies the Crab Pulsar. The spinning neutron star is less than 20 miles in diameter and spins 30 times a second. It emits pulses of radiation from gamma rays to radio waves. The Crab Nebula is generally the brightest persistent gamma-ray source in the sky.

For my friends who are into astrophotography, I photographed the Crab Nebula with my Meade LX200 ACF 14" Schmidt Cassegrain telescope using an ASI2600MC Pro one shot color camera and an Optolong Lenhance Ha and Ox3 filter. The photo is not enlarged as I used the telescope's full 3556 mm focal length unreduced at F10. It is comprised of 86 five minute exposures at a gain of 100 for a total of 7.16 hours of exposures. I autoguide with an off axis guider and a Starlight Express Lodestar II camera using the software PHD2. The photo was processed using Startools Version 1.7.457.

I am grateful for help from my wife Elizabeth, who puts up with me, for the color correction, as I am badly colorblind. Thanks Liz. Hope you enjoy this version of the Crab Nebula.