January 2019

Dear Friends of Lookout Observatory,

Scientists love to classify things and make catalogs of their observations. One of astronomy’s earliest catalogs still in use today was created by a Frenchman named Charles Messier starting in 1760. He liked to search for comets, but he kept finding fuzzy objects that looked like comets in his small telescope but didn’t move relative to the stars, so couldn’t be comets. He made a listing of these fuzzy objects so he wouldn’t be misled in his comet searches. These fuzzy objects are called “deep sky objects” today, and they consist of galaxies, gaseous nebulae, and clusters of stars. Since his telescope was small, the fact that he could see them at all means that they are some of the brightest and most interesting deep sky objects that astronomers love to look at. They are identified as M (for Messier) followed by a number. So the first object he listed is M1, and a few were added after his death so that the last one is M110. The famous galaxy in Andromeda is known as M32. Since then many other catalogs have been published, such as the New General Catalog in 1888 listing nearly 8000 deep sky objects. The Andromeda Galaxy in that catalog is NGC 224. Modern astronomers have many large specialized catalogs such as the Principal Galaxy Catalog (PGC), which contains hundreds of thousands of galaxies.

But to return to Messier’s catalog, I have a special fondness for his very first one, M1. It is otherwise known as the Crab Nebula, and it is a supernova remnant, the gaseous shell of a star that blew its outer part away, leaving only a super dense neutron star core at the center. In 1054 AD Chinese astronomers observed a bright “new star,” brighter than any other star in the night sky, that gradually faded over two years. It is now known that this was the initial explosion that started the expansion of the Crab Nebula, and it is the first astronomical object ever to be linked to an historical supernova observation.

What is my personal connection? Well, nearly 34 years ago when Anitra was pregnant with our second child, we decided to search for a larger house. After many false starts we finally found a house we loved and thought we could afford, but there were two better offers ahead of us. But by some miracle both offers eventually proved not workable, and we got the house. I knew this house was meant for us because its address is 1054, the year when M1 began it’s explosion! And we are still living in that house.

This time of year it is too cold to take pictures at Lookout Observatory, so I take pictures from the Southern Outpost of Lookout Observatory, otherwise known as our back yard in Albany, CA, where it is much warmer. So below is a picture of M1 taken from our “M1 house.”

With lots of light pollution in the San Francisco Bay Area, astronomical imaging can be difficult, but modern specialized photographic filters can do wonders, so this 60-minute time exposure taken through an 8-inch diameter telescope shows quite a bit of detail. This object is about 6,500 light years away and about 13 light years across – a size it has expanded to in less than 1000 years. That’s about 900 miles of travel each second!

The brightest part of the bluish nebulosity at the center is arc shaped. If you look just to the left of it and down slightly, you will see two stars very close together. The fainter (smaller) one is below and to the right of the brighter one. This fainter one is the pulsar, a rapidly spinning (30 times a second) neutron star – all that remains after blowing off its great shell of expanding gas. The most striking part of the blown-off atmosphere of the original star is the reddish filaments of hydrogen and other elements. Their exact nature is poorly understood. The bluish color is produced by electrons moving at up to half the speed of light in the powerful magnetic field created by a pulsar — called synchroton radiation. This unique nebula is of great interest to professional astronomers, partly because the complex physical forces operating within it are so powerful that changes in its core can be observed in just a few days.

Keep looking up,

Carter Mehl, Lookout Observatory