Archive for January, 2011

The Great Orion Nebula

Monday, January 31st, 2011

While looking over what I’ve written about the sights enjoyed by amateur astronomers, I noticed a glaring omission. Somehow I haven’t mentioned M42, the Great Orion Nebula, among the most observed objects in the night sky. This diffuse nebula is among the brighest, and is even visible to the naked eye. M42 is estimated to be 24 light years across and is at a distance of about 1350 light years. Besides being a favorite sight for amateur astronomers, scientists are also interested in M42 as a region of stellar formation. An interesting bit of trivia is that in 1880 the Orion nebula became the first target of deep-sky astrophotography.

Finding the Orion Nebula could hardly be easier. Simply look to the “sword” below Orion’s belt. If you have a larger telescope and dark skies, there are plenty of other nebulae and interesting features within this area of Orion. But large telescope or small, the Orion nebula is always an enjoyable target.

The Winter Triangles?

Friday, January 21st, 2011

The Summer Triangle is the famous asterism formed by the stars Vega, Deneb and Altair. And while we enjoy it’s sights high overhead on warm summer nights, this time of year we have a double chance to take a look. Thanks to the long winter nights, the Summer Triangle is visible low in the west just after sunset. It’s also visible low in the east just before sunrise. So you can pick your time and enjoy some summer sights in the middle of winter.

Then, for the time in between, there’s the asterism that really is known as the Winter Triangle.  It’s corners are the bright stars Betelgeuse, Sirius and Procyon.  This triangle is visible in the southern sky all through these winter nights.

The Winter Crab

Monday, January 17th, 2011

Among the Messier Objects dotting the night sky, you will find numerous galaxies, planetary and diffuse nebulae, and open and globular star clusters. But M1, the Crab Nebula, is unique in being the only supernova remnant to make Messier’s list.  Created by a supernova observed by Chinese and Arab astronomers in 1054, the Crab Nebula itself was first observed in 1731.  Located at a distance of roughly 6500 light years, the nebula is expanding at a rate of 1500 km/s. This expansion was discovered in the early 20th century by comparing photographs of the nebula taken several years apart.

To see the Crab Nebula, you’ll need reasonably dark skies. At magnitude 8.4, it can be easily washed out by light pollution.  From my home on the edge of a mid-sized city, it’s just barely visible. But with dark enough skies, it makes a nice target for small telescopes. Located in the constellation Taurus, the easiest way to find the Crab Nebula is to start with the Hyades star cluster (the asterism known as the “head of the bull”). Follow the line formed by the “bottom” of the Hyades to find Zeta Taurii. Going up from there, the Crab Nebula can be easily found. Once the upcoming full moon gets out of the way, we’ll be moving into prime time to see this winter crab. (Does that make it a snow crab?)