By Bryan Shumaker
NASA/JPL Solar System Ambassador
Greetings yet again, my fellow sky lovers!
Needless to say, the weather has not been very cooperative the last several weeks.
It’s a small price to pay for the beauty of northern Michigan.
Still, perhaps it will clear for at least a few days.
Hope springs eternal!
The moon is Full on January 15. As usual, we will have to wait a few days for the waning moon to let us see the night sky, if only for a short time.
If you read last week’s column, we talked a bit about black holes—stars that are at least 8 times more massive than our own Sun will undergo a violent supernova explosion and collapse to form a black hole.
But what about stars like our own Sun?
They are destined to gradually use up their hydrogen by fusing it into helium (nuclear fusion).
After another 4 billion years or so (it has already been shining for about 5 billion years), most of the hydrogen will be used up.
The Sun will gradually swell to a size so large it will engulf the earth as it starts to fuse heavier and heavier elements.
Large amounts of solar material will be “puffed off” into space, until the small, very dense core remains.
Called a white dwarf, the core is not much larger than the earth, but extremely dense.
One teaspoon of a white dwarf weighs many tons!
Eventually all nuclear fusion stops, and the core gradually turns into a cold, dark cinder.
The puffed off gas often appears as a lovely ring or geometric shape.
It glows due to the intense radiation from the now tiny, exposed hot stellar core.
I thought it reasonable to talk a bit about some of the star chart nomenclature.
If you use any sky chart, it will have lots of letters and number designations by the different stars and celestial objects.
Probably the best known are objects that are prefixed with the letter “M” and a number after it.
The “M” stands for Charles Messier, an 18th century astronomer whose chief concern was finding and tracking comets.
He noticed with his modest, rather primitive telescope, little patches and clusters of light and stars which he might confuse with a comet.
Only after observing the same object several days in a row and finding there was no movement of the object would he realize it was NOT a comet at all.
He started a list of these objects to avoid confusion, which eventually had 110 different sky objects.
These are very useful for the amateur astronomer, because they are relatively easy to find and can be viewed with modest equipment, often even with binoculars.
Many of these objects have common names as well, such as M1, also known as the Crab Nebula. M13 is the Great Globular Cluster in Hercules, M42, the Orion Nebula, and so on.
These “M” objects are the easiest for amateurs to start with when observing.
Another list of designations is the “NGC” group.
This stands for “New Galactic Catalog” and has several thousand objects, many of them quite faint and small, all carefully cataloged. Many of the objects we see (including the “M” ones) ALSO have NGC designations; some objects may be listed in three or four different catalogs!
Stars are often shown with the designation “HP” (for Hipparchos).
Nebulae that glow on their own are in the “IC” catalog, and those that are dark, such as the famous Horsehead Nebula in Orion, are listed in the “B” catalog (named after E E Barnard, a famous American astronomer who many years ago listed them).
All of these database lists are on the internet, and most astronomy programs, including Stellarium (remember, FREE at www.stellarium.org for both Windows, Mac, and iPad), will be able to find the object if you put in one designation or another.
There are literally dozens of lists—The Herschel 400 catalog, the Caldwell catalog, etc.
Until next week, hope for clear skies, and keep looking up!