December Gems in Cassiopeia
The Christmas season is upon us. Others may hear the jolly sound of Santa toting up the cash-register receipts. All I can hear is the wailing and gnashing of teeth as folks learn to use their new telescopes.
You know you really bought the telescope for yourself. Besides, how many seven-year-old telescope recipients know how to find Saturn? So do yourself a favor. As I have suggested in previous columns, purchase a good set of star charts for yourself. Also, buy “Jimmy’s” telescope before Christmas, take it outside, and learn to find a few objects. After Christmas, Jimmy will think you’re an astronerd of the highest order, and you won’t spend most of January wondering why you blew all that money on the blessed thing.
After you’ve seen the moon and Jupiter, a good place to go next is the large number of star clusters in the constellation Cassiopeia. Some of them look good in even small telescopes, and they’re relatively easy to find.
First, some background. Star clusters are collections of stars of about the same age. The stars are all relatively close together in space because they were born out of the same cloud of hydrogen gas.
The stars of a cluster are only loosely connected together by their mutual gravitational attraction. As a result, they are slowly drifting apart. Eventually, they will travel away from each other into the Milky Way galaxy. In the meantime, these mostly young stars are visible in the same low-power telescope field.
A mere few million years will pass before they aren’t clusters any more. Check them out before it’s too late.
The showpiece of the area is probably the Double Cluster, two star clusters that fit nicely in the same medium-power telescope field. It looks like two piles of glowing gems stacked up next to each other.
Next, look for NGC 663. You’ll see over a dozen bright, yellow stars surrounded by a haze of light. The haze consists of the unresolved glow of many other stars that your ‘scope is too small to see.
My personal favorite is NGC 7789, but I get to use telescopes as big as corn silos. In a larger ‘scope, you’ll see at least 100 stars surrounded by the same fuzzy glow as NGC 663. In a smaller ‘scope, the cluster looks like a ball of light with no individual stars visible.
NGC 7789 is huge, over 40 light years wide, and it’s far away at 5,000 light years. Remember, one light year is equal to about six trillion miles. No wonder this ball of 1,000 or so stars doesn’t resolve very well.
M 52 is one of the prettiest clusters in the constellation. You’ll see a few bright stars, but even in a small ‘scope, the background haze looks lumpy and rich, as if dozens of stars are just on the verge of popping out of the haze.
NGC 457 is far away at 9,000 light years. You’ll see a hazy, elongated glow with a few bright stars.
The brightest of the stars, called Phi, generates a considerable amount of controversy among astronomers. Because it is so much brighter than the other stars, you might assume that it is not really a part of the cluster and that it is much closer than the rest of the stars.
However, it appears to be moving through space at the same velocity as the rest of the cluster. If it really is at the same distance, it must be producing a whole lot of energy. In fact, it must be 250,000 times brighter than the sun, making it one of the most energetic stars known.
Stars like Phi are called supergiants — dying stars going through a burst of energy before they finally kick the comic bucket.
You’ll find a lot more clusters. Explore, enjoy, and put that new telescope through its paces.
If all else fails, you can always observe …
Blazing Venus is low in the southwest during evening twilight. You’ll need a clean horizon to see it as a small, white dot.
upiter is high in the southeast just after dark. Observe its four brightest moons in binoculars and its cloud bands and moons in a small telescope.
Mars is high in the ESE by 4 a.m. as an orange point of light. Telescopically, it’s a tiny orange dot and hardly worth a look.
Saturn is always worth a look. To the unaided eye, it looks like a pale yellow star low in the ESE at about 5:30 a.m. Even a small telescope will reveal its jaw-dropping rings.
Tom Burns is director of Ohio Wesleyan University’s Perkins Observatory in Delaware, Ohio. firstname.lastname@example.org