SUMMERSIDE, P.E.I. – Hi sky friends. Here is something I bet you all know in our night sky – the Big Dipper.
Let’s start by talking about star shapes and star grouping. First, while we see many “shapes” in the heavens, these are entirely by chance, as stars lie in the sky. We humans tend to see shapes – to draw lines where there are actually none. This is the case with the Big Dipper.
The sky is technically divided into 88 constellations, which encompass the entire “globe” around our earth. These are divided by “picket fences” borders set up artificially by the astronomy professionals. The shapes that we see, such as the Big Dipper, are called Asterisms – shapes within a constellation or occasionally in more than one constellation.
The Big Dipper is a part of the larger Asterism, the Great Bear, within the constellation Ursa Major. The Big Dipper contains seven chief, easily seen stars in the shape so well known to most of us.
Let us look at a few of the interesting shapes and ideas in this Asterism.
Note that there are three stars in a curve that form the handle of the dipper. There are then four stars in the “pot”. Let’s start there.
If we look at the two outer stars of the pot – away from the handle – they are called pointers. This is what they do – point. If we go from the direction of the bottom of the pot to the top, take the distance between the two pointers and extend the pointer line five times that distance, we come to Polaris – the north star.
What is the importance of this? If we face in that direction, we are indeed looking north.
What next? If we go to the middle star of the handle, and if we have good – often young – vision, we will see that this is actually two stars, one above the other, and very close to each other. If you have difficulty seeing them separately, use binoculars.
In another article we will learn to tell time by the Big Dipper.
So as usual, what’s in the sky this month?
It depends if you are looking up early in the month or later.
Let’s start early in February. Well, it’s much like the last several months in that we will see Jupiter, Mars, and Saturn in the predawn sky. We have now lost Venus and Mercury because of their path before/behind the sun, but no fear, they will soon be back in our sky.
In the morning Jupiter rises first in the southeast appearing as early as 2 a.m. and ascending up and across the sky. Mars follows about one hour later and, finally, Saturn peaks its head up at about 5 a.m. All three rise earlier as the month passes.
Late in the month we can finally see planets in our night sky again. Watch after sunrise and by later in the month, we will begin to see brilliant Venus, and then almost at month’s end, Mercury will be seen just a little below Venus, but much dimmer. Binoculars will make it easier.
A special this month
There is lots of dust out in space, albeit quite spread out or thin. But this dust shows up in the evening sky after dark. It’s like a gauzy cone of light – like a skewed triangle. Look in the west. It is best in February and March, but only if the moon is out of the sky. So for February, this is happening Feb. 2 to 16. We will note this again in March.
Well, that is it again, my sky friends. See you in March.
Dr. Rolly Chiasson of Summerside is "Your Sky Guy," who writes monthly astronomy columns for the Journal Pioneer.