Take a trip across the north sky this autumn
Written by:
Greeley Wells
What I want to do in my column today is to take you on a journey across the night sky. Here we go!
So, looking north, we find the “W” of Cassiopeia almost perfectly upright. She can help us find Polaris, the North Star. Find the wider of the two “V’s” and divide it with your mind’s eye into thirds, using two lines that start from the bottom point of the V. Now follow the line next to the outside line, and it’ll take you to the North Star!
Now notice Cassiopeia’s husband, Cepheus, to her upper left, a bit above Polaris. He is a large, angled square connected to a triangle of three bright stars. The square and triangle make the shape of a house, pointing downish.
Overhead is the Summer Triangle, a bright threesome of stars, each of which is part of its own constellation. The lowest star is Deneb, which is also the star at the top of the Northern Cross.
Deneb and three other stars make the pole of the cross, with a star on either side forming the crosspiece, just where it should be! It’s also a perfect long necked swan! (This is why the Northern Cross is also called Cygnus, the Swan.)
The brightest star of the Summer Triangle is just to the west of the cross, and that’s Vega. Vega is a star in the constellation Lyra, an amazing two/two/two of stars very close to each other!
The third bright star in the Summer Triangle is Altair. She’s the middle star of a tight threesome, really cool, and so easy to see. Altair (Arabic for flying eagle) is part of the constellation Aquila the Eagle.
So there you go, we’ve made it across the sky from the North Star to the Summer Triangle. We’ve seen some great constellations along the way! But there are two little constellations we haven’t observed yet, tucked close to Altair. One is a little arrow: a tiny triangle at one end and two more stars making an arrow that points east. It’s small but obvious. East of the arrow is Delphinus the Dolphin. Four stars make a diamond-shaped body, with a more distant star as the tail. This is actually one of my all-time favorites!
Because all the stars (except for the North Star) are constantly moving, these constellations and stars we have been observing will be in the same position in exactly a year. You’ll notice all the stars except Polaris moving west, slowly but steadily, until next year when they will be in the same place as they are today
Of Note
Mercury is visible at dusk in September and October.
Venus is up in the evening, rising in October at dusk.
Jupiter and Mars are present in the mornings of September and October.
Greeley Wells
Image 1: Image: Sky & Telescope (skyandtelescope.org).
