This time of year, as winter approaches, the summer constellations set in the west as the winter stars rise in the east. Before modern methods of time keeping, the sky was the first calendar. It told early farmers when to plant, harvest, and to prepare for the coming changes in weather. It told hunter-gatherers when to expect animal migrations, or when native plants would bear fruit.
I’ve attached a ‘farewell until next year’ picture of the summer constellation Cygnus, also known as the Northern Cross. The Northern Cross can be found in the west after dark. The bright star Deneb marks the head of the cross. The star Deneb is 20 times heavier, and over 200 times larger than our star, the Sun.
I’ve put in constellation lines to help visualize the Northern Cross. This is a 2 minute exposure photograph, tracking the Earth’s rotation. It shows many more stars than would normally be seen just looking up with the naked eye.
You may notice the photo looks cloudy or foggy. This foggy appearance is not caused by clouds, but from countless background stars. Our Milky Way galaxy runs through the constellation Cygnus from right to left. The result is a high concentration of stars and nebulae. In fact, where you see gaps in the stars the gaps are not an absence of stars, but the result of dark nebulae in the foreground blocking the more distant stars from view.
Just as Galileo found when he first pointed a telescope toward that milky band of light in the sky some 400 plus years ago, we too find it is composed of billions of stars that make up our Milky Way Galaxy.
