Western Slope Skies - The Significance of the Summer Triangle
A triangle of three bright stars has been noted throughout human history.
Are there events in your life that hold special significance for you? Maybe a birthday, graduation, or wedding comes to mind. Additionally, perhaps you marked these events with celebrations. Parties, receptions, and gatherings, big and small, are a way to help commemorate these events with those closest to you.
Summer is a popular time for weddings and graduations. It also has plenty of events of public significance as well. For example, while a somber day of remembrance, Memorial Day can also be associated with the unofficial start of the summer holiday season. Fourth of July is sometimes cause for fireworks to sparkle across the night sky.
Fireworks are not the only thing lighting up the darkness. Astronomically, there are significant happenings that occur at this time of year. The Milky Way is making its arc across the heavens at night. The current dark moon period gives you a perfect opportunity to view the dazzling lights that make up a part of our galaxy. A triangle of bright stars frames a portion of the Milky Way. This asterism is known as the Summer Triangle. These three stars pack quite the punch, calling attention to themselves throughout human history.
They are the brightest stars of each of their constellations. Look to Vega, the highest point of the triangle rising out of the east. In about 13,000 years from now, Vega will take the reins as the North Star. At the northeastern apex of the triangle is Deneb. While about 2000 light years distant, Deneb is a supergiant star, about 200 times the diameter of our sun. If placed where the sun is, Deneb would extend to earth’s orbit. The southern apex of the triangle is Altair, sitting at 16.6 lightyears away. This star rotates on its axis much faster than the sun, averaging over 120 miles per second.
This triangle provides guidance in the darkness. The United States Air Force nicknamed this asterism the “Navigator’s Triangle.” They relied on this collection of stars before electronic and mechanical navigational equipment. The northern Polynesian people called Vega the “year star.” Seeing it marked the beginning of the new planting season and ushered in the need to prepare the ground for agriculture.
The stars also play a significant role in mythology. For example, in Chinese mythology, Vega is a part of a constellation that represents a beautiful, weaving maiden. She fell in love with a poor cowherd, represented by a constellation that includes Altair. Their forbidden love caused them to be banished to opposite sides of the Milky Way. Deneb is a star that marks the beginning of a magpie bridge for the weaving girl and her lover to cross that celestial sea to spend the night together.
Many summer celebrations may include evening fires, fireworks, or other ways to light up the night. Alternatively, the Summer Triangle highlights the necessity of dark skies. One possibility is to go to an International Dark Sky Park to observe the bright Summer Triangle in its full glory. On a clear night, you can make out these three bright stars and the Milky Way. Take in the stars that surround this asterism. What shapes, animals, or stories do you see? Maybe the Summer Triangle can commemorate a special event of your own.
Western Slope Skies is produced by members of the Black Canyon Astronomical Society and KVNF Community Radio. This episode was written and recorded by Hannah Ashley, Park Ranger at Black Canyon of the Gunnison National Park.