Thursday, July 11, 2013

The Summer Triangle

One of my favorite asterisms is the Summer Triangle.

But wait! One might ask, '"What's an asterism?"    

An asterism is what is most people mean when they say "constellation". It is pattern in the sky made by stars. A constellation, in the astronomical usage of the word, is a region of the sky. Constellations contain asterisms but also galaxies, nebulae, star clusters, and much more.

The Summer Triangle is an asterism comprised of three bright stars
Credit: Flicker user Charles de Mille-Isles
The Summer Triangle is an asterism comprised of three bright stars, each in three different constellations: Deneb, in Cygnus; Vega, in Lyra, and Altair, in Aquila. Although it is visible in the spring and autumn, in the Northern Hemisphere, these stars are visible near the zenith (the region of the sky directly overhead) throughout the night during the summer, hence the name. My affection for the Summer Triangle lies in memories of evenings spent with my family looking up at the stars in my front yard. Even in a suburban neighborhood littered (I choose that word carefully) with torch-like security lights, the Summer Triangle shines brightly in the sky. 

For the next three weeks, I plan on featuring each of the stars in the Summer Triangle. I'll begin this week with Deneb, located in Cygnus, "The Swan", the brightest stars of which form another asterism, "The Northern Cross". In fact, I can hardly think the name "Deneb" without the image of a swan popping in my mind. 

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