Source: The Herald, June 16, 2013
This coming week is the swan song for spring 2013 in the Northwest skies as summer officially begins at 10:04 p.m.Thursday.
The bad or good news, depending on your perspective, is that we start losing daylight and gaining stargazing time.
Once it finally gets dark, what’s left of the spring constellations are hanging in the western sky. The spring constellations are not exactly celestial barnburners.
Constellations like Cancer the Crab, Corvis the Crow, and Coma Berenices the Cut Hair don’t exactly make the highlight film for backyard astronomers.
Leo the Lion is a little better. That’s the constellation that looks like a rightward leaning, backward question mark in the western sky after evening twilight.
The moderately bright star at the bottom of the leaning question mark depicts the lion’s heart. The rest of the cycle outlines the head of the beast. In about another month we’ll lose the Lion in the twilight as Earth turns away from that part of space in its orbit around the sun.
In the eastern sky right now the stars and constellations of summer are on the rise and from night to night and week-to-week, they’ll start out the evening higher in the sky as darkness sets in.
Among them are the three bright stars that make up what’s known as the “Summer Triangle” that’s very easy to find.
Simply look in the northeastern quarter of the sky for the three brightest stars you can see and that’s it. This triad of stars is one of the best tools for getting around the summer sky because each of the stars is the brightest member in it’s respective constellation.
The highest and brightest is Vega in the constellation Lyra the Harp. The second brightest star is Altair on the lower right side of the triangle that is also the brightest luminary in Aquila the Eagle.
The third brightest on the lower left corner of the triangle is Deneb, brightest star in Cygnus the Swan, also known by its nickname the Northern Cross.
Deneb is the dimmest of the Summer Triangle as we see it, it’s the biggest and most powerful of the three stars.
Its diameter is a little more than 200 times that of our sun, which would give it a girth of 150 to 200 million miles.
Deneb is the faintest stellar member of the Summer Triangle because of its immense distance. It emanates from more than 1,500 light-years away. Just one light-year, the distance that light travel in year’s time equals just under 6 trillion miles.
In miles that would make Deneb 8,700 trillion miles away.
As far away as Deneb is it’s still a fair close-by star in our home Milky Way Galaxy that that stretches more than a 100,000 light-years in diameter.
Don’t ever forget the vastness of what you’re peering into when you spend a summer night under the stars.
Mike Lynch is an astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis.