Summer Ascends In The East At Nightfall

A nearly full moon casts my shadow on a road in Duluth. Man, is my head small! Bob King

The moon’s waxing brighter now. I notice the change in the intensity of its light during my nightly walks. Under a thin crescent, my shadow is dim and lean, but by half-moon dark and distinct. A half-moon also provides enough light to read the landscape and see the creatures of the night like deer and skunks. I really like seeing skunks before I meet them.

As the moon brightens it also makes the sky grow paler and diminishes the both the brilliance and number of stars we see. That’s because the air diffuses and scatter moonlight across the entire sky. But no matter the lunar phase the brightest stars always push through even in washed-out skies.

Find a place with a good eastern exposure to see and appreciate one the biggest patterns in the sky — the Summer Triangle. Each bright star in the Triangle heads up a constellation. The Northern Cross is actually a swan called Cygnus with Deneb marking the fowl’s tail. Lyra is a small harp called a lyre. Stellarium

Three of them now join forces in the east to vie for your attention: Vega, Deneb and Altair. You probably already know them as the Summer Triangle asterism. The Summer Triangle is nearly as obvious as Orion’s Belt and just like it offers a good jumping-off place to find other stars and constellations.

Vega’s up first, a bright, white, scintillating sun visible low in the northeastern sky at first darkness. Vega heads up the constellation Lyra the harp. Deneb, the brightest star in the Cygnus the swan (a.k.a. Northern Cross) comes next followed later by Altair in Aquila the eagle. Connect the three bright dots and you’ll make a giant triangle about two fists wide along the top, three along the right (western) side and almost four fists along the left (eastern) side.

I took this photo last Friday night in moonlight. Can you spot the Summer Triangle? The Milky Way shows faintly from upper left to lower right. Bob King

Twilight lingers long come mid-May. Once it ends, so long as you have a clear view down near the eastern horizon, you’ll spot Altair, the last of the trio to rise. The three great stars and the fat slice of Milky Way they enclose rise above a landscape ripening toward summer. Not only the frogs and the occasional owl hoot but the ground itself trembles with life as plants push up through the detritus of last fall. If you’re in a quiet place bend an ear ground-ward and listen carefully for the rustle of violets and bluebells in search of sunlight even in the dead of night.

In this map I’ve highlighted two bright double stars for binoculars. Epsilon Lyrae (top) is an easy split in any pair. Through a small telescope at around 150x each of the two stars is double again. Albireo (al-BEER-ee-oh) is more challenging to split. I’ve seen the fainter companion (to the lower left of the main star) in 8x binoculars, but 10x will make it easier. Try to hold them as steady as you can! A small telescope will show the stars’ contrasting colors. Stellarium

For the moment, the moon interferes with seeing the Milky Way, but once it departs the evening sky after full (May 18), we’ll get a great view of the central plane of our galaxy (that’s what the Milky Way band is) rising in the eastern sky. For people who’ve never seen the Milky Way it can look like clouds moving in on an east wind. In a sense, it is a cloud but one made of billions of stars seen from far, far away.

While you’re waiting for dark skies, venture out the next clear night to see if you can find the Summer Triangle. Once in sight, I encourage you to use binoculars to observe two prominent double stars in the region — Albireo, also known as Beta (β) Cygni and Epsilon (ε) Lyrae, nicknamed the Double Double since it’s actually a quadruple star. Both are easy to find with Albireo two fists to the right of Deneb and Epsilon just left and below of Vega.

New season, new sights. Clear skies!

7 Responses

  1. kevan hubbard

    Yes the full moon sends out a potent light.it always gets me seeing idiots jogging along with blazing LED head torches blinding the rest of us under a full moon.i even saw one running around a street lit town centre with a blazing LED head torch.

    1. astrobob

      Kevan,
      I’ve been tempted to feel the same way, but for the runner, it might also be a safety measure — easier to be seen.

      1. kevan hubbard

        I fear mainly a fad the one’s that I have seen have been on car free paths.ive was once walking back from a nearby village where I’d be stargazing down a disused railway line and about 50 of them came the other way on some kind of nocturnal charity walk I should guess?I don’t think my eyes ever recovered from that!

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