Celestial gems fill the sky this week
Now that it gets darker a lot sooner in the evening, it's easier to stargaze before the sandman starts working on your eyelids. You can spend a lot more time with your telescope or even just a nice pair of binoculars.
There are loads of celestial treasures among the constellations in the late Butler summer sky. Most star clusters, nebulae, double stars, and even whole other galaxies outside our Milky Way aren't available to the naked eye, but you can dig them out with a bit of patience and optical aid.
Three of the heavens' nicest jewels right now are nearly overhead at the end of evening twilight, around 8:30 p.m. The easiest one to see is the star Albireo, the second brightest star in the constellation Cygnus the Swan, otherwise known as the Northern Cross.
The best way to find it is to face directly south and look directly overhead. The brightest star you see is Vega, the brightest star in the constellation Lyra the Harp. Vega is also the third brightest nighttime star we see in our skies.
Anyway, make a fist and extend your clenched fist at arm's length. About two fists at arm's length to the lower left of Vega, look for the Northern Cross. The moderately bright star at the foot of the diagonally orientated cross is Albireo.
To the naked eye, Albireo looks like any other star in the sky, but with even a pair of binoculars, you can see that not only is Albireo a double star, but a colorful pair.
One star has a golden hue and the other is distinctly blue. I guarantee you'll love what you see!
The double stars of Albireo are about 430 light-years away, with just one light-year equaling nearly six trillion miles!
Astronomers don't know for sure, but there's a good chance that the two stars of Albireo may be gravitationally bound to each other, making them a binary star system. The two stars are separated by around 40 to 60 light-years. If they are a binary star system, they would orbit each other once every a hundred thousand years or so. Don't wait for that or you will fall asleep for sure!
By the way, in the mid '70s it was discovered that the golden star of Albireo is itself a binary star, but there's no way you could split the components unless you had one heck of a telescope!
The second celestial gem up in the high south sky is Messier object 13, better known as the Great Hercules Cluster, one of the sky's true wonders, residing in the faint constellation Hercules the Hero. The best way to find that is to face south once again and find the bright star Vega. Look for a trapezoid of four faint stars you should be able to see with the naked eye, unless you really have a lot of light pollution. That trapezoid is pretty much the center of the Hercules constellation.
About a third of the way from the upper right to the trapezoid's lower right side, you'll find the Hercules cluster. You won't see it with the naked eye but with a good pair of binoculars or even better, a telescope, you'll see what at first looks like a spherical fuzzball.
If you have powerful enough optics, especially if you can view it from darker countryside skies, you'll see that it's a cluster of many, many stars, known as a globular cluster. This is the best cluster in the skies. Astronomers figure it's about 25,000 light-years away or about 145,000 trillion miles. Up to a million stars may be crammed in an area a little over 800 trillion miles wide. Through even a moderate telescope you can see some individual stars at the edge.
As it is with all telescopic objects, look at the cluster for extended periods through the eyepiece of your scope to let your eyes get used to the darkness of the eyepiece field. I absolutely love showing off the great Hercules cluster with giant telescopes at my star party programs.
The last celestial treasure to search for is also the most elusive: Messier object 57, the Ring Nebula. It's another planetary nebula that really looks like a ring. It shows a slightly bluish tint that reminds me of a little cosmic smoke ring.
The Ring Nebula lays in the constellation Lyra the Harp, between two of the four stars that make a small parallelogram allegedly outlining the little celestial harp. Just keep scanning between the two stars that make up the parallelogram's bottom end, opposite the bright star Vega.
At first, the Ring Nebula looks like a faint little grayish star, but if your scope is powerful enough you may be able to resolve the ring. Finding the Ring Nebula does require some patience to locate, but it's definitely worth the effort.
Planetary nebulas are stars like our sun that blow off the last of atmospheric gases as they shrink down to a white dwarf star about the size of our Earth. This will happen to our sun in about six to seven billion years. That's when our sun officially retires!
Upcoming Celestial Happenings: The waxing gibbous moon, on its way to becoming full, will be passing below the bright planets Jupiter and Saturn in the low southeast sky in the early evening. The two planets are the brightest star-like objects in that part of the sky. On Thursday evening, the moon will be just to the lower right of Saturn and on Friday, look for the ovalish moon to the lower right of Jupiter.
Don't miss the show this coming week
Mike Lynch is an amateur astronomer and retired broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is the author of “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications and available at bookstores and adventurepublications.net. Contact him at mikewlynch@comcast.net.
