COMING SOON: The 2017 summer season is quickly approaching. With that, warmer evenings and more people wanting to be outdoors should bring more attention to the wonderful night sky, even though nights are not as long. An upcoming edition of this column, however, will be featuring a special daytime highlight like no other in the sky, a total solar eclipse. Always a rare event, this one is rarer still, with the Moon briefly blocking out the Sun along a narrow path right across the continental United States. The date is Monday, August 21st. More to come!
NEXT CLEAR NIGHT: To get the best view of the stars, it’s best to be away from city lights. Interestingly, one of the finest sights in the night sky is a stellar city, a way to describe globular clusters. These are massive balls of many thousands of stars, not touching but packed in close proximity to one another, combining their individual starlight to form a spectacular, shining sphere, frayed around its circumference.
It’s too bad that we don’t have any so close to us in the galaxy that it is immediately obvious to anyone looking up with eyes alone. Many of them are visible in a small telescope, and a few are close enough to show vividly in the eyepiece. A handful (no mortal hand) can be seen with binoculars as “fuzzy spots”, and in a very dark sky, showing like a dim star to unaided eyes.
Here’s one you can see the next clear night, with a pair of binoculars.
One of the best is listed as M13 on Charles Messier’s famous list of deep sky objects, compiled in his native France in the late 1700’s. Astronomer Edmond Halley is credited for discovering M13, in 1714.
M13 is easily found on springtime evenings, in the constellation Hercules, the Strong Man.
They are not so obvious to the unaided eye simply because of their placement around the Milky Way Galaxy. Our Sun and its planets are right within one of the Milky Way’s spiraling arms of stars and dust, orbiting the galaxy’s big, bright central bulge. The spiral arms stretch around in the same “plane”, level to one another. Globular clusters orbit the galaxy from very high “above” and “below” the plane.
Picture a porch lightbulb fastened in the middle of a phonograph record; the record is the “plane”. The moths swirling around the bulb can be likened (this is a stretch) to the globular clusters.
M13 has as many as 300,000 stars jammed closed together. A six inch telescope will begin to resolve the globe into individual stars. Smaller telescopes show it as a bright, fuzzy ball. The impression of a vast city of stars increases with even larger backyard telescopes.
The globe is so big, it takes light 145 years to pass from one side to the next. M13 is approximately 25,100 light years from the Earth. Remember, the nearest star to the Sun is just over four light years away. Each light year is about 5.8 TRILLION miles.
In 1974, the Arecibo radio observatory in Puerto Rico beamed an encoded message about the human race, targeted to reach the center of M13, in hopes of reaching some alien civilization. Of course that will take over 25,000 years to get there. Never mind waiting for a reply!
Star charts found in astronomy books at your local library, as well as in Sky & Telescope and Astronomy magazine (also see their web sites), will point out Hercules and where to spot M13.
First quarter Moon is on June 1st. Be sure to see the brilliant planet Jupiter high in the south in early evening!
Keep looking up!
— Peter Becker is Managing Editor at The News Eagle in Hawley, PA. Notes are welcome at email@example.com. Please mention in what newspaper or web site you read this column.