As we approach the Summer Solstice in the northern hemisphere, this year on June 21 at 11:54 a.m. EDT (Eastern Daylight Time), here in Rhode Island many folks revel in the extra daylight hours, especially in the evening. Astronomers are not among those individuals because our skies do not get fully dark until about 10 p.m., and dawn’s early light starts around 4 a.m. That leaves little time to explore the universe with telescopes and cameras to capture the beauty of the heavens. Then as the summer months continue, we must contend with high humidity and pesky mosquitoes.
However, there are a couple of planets we will welcome back to the evening sky over the course of this summer. They are Jupiter and Saturn. These distant worlds reveal much detail in the telescopes at the local observatories.
Jupiter and Saturn
Jupiter will reach opposition on June 10. That means it will rise as the Sun sets. That is also the date of its closest approach to the Earth for this year. Unfortunately, the late rise time on June 10 means some of the local observatories may not be able to focus on Jupiter due to their respective horizon views. Also, because Jupiter will rise in the southeast and travel along a shallow arc across the sky, it will take some time to clear the often murky atmospheric conditions low to the horizon.
I do not wish to discourage one from observing Jupiter if you can. Even as this column goes to press during early June you could wait until Jupiter rises much higher into the sky to begin observing it. My associates have been observing Jupiter in the early morning sky for months (when the weather cooperated). I will provide a Jupiter observing guide in my July column.
Two hours after Jupiter rises, our solar system’s beautiful ringed world, Saturn, will rise. Saturn too will take a similar arced path into the sky, so it also will not rise very quickly above the horizon. You should wait a few hours before observing Saturn and his magnificent rings. Saturn reaches opposition one month later on July 9. My observing guide to Saturn will also be included in my July column.
Mercury and Mars
Within 20 minutes or so after sunset (8:24 p.m. EDT) on the evening of June 23 you can catch a glimpse of our solar system’s innermost planet, Mercury. Look about 10 degrees (a fist held at arm’s length provides this measurement) above the west-northwest horizon. You’ll require an unobstructed view to succeed in this observing challenge. Furthermore, an even more challenging task will be to locate the red and dimmer planet Mars 2.5 degrees below and to the right of Mercury. The gauntlet has been dropped. Who will accept and succeed in this challenge?
One of the jewels of the summer sky resides in the constellation of Hercules. I’m referring to the showpiece of northern hemisphere globular clusters, M13, so designated for being the 13th entry in the sky catalog of 18th century astronomer Charles Messier. This object contains hundreds of thousands of stars. Once you know where to look, M13 can still be detected with the naked-eye as a fuzzy patch from dark-sky locations in Rhode Island.
You can locate Hercules on June 1 about halfway up in the eastern sky around 9:30 p.m. Find the bright star Vega in the constellation of Lyra and Hercules will be the neighboring constellation to its upper right. Four main stars called the keystone outline the body of Hercules, while two streams of stars form his arms and another stream comprise his legs. Though his extremities look like a stick figure, Hercules has been bulking up on his body. While the constellation has a rich mythological history, space does not permit me to relate it here. Just suffice it to say that the star pattern represents the mighty Hercules of “12 labors” fame kneeling upon the head of Draco the Dragon, holding a club in one hand, and a branch in the other.
To locate the globular cluster please reference the accompanying star map. M13 lies between the two stars that form the western side of the keystone. It is about one-third of the way from the northern most star of the keystone. If you can’t detect it with your naked eye, try using a pair of binoculars. It looks like a small tail-less comet.
Once you’ve found M13, use a telescope if you have one. A small refractor will show it as a small diffuse patch of light, much like the nucleus of a comet. Larger scopes, say a four- or six-inch reflector, will begin to resolve individual stars within this beautiful beehive of stars. And the beehive description is quite apt, for if one could speed up time you would see these stars, which are all gravitationally bound to the cluster and number about 300,000, orbit the cluster like bees around a hive.
One of my favorite turn of the 20th century authors is Garrett P. Serviss. I often quote him in my columns because he had such a descriptive and poetic style of writing. For your enjoyment I have excerpted a quote concerning M13 from his wonderful book, “Pleasures of the Telescope.”
“...smaller instruments reveal only the in-running streams and the sprinkling of stellar points over the main aggregation, which cause it to sparkle like a cloud of diamond dust transfused with sunbeams.” “It is a ball of suns. Now you need a telescope. You must have one. You must either buy or borrow it, or you must pay a visit to an observatory, for this is a thing that no intelligent human being in these days can afford not to see. Can it be possible that any man can know that fifteen thousand suns are to be seen, burning in a compact globular cluster, and not long to regard them with his own eyes?”
On the next clear and moonless night, go out and locate the great Hercules in the sky. Binoculars will certainly show you M13, but a telescope will reveal all its splendor. Telescopic views through the larger telescopes at the local observatories are quite impressive. Think about the above description while you enjoy the image.
Take advantage of the viewing opportunities provided by the local observatories as the summer months progress. Jupiter and Saturn will be the primary focus of attention from mid-summer onwards into fall. In addition will be various phases of the Moon, as well as looks up and down the expanse of our own Milky Way galaxy. Remember, summer brings late sunsets, so please check the respective observatory websites for their open dates and times before venturing out for a visit. Seagrave Memorial Observatory (http://www.theskyscrapers.org) in North Scituate is open every clear Saturday night. Ladd Observatory (http://www.brown.edu/Departments/Physics/Ladd/) in Providence is open every Tuesday night. The Margaret M. Jacoby Observatory at the CCRI Knight Campus in Warwick (http://www.ccri.edu/physics/observatory.htm) is open every clear Thursday night. Frosty Drew Observatory (http://www.frostydrew.org/) in Charlestown is open every clear Friday night.
Keep your eyes to the skies.