June’s Evening Skies

June 2013  :  Dave Huestis

Though the month of June does provide much more reasonable temperatures for amateur astronomers to enjoy their hobby, most of us do not welcome the summer months. Why? The sky doesn’t get sufficiently dark for deep sky objects (galaxies and nebulae) until close to 10:00 pm as we near the summer solstice on June 21 at 1:04 am. And morning twilight begins between 3:30 and 4:00 am! These circumstances definitely limit a serious stargazer’s observing session.

Still, dedicated sky enthusiasts find time to scan the heavens no matter what time of the year it is. While many stargazers will be concentrating on observing beautiful Saturn (see last month’s column), this summer many other astronomical events will be observable with and without telescopes. Here are a few highlights that will be visible during June.

More than likely you will hear about another supermoon during June. Even though this term is not an astronomical one, back in 1979 an astrologer coined the phrase, and it has become more widely used in the media lately. The term is used to describe a time when a Full or New Moon coincides with the Moon’s closest approach to the Earth. The Moon’s elliptical orbit brings it as close as 221,824 miles and as far away as 252,581 miles. On June 23 at 7:32 am EDT the Moon will be full, just 32 minutes after reaching perigee (close approach). At that time the Moon will be approximately 221,853 miles from the Earth.

While this scenario will make the Full Moon the closest one until August 10, 2014, it is not the closest it can be, and I seriously doubt whether anyone could truthfully say that it looks any larger than any other recent Full Moon or even any brighter than usual. While it is true that a Moon at the extreme perigee (farthest distance from Earth) appears about 14% larger and 30% brighter than the extreme apogee, making an observation from one Full Moon to the next would not be as noticeable. However, imaging successive full moons using the same camera and lens would definitely allow for an accurate comparison.

Also, so-called supermoons are not at all as rare as they are made out to be. There are four to six such events yearly. So while a rising Full Moon may appear larger than normal when foreground objects allow a comparison, June’s full strawberry moon would hardly receive any attention if not for the hype. At least it may have folks looking at the sky and marveling at our desolate neighbor.

During the last week of May through the first week of June, stargazers will be able to observe three planets above the western horizon after sunset. While this column is primarily prepared for June, it often is published before the new month begins. Start observing this triple planetary conjunction on May 24. You will see brilliant Venus, bright Jupiter and much dimmer Mercury above and to the left of the sunset horizon point. You will need an unobstructed horizon in order to view this conjunction of planets. Once evening twilight has deepened, all three heavenly bodies will be within twelve degrees or less (about a fist held at arm’s length provides this measurement) of the horizon. (See the May issue of The Skyscraper, the monthly newsletter of Skyscrapers, for diagrams showing sky charts for May 24-31 at www.theskyscrapers.org.)

Watch the positions of theses planets change with each successive night. On the night of May 28 Jupiter and Venus will be only one degree (two Full Moon diameters) apart. On June 1 the planetary trio will form a straight line from and above the sunset point on the horizon in order of Jupiter, Venus and Mercury. (This scene will look practically identical to the sky diagram for May 31 in The Skyscraper newsletter.) It will be quite a beautiful sight to behold. Jupiter will soon be lost in the solar glare, so bid farewell until later this year. On June 10, Mercury and Venus will be joined by a thin waxing crescent Moon passing nearby. This sky scene would make an excellent opportunity to snap a few images.

Mercury will reach its highest elevation from the horizon on June 12 and will then begin to sink lower each night. Meanwhile, Venus will continue to rise up past Mercury as the month progresses. On the 18th they will be a mere two degrees apart (that’s four Full Moon diameters). Venus keeps on its upward swing into a darker sky, while Mercury will quickly draw closer towards the Sun and will soon be lost in the solar glare.

I must add a word of caution here to beginner stargazers. Do not attempt to locate these planets when the Sun is still in the sky. While it would be futile to try anyway, you don’t want to risk losing your eyesight should you wander too close to the Sun, either with your eyes, binoculars or a telescope. Many more astronomical wonders await your gaze throughout the coming year.

In conclusion, while the initial June conjunction of planets just above the western horizon will be difficult or impossible to observe from the local observatories, Saturn will still be the focus of attention throughout the summer. Afterwards the summer constellations along with the Milky Way will provide access to a multitude of clusters and nebulae at which to marvel. While it won’t get dark enough to recognize adequately many of the familiar star patterns until after 9:45 pm or so, the sky vault will certainly reward a patient stargazer with splendid views of the heavens once twilight has faded.

Don’t forget that the local observatories provide open nights for telescopic viewing of the heavens throughout the summer. Seagrave Memorial Observatory in North Scituate is open every clear Saturday night for observing. Ladd Observatory in Providence will be closed during the month of June for annual maintenance. Frosty Drew Observatory in Charlestown is open on every clear Friday night. Please visit the respective websites for details about opening times and closures.

Turn off the lights and turn on to astronomy. Good observing.