| Jun 01, 2006

Night Skies - June 2006

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Night Skies - June 2006

TheNightSkies of June, 2006:Mars & Saturn Pass Though a Beehive

by Leo Enright


The arrival of June in this part of the world always means that we can expect to have the longest days and shortest nights of the year. On the day that is called “the solstice” (which is derived from two Latin words meaning “the sun standing still”), namely June 21st, the sun appears at its northernmost location in the sky of any time during the entire year. If we regularly watch its rising in the morning, we can easily note that its current rising is well north of the eastern point on the horizon, and if we watch its setting, we can also see that it now sets a considerable distance north of the western point on the horizon. Skywatchers well know that those rising and setting points are at their northern extremities, and starting the next day, risings and settings will be slightly farther south along the horizon. Many people may also have noticed that, for a couple of hours each day in late May and in June, both in the early morning and late evening, rays of sunlight actually shine through the north-facing windows of our houses. Locally June’s sunrise times range from 5:24 a.m. EDT to 5:20 a.m., and sunset times from 8:46 p.m. to 8:57 p.m.. The dates of earliest sunrise and of latest sunset (a fact that is quite surprising to many people) are very dependent on the latitude where one lives and are NOT on the date of the solstice. At our latitude, the date of earliest sunrise is actually June 15th when it occurs a whole minute earlier (at 5:20 a.m.) than it does on June 21st (at 5:21 a.m.). Locally the date of latest sunset is June 27th, when the sunset time (8:57 p.m.) is a whole minute later than it is on June 21st (8:56 p.m.). Of course, the day-to-day change in the sunrise and sunset times in June is only seconds – certainly much less than it was in the month of March!

Like May, the month of June always brings very long twilights – those periods of time when the sun is below the horizon, but the sky, especially the western sky in the evenings and the eastern sky in the mornings, is not completely dark. Locally, evening twilight lasts until well after 11:00 p.m. throughout June, with the latest “end of twilight” being at about 11:28 p.m. in the week following the solstice. The first hint of morning twilight can be detected a few minutes before 3:00 a.m. during most of the month. In other words, at this latitude in June, there is a totally dark night sky for only about 3 hours each night.

During those long evening twilights we have a great opportunity to see, and identify, four of the five bright planets. Only one of the bright planets holds itself back for viewing in the morning twilight. The first planet to be seen in the evening twilight will be brilliant Jupiter in the southern sky. Careful observers, using only the naked eye, should be able to detect 2 things about Jupiter this month: over the course of the month it decreases slightly in brightness, and it appears to move very slowly westward (to the right) and away from the nearby star that is the brightest one in the constellation Libra (generally known by its Arabic name, Zubenelgenubi). If these observers have binoculars, they will also easily discover 2 more things: that Jupiter is encircled by 4 moons whose positions change every night, and that Zubenelgenubi is actually a ‘double star’. In the western sky, about an hour after sunset every clear night this month we have a great chance to see a classic “dance of the planets”, this time featuring reddish Mars and yellow-white Saturn. In the first week of June they are separated by almost the width of a fist held at arm’s length, with Saturn appearing up and to the left from Mars. Every day Mars moves a bit closer to Saturn, until on the evening of JUNE 17th they are EXTREMELY CLOSE TO EACH OTHER! Please, do not miss this rare planetary conjunction that evening! (Mars and Saturn have not appeared this close since 1978!) (Remember that it’s about 1 hour after sunset!!) For the rest of the month, watch these two planets continue to move apart until by month’s end they appear as far apart as they were on June 1st, but in the opposite direction from each other. Binocular viewers are in for a special treat as both Mars and Saturn, at mid-month, appear very close to large cluster of stars known to astronomers as M44 or the Beehive Cluster of stars. Though from a rural, unpolluted night sky, this beautiful cluster may be seen with the unaided eye, binoculars should be used to appreciate the number of stars it contains. On June 15th, Mars appears right in the centre of the cluster, but a binocular view any evening a week before or after that date will show “the double planetary march through the Beehive”. (Remember, of course, that the cluster of stars is actually many thousands of times further away than the two planets.) Mercury, the fourth planet of the evening sky, is down and to the right from both Mars and Saturn, and it may be seen during most of the month, but binoculars may help in finding it low in the western sky, particularly in the latter part of the month when it is not as bright as it was at the beginning of June. Brilliant Venus, the morning planet for this summer, is seen throughout the month rising about 3:20 a.m. and dominating the eastern sky until sunrise.

The moon presents some very interesting conjunctions with bright planets this month. A waxing gibbous moon glides past Jupiter in the evening sky on June 7th and 8th. On the morning of June 22nd, the slim crescent moon presents a gorgeous sight above the Pleiades Star Cluster and brilliant Venus; the following morning, the 23rd, it is just to the left of the cluster and the planet. Between June 26th and June 29th, there are 3 evenings when a slender waxing crescent glides past 3 planets in the western evening sky. Try not to miss the views as it appears to the right of Mercury about 45 minutes after sunset on the 26th, and to the right of Saturn at the same time on the 27th and just above Mars at the same time on the 28th. Actually, the following night, June 29th gives us a chance to see the lunar crescent beside a fourth bright object, this time a star, Regulus, the brightest star in the constellation Leo, the Lion.

Though the nights of June may be short, there is a great deal to see and enjoy besides the bright planets that can be seen even in twilight. As the Summer Triangle of bright stars rises in the east, and as the great arm of the Milky Way Galaxy sweeps overhead in the late evening, and as the Great Sagittarius Starcloud , containing the core of our home galaxy, takes it place in the southern sky, ENJOY these precious vistas! To assist you in this great exploratory journey, a recommended book, with its multiple star maps and numerous observing tips, is The Beginner’s Observing Guide, which is now available at Sharbot Lake Pharmacy.

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