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The Sky This Month - June 2012

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Written by Gary Boyle on
Post Date: 
Fri, 2012/06/01

The Great 2012 Venus Transit

Well that magical moment is almost upon us. The anticipation of witnessing the planet Venus crossing the face of the Sun has been the buzz in the astronomical community for the past few months. It was eight short years ago on the morning of June 8, 2004 that the Sun rose in the north east, sporting a huge black spot. From Ottawa, the transit was past the halfway point with Venus ready to exit an hour later. The view was spectacular and I was fortunate to witness such a rare event – a day I will never forget.

And here we are with yet another chance to behold the colossal passage in our lifetime. June 5, 2012 will your last chance and for some, the only chance to glimpse, photograph and savour the last transit of Venus for a long, long time. The next time the Sun, Venus and Earth perfectly lined up will be on December 11, 2117 and then December 8, 2125. That is the nature of transits as they line up in pairs, first a long gap of more than a century and then eight years afterwards. With the availability of personal solar telescope PST and high end filters, the images should be nothing short of spectacular.

The entire transit will take six hours and forty minutes to complete with all of Canada following the slow dance across the Sun until sunset except for a small portion of northern BC and Alaska that sees the whole show. Australia, Asia and Russia also have a ring side seat for the event.  

But when dealing with the sun, great joy comes with great danger. NEVER

LOOK DIRECTLY AT THE SUN. Under no circumstances should anyone try to glimpse the brilliant sun, no matter how brief or how low the sun is above the horizon without proper filtration. Many telescope stores as well as online retailers sell safe filters such as Baader film and filters. Any filter should be placed at the front of the telescope thus reducing glare by 99%. Never try homemade filters as smoked glass, unexposed film etc. Do not take chances with your eyes. It was unfortunate for even Galileo Galilee went blind looking at unfiltered sunspots.

If you are setting up a neighbour observing session with a filtered scope, be sure to cover the finder scope or you will melt the internal crosshairs or better yet, remove it. Remember it is safety first so never leave a scope unattended. Children are inquisitive and could damage the filter or heaven forbid take it off and look into the eyepiece. The Sun is a beautiful thing to enjoy and study as long as strict rules of keeping it safe is adhered to. Take a few minutes to review some other reading material from the RASC transit page. Here is hoping for clear skies in your area and enjoy this extremely rare event. Don’t forget to hook up the camera and take a few pictures. If the transit is clouded out, check the NASA web site for a live web cast. Mercury also transits the Sun but appears a lot smaller. Mercury’s next transit is slated for May 9, 2016.

We now switch from our daytime star to the traditional night sky. As the months come and go, so do the familiar seasonal constellations. Orion and his wintry friends are now immersed in solar glare; the distinctive swarm of galaxies belonging to Coma Berenices, Virgo and Leo are past the meridian and sinking lower westward as the weeks roll by. We now look to the east as the majestic Milky Way Galaxy is climbing up the sky. The venue of observable objects now switches from a majority of distant galaxies to primarily neighbouring globular clusters.

We start the tour of faint fuzzies with a loose globular cluster down in Libra. NGC 5897 is located close to 41,000 light years from us and 24,000 light years from the galactic center. By nature, globular clusters are perched around the nucleus of galaxies like shad flies around a street light. NGC 5897 measures a little less than half the size of the full moon. With an apparent magnitude of 8.5, you will need at least binoculars to catch it. Before leaving NGC 5897, move eight degrees to the 2 o’clock position to the bright third magnitude star named Zubenelgenubi. Together with the fifth magnitude F class star located a mere four arc minutes to the upper right, the two are thought to be physically attracted. The pair lay 77 light years from Earth and separated by only 5,500 astronomical units or 185 times the distance from the Sun to the planet Uranus. From the companion star, the brighter A-class Zubenelgenubi would appear as bright as our full moon.

From NGC 5897 move up to Zubeneschamali sitting at a distance of 160 light years from us and continue moving up in the same direction and distance till you get to M5. This is one of the nicest globulars you will see with a telescope. At 24,000 light years away and 165 light years wide, astronomers believe it is the oldest of its kind, about 13 billion years old. This magnitude 5.8 cluster is home to 105 variable stars. However the finest globular cluster in northern skies is M13 in the constellation Hercules. Roughly the same distance, brightness and size as M5, this target has more stars with estimates up to a million suns. Be sure to check out NGC 6207 which as an 11.6 magnitude elongated galaxy located 27 arc minutes east of M13. NGC 6207 is listed as 39 million light years away. Now here is a bit of a challenge. Nestled between M13 and NGC 6207 is an extremely remote galaxy known as IC4617. This magnitude 15.5 smudge is estimated to be close to 500 million light years away.   

It was only a few short months ago that we had our pick of four planets to observe, that number is now reduced to two. With Venus and Jupiter out of the picture, the planet Mars is still moving eastward through Leo and crosses over into the constellation Virgo on the 20th. By month’s end the red planet will set by midnight. Saturn never disappoints any view through the telescope. Its majestic ring and tiny moons are a joy any time of night.  

As a result of the Sun, Earth and Moon geometric lineup from last month’s annual eclipse, the June 4th full Honey will undergo a partial lunar eclipse. Just like the Venus transit mentioned above, the further west you travel the longer the duration of seeing the celestial show. The entire eclipse will occur over the Pacific Ocean. This month’s new moon is slated for June 19.

This year’s Summer Solstice occurs on June 20th at 23:09 UT. The Sun will be at its highest point on the ecliptic. If you were living in the Southern hemisphere, this would be your Winter Solstice. For us in the north, the days begin to shorten after this date.

Until next month, clear skies everyone.

Gary Boyle

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