Opinion

Astronomical events almost over

Thursday, April 5, 2012

All the celestial excitement is about over for a while. What with all the planetary and lunar conjunctions it has been quite busy.

There are a few scattered celestial events left for April, but it will be mostly quite until the partial solar eclipse (yes, we will see it from Southwest Nebraska) on May 20, and an even bigger event on the fifth of June when an extremely rare event will occur. Venus will cross -- transit -- the face of the sun.

Venus crossed in front of the solar disc eight years ago, and after this transit, won't do it again for another 150 or so odd years. So, if you want to see it, don't miss it now, you will never see it again.

We are all familiar with an eclipse. A lunar eclipse happens when the shadow of Earth crosses that face of the moon blotting out any sunlight.

A solar eclipse happens when the moon moved between Earth and the sun blocking out any sunlight.

Neither of them are especially rare events, but they are especially fun to watch.

The partial solar eclipse is on Sunday, May 20. It will start at about 6:26 p.m. MDT and continue until sunset at about 8 p.m. MDT. Maximum eclipse for Southwest Nebraska will be at about 6:26 p.m. MDT when about 90 percent of the sun will be blocked out.

The path of totality will start in Texas and travel through New Mexico, Utah, Nevada, California, across the Pacific to Japan and extreme eastern China.

Even on the path of totality, the eclipse will not be total. It is what is called an "annular" eclipse where a small ring, or annulus, of sunlight ls left showing around the edges of the moon.

This happens when the moon is too far from Earth to completely block out all of the sunlight.

A planetary transit, however, is a much more exciting event. Such an event is only possible when the two innermost planets--Venus and Mercury -- pass between Earth and the Sun thus allowing their discs to be seen against the background of the Sun.

Transits of Mercury happen 13 or 14 times each century, while transits of Venus happen in cycles of eight years, 122 years, and 105 years. The last transit of Venus was in 2004.

For those of us in Southwest Nebraska, we will only see part of the transit, because the sun will set while the transit is still in progress. I am sure there will be places on the internet that will be showing all the transit from robotic telescopes.

SKY WATCH: Full moon, Friday, April 6. The moon will be near Saturn and Spica. Best observing time will be after 10pm MDT. The full moon will pay a visit to Saturn and the star Spica on Friday, April 6. Spica is the bright star just left of the moon and Saturn is the bright dot further left. On Tuesday, April 10, there will be a Messier Marathon presented by a robotic telescope in Italy. It will start at 6 p.m. GMT, which is about noon CDT. The marathon was clouded out on Sunday, April 2. Point your favorite browser to http://virtualtelescope.bellatrixobservatory.org/webtv.html

NEXT WEEK: More astronomical blathering.

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