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Wednesday, May 4, 2016

Watch out for the zodiacal light

Thursday, March 24, 2011

Oh Boy!! Where to start? For the next couple of weeks check the western horizon an hour after sunset for the zodiacal light, sunlight reflected off the zillions of dust particles scattered along the galactic plane.

This reflected sunlight will look similar to the Milky Way and will extend up from the horizon to almost overhead forming a triangle along the ecliptic, the path the sun and planets follow through the sky.

A very dark place will be needed. Nautical twilight starts at about 8pm MDT and astronomical twilight at about 8:30 p.m. MDT.

When the light occurs before sunrise it is called a "false dawn" because it gives the appearance that sunrise is coming soon.

Our old friend Orion has passed the southern meridian into the southwest portion of the sky and his belt is almost level with the horizon.

That is one way the ancients knew the spring season was upon them. In fact, spring (the vernal equinox) was last Sunday, March 20.

With the arrival of spring another of our old friends, Leo, the Lion, is "leaping" up over the eastern horizon after sunset these evenings. Also with Leo comes another binocular challenge.

At about 8:30 p.m. MDT, find Leo above the eastern horizon. The backwards question mark for the head and mane and the three stars making a triangle for his hindquarters.

Imagine a line running between them for his belly. About halfway along that line and a little below use your binoculars to find three very nice magnitude 11 galaxies. They will all be within the binocular field of view

They are, from the left, M105, M95, and M96. Items on Mr. Messier's list of things that are not comets.

For a further challenge slide back toward the hindquarters triangle. Where the triangle joins the line go down just a little for two more very nice galaxies, M65 and M66. Both are about magnitude 10 and both about 35,000 light-years away.

Wow, imagine what the sky would look like if you were living on a planet in one of those galaxies.

Speaking of Messier objects, now is the time of year when a particular bit of organized astronomical insanity sets in, sort of an astronomers version of "March Madness."

Forget the basketball games and the charts of teams, there are other charts to organize.

From mid-March into April is the season of the Messier Marathon. This is where astronomers try to locate all 110 Messier objects in one night. Yep, one night.

Starting in the west just after sunset, across the sky into the east just before dawn. The location of the object has to be plotted, found, and observed all in one night. See what I mean by insanity. Who needs basketball games?

SKY WATCH:

Third quarter moon Saturday, March 26. Mercury is as high in the western sky after sunset as it is going to get. There are still opportunities to view the speedy little planet for a few more days. It will rapidly plunge toward the horizon only to re-appear as a morning object in early April. Jupiter is very low in the glow of the setting sun and may not be viewable. Jupiter will return in May. In the morning sky Venus still holds sway as queen of the morning. On Sunday morning about a half-hour before sunrise start looking for Neptune to join Venus. The pair will draw closer to each other being closest on March 26 and 27. They will be joined by a slender crescent Moon on March 30 and April 1.

NEXT WEEK:

More astronomical blathering.


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Vernon Whetstone
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