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Winter = Cold Weather = Good Seeing
Observing >
So you got a new telescope for Christmas, eh? Well, even if you didn't, winter is a perfect time to get the old light bucket out, dust it off, and take it for a spin. There are some heavenly wonders out there waiting to be wondered at.
One reason it is such a good time to observe is that it gets dark so early, giving one more time to absorb it all. And, believe it or not, cold, clear nights can allow better "seeing." That's fancy astrospeak for "there isn't as much turbulence in the atmosphere making it feel as if we're looking at the stars and planets from the bottom of a pool."
Starting off easy let's first take a look at the Moon. Unfortunately, it is essentially full at the moment. Despite the fact that it seems like a Full Moon would be the best moon to spy on, it is not. It appears through a telescope as a flat, dingy disk. And the fuller moon has this annoying tendency to brighten the sky --- bad news for astronomers.
The quarter Moons --- the week before and after Full Moon --- are the best for using your scope to see the striking details of the surface craters and valleys and the long shadows streaking across the lunar surface.
Just
after sunset, look to the southwestern skies for that big bright "star"
following the sun only about 20 degrees above horizon. Through your scope
you'll be looking at the mostly illuminated bright disk of our nearest
neighbor, Venus. Its brightness and gibbous lighting make it look like
a very small version of our Moon.
But you'll also see firsthand why observing objects down near the horizon can be so frustrating. There is a lot more of our interfering atmosphere for Venus' light to go through and the day's heat is still rising off the land. Thus it is not the clearest, steadiest image you can get.
You can see the differences in bad and good "seeing" when you next take a look at Saturn, the jewel in the January skies. Finding it is easy. If you know where Orion is follow a line from his bright blue star, Rigel, through the Belt, then through the big orangey star Betelgeuse, right to Saturn.
Bright
and golden, Saturn shines right between the twins of Gemini, very near
the Moon now. If this is the first time you have used a scope you will
be more than pleasantly surprised when you first spot The Lord of the
Rings. An annual favorite at star parties, the rings have an aesthetic
jaw-dropping beauty all their own.
See for yourself, if you have the time and a clear night, the difference that altitude makes in the image you see. When Saturn is near the eastern horizon after sunset, rising with Orion, the heat rising from our surface will cause the notorious underwater look --- bad seeing. When Saturn reaches near overhead around midnight, the disk and rings should be tack sharp --- good seeing --- and worth staying up for.
If you can stay up into late night, you'll see the return
of the king, Jupiter, as it makes its almost-ready-for-primetime comeback
after being gone since early last summer. It is the very bright "star"
in the eastern sky.
Even with binoculars you can easily spot four of Jupiter's moons --- the
Galilean satellites, Io, Europa, Ganymede, and Callisto --- spotted first
by master Galileo himself 400 years ago.
With
a scope, though, you can see the bands of cloud patterns belting the planet,
a reminder of Jupiter's terrifying atmospheric conditions. A very good
telescope may spot the Great Red Spot, a storm raging for centuries now.
How great is it? Several Earths could fit into it with plenty of legroom.
As the Moon begins to wan in the next couple weeks, you can begin to pick out the less conspicuous --- but still beautiful --- celestial wonders, including the Orion Nebula, the Pleiades, globular clusters, and other galaxies.
And after that there is the beautiful spring sky and then the summer spectacles and then ...
Mark Ritter teaches astronomy at Temecula Valley High School and can be reached at mritter@firstlightastro.com.
Posted by Administrator at 2004.01. 3 12:52 PM | Comments (0)
