This page copyright 2012 Steve Ford http://geeky-boy.com and is licensed under a Creative Commons Attribution 3.0 Unported License.
The first thing you want to do is find the ecliptic. The ecliptic is an imaginary line across the sky that the Sun follows as it rises and sets. Assuming you're in the Northern hemisphere the ecliptic will start in the East, rise in the sky at an angle toward the South, and finish in the West (just like the Sun). (If you're South of the equator you'll have to translate these instructions yourself. Sorry.)
Just as the Sun follows the ecliptic, so do the planets (approximately), so it's important to be able to imagine it drawn across the sky. To make matters worse, it moves between winter and summer. The best way to visualize the ecliptic is to use a planisphere.
Assuming you have a pretty good idea where the ecliptic is, you now need to figure out which planets will be up in the evening. Fortunately, the major planets (Venus, Jupiter, Saturn) will be the brightest stars in their area of the sky, so once you look in the approximate right place, you're sure to find it. Unfortunately, due to the way that planets orbit the Sun, we can't predict where the planets are based only on the month of the year. Instead, we must check with a sky map. Some newspapers tell you which planets are up, but without a sky map, it can be hard to follow their instructions to find them.
The best skymapping web site that I've seen is http://www.fourmilab.ch/yoursky/ (there's also a windows version of the same program that will give you faster response time than the web). The horizon views are generally easier to use than the full-sky map. One nice thing about this site is that it gives you the map for the exact time and date that you bring it up! Go there right before you go outside and you will see exactly where the planets are.
Another fairly good one is http://www.dustbunny.com/afk/sky/mappmzc.htm. For planet viewing, you typically want the South view, especially in the winter.
Yet another is http://www.firstnet.co.uk/users/ray/skymp.html with a monthly sky map (although the page loads slow in the US).
Skypub has a set of detailed maps. Go to http://www.skypub.com/whatsup/whatsup.shtml and click on the desired "...Sky Highlights" link. For example: February 1998 Sky Highlights. Click on the small star map at the top and you'll get a big detailed map.
Alternatively, get a subscription to "Sky Calendar" from Abram's Planetarium. It only costs about $9.00 US per year and includes some good tips about all kinds of things to look at. For information and subscription, go to their web page.
One problem with trying to use a monthly sky map to find the planets is that the planets do move during the month. For example, it's now January 1998 (as I write this). Early in the month, Jupiter is visible. By the end of the month it won't be.
The ultimate solution to this problem is to get a sky mapping program for your computer. This will give you an up-to-the-minute map of the sky, including planet locations. Both beginners and experienced amateurs alike can get a lot of benefit from good sky mapping software.
There are lots and lots of these programs available, but I'm going
to recommend "SkyMap" (creative name, eh?). It is shareware, which means
that you can download it for free and use it for a certain period of time.
See my SkyMap review for more information.
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then check it out now.