Saturday, July 21, 2012

Low Tech: Planisphere

In the above composite, the image on the left is a 16th-century astrolabe and the image on the right is a contemporary planisphere. Image Credit: Wikipedia contributor "Maksim" (astrolabe); Wikipedia contributor "Wammes Waggel" (planisphere).

Before smartphone apps, before the Internet, even before personal computers, amateur astronomers who were on a budget could still obtain, at little or no cost, the tools they needed to pursue their hobby. The trade-off was that they had to make the tools themselves. Here is one such nifty tool. It's called a planisphere.

A planisphere, or star wheel, is one of the most useful amateur astronomer tools. A planisphere can help you learn how to recognize stars and constellations. A predecessor to the planisphere is the astrolabe, an instrument invented in ancient Greece around 150 BC, and some say invented by the Greek astronomer, geographer, and mathematician Hipparchus.

A planisphere is very easy to learn and use. As long as you can spin the wheel to the correct local time (this does require knowing what time it is), you have at your finger tips a star chart of the nighttime sky over your head. And to take this low-tech theme one step further, why buy when you can make? And even make for free?

Of course, I understand there are still those who object. You are saying, "Why make your own planisphere? Well, for one reason, customization. Being able to make custom planispheres may help you easily focus on your astronomical subject of study. And choosing your own colors can optimize visibility, change lines, borders or even constellation art. Another reason to make your own is the self confidence you will feel when you construct something that everyone else has said you must buy before you can have. Finally, it can give you a great sense of nostalgia to remember, and to show others, what it was like before there were star chart apps...

There are several places online that provide, for free, all you need to download and create your own planisphere in no time. Here are just a few:

Make a Star Wheel! Sky and Telescope.

Planisphere. National Research Council, Canada.

Create Your Own Planisphere with Uncle Al's Sky Wheels. Ventura County Astronomical Society.

Star Wheel. Astronomy in your hands.


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