Hobbies And Interests
Portability
One advantage to a star wheel is its portability. Often made of lightweight materials, such as cardboard, it is the size of standard letter paper or smaller, so it is no burden to carry. Star wheels can be easily tucked in a book bag or backpack. City dwellers who can not easily see the stars due to the lights, can take a trip out to the countryside for stargazing with a planisphere.
Customization
Star wheels can be customized to show more or less detail. Of the many planisphere designs, some have few details, while others shows thousands of stars on one side of the wheel. Some are designed to show only the brightest stars that are visible, even in cities. Print out a chosen style. This will avoid confusion for a beginner, or offer a vast array of constellations for the more advanced.
There are also varied pocket designs. The pocket is the layer that covers the wheel. The inside hole or window, where the wheel shows through, can be several different oval shapes. Certain shapes work better at certain latitudes. For example, a pocket for latitudes of 50 to 60 degrees north of the equator can be nearly a circle, while pockets for equatorial latitudes tend to be flatter on one side. Choosing a different pocket shape can change the chart your planisphere displays.
Interpretation
The main disadvantages of using a star wheel are primarily in the learning curve. The wheel is a small representation of a huge night sky, and shows all horizons in just a few inches. Stars that appear to be very close together on the wheel may be very far apart in the sky. Interpretation of the information takes some getting used to. It requires translating small eye movements to read the wheel into very large body movements to see the sky from horizon to horizon.
Time Differences
Another trick to reading the wheel is time differences. Time zones are very large. The sky at exactly 9 p.m. standard time will be slightly different on the eastern side than the western side of the time zone, because the Earth is still turning. This difference is the local mean time. The star wheel works on mean time, not standard time. If you are in the western part of your time zone, your star wheel may be showing the stars slightly ahead of you; if you are in the east, they could be slightly behind. Luckily, differences of a half hour or less between standard time and local mean time do not affect stargazing, so many people can still find the stars on their wheel.
Planispheres also do not include daylight saving time. This can throw off your stargazing unless you compensate for the discrepancy. If you are in daylight saving time, remember to subtract 1 hour from your time to find the correct time on your wheel.