The Use of a Star Finder : The Use of a Star Finder A planisphere, sometimes called a Star Finder is very useful
It can be used to “set” the sky for a particular time and date
This allows the correct position of the constellations to be seen
With the Star Finder is set it is possible to find constellations of interest
Because star positions change very little over a human lifetime a planisphere is useful for many years
How is it made : How is it made There is a Sky Disk in a Frame, this one is blue
There is an oval area in the Frame through which a portion of the Sky Disk is seen
The edge of the oval represents the horizon
Toward the North part of the oval is a brass hole
This hole is a small axle which represents Polaris the North Star around which the Sky Disk rotates ….. as does the real sky
A Typical Star Finder : A Typical Star Finder Here is a typical Star Finder
The planisphere’s sky : The planisphere’s sky The brass axle
The planisphere’s sky : The planisphere’s sky The planisphere’s sky with the month names on the inner movable dark blue Sky Disk.
Set the date and time : Set the date and time To view the sky on 21 September for any year at 8:00 P.M. set the Sky Disk to match the time
The time is found on the Frame and the date is found on the Sky Disk
The sky is now set : The sky is now set Notice the Big Dipper
It seems to be upside down
To Use the Star Finder : To Use the Star Finder Since you can see from the Star Finder that the Big Dipper is located in the Northern Sky
You must orient yourself to face North
Then you must orient your Star Finder to point to the North
Hold the Finder Correctly : Hold the Finder Correctly Notice that the North part of the Finder is oriented down pointing to the Northern horizon
It is actually right side up as far as the sky is concerned.
Remember a road map is held down because roads are on the ground
But a Star Map is held up because the stars are up in the sky
You can see the Dipper : You can see the Dipper The Big Dipper is now seen as it appears in the Northern sky at 8:00 P.M. on 20 September
Notice that the
Dipper points
to Polaris the
North Star
represented by
the brass axle
An example: find the Big Dipper : An example: find the Big Dipper Follow these steps to find the Big Dipper Orient the Finder Find the Dipper Look for it on the sky
Presentation by : Presentation by David G. Iadevaia, Ph.D A P I2968 W. Ina Rd PMB 275Tucson, Arizona85741www.api-az.comastro@api-az.comCopyright 1999