When we look at the sky in the night we see the sky scrolling as if we are moving and the whole sky seems to turn the hours around. This is because of the Earth’s rotation and by this phenomenon we see the rise and set of the stars. Earth’s movement in its orbit around the Sun also shows different portions of the sky round the year. We can understand this by watching daily changing position of stars above our head by standing at a static position on the Earth. A simple and handy device designed to watch the relative position of stars from a static point on the Earth is ‘Tara Ghadi’ (Star Watch).
The Tara Ghadi (Star Watch) consists of two major components – Star Wheel and Star Dial. Star wheel is fixed in the star dial in such a way that it can be rotated in the star dial. The star wheel is having the position of stars inscribed which is surrounded by the monthly calendar. Star dial is a time displaying tool with that the star wheel can be adjusted according to the particular day and time.
â— Tara Ghadi (Star Watch),
â— compass,
â— clock
1- First of all fix the calendar of star wheel with the time of the star dial
2- Hold the Star Watch above your head such a way that its north pointer projects outside and south pointer above your head
3- Now see the names and positions of stars visible in the star wheel and then watch the sky above your head to find stars and their similar position in the space.
4- Try the same activity in your region at different locations (different locations must be few kilometers away from each other) and try to derive inference regarding positioning of stars in the sky.
5- You can make a network of friends living in different cities and share the findings of star watch with each other.
â— You can record position of the stars seen above head in respect to time (hourly or daily basis)
.â— By compiling the monthly record you can categorize the stars most seen, least seen, longest seen, shortest seen etc.
You can make a record of the stars and planets seen in the sky in respect to time and place on the Earth. A record of constellations seen at different times and other celestial events can also be prepared to understand their timing and positions in the sky.
â— Positions of stars above us at a time
â— Timing & Frequency of appearance of a star in the sky
â— Direction of stars visible from a point location
â— We can find directions by observing position of stars
â— By practicing with Tara Ghadi now try estimating time (without a clock) by looking at the position of stars on a day. You can try estimating direction in the same way.
â— When compass or any other instruments were not available, how could sailors and travelers determine the directions for movement? Explain to your peers with example.
â— Why do stars in the sky seen blinking? Why not the Sun and the Moon are seen blinking same way?
â— Do the position of stars and their constellations affect us in any way?
Cropping Calendar: Our traditional agriculture practices involve planning of crops and cropping cycles based on star navigation (i.e. deciding the cropping calendar). You can interview the village elders to know about how they used to plan their activities based on star navigation and with your observations using Star Watch those practices can be verified and documented.
