Taare Sadak Par
[The discussions in our related yahoogroup,
http://groups.yahoo.com/groups/Astronomy_Activities_2009/
on this topic, are summarised here. ]
[The Taarewiki is the location where all the collaborative discussions and observations from this program, are being archived.]
This is a program where we are hoping for collaboration and help from every individual, organisation or group that has an interest in Astronomy, to spread the word, observe "Taare Sadak Par", and help quantify light pollution in different regions of the country.
Light Pollution? What is that? Would quite likely be a question asked by many, in India. There has not been much of awareness about this aspect, in India. We may perhaps be quite unaware that some of the worst sites of light pollution exist in India. Perhaps, the monster has only just started rearing such a monstrous head in our cities. Perhaps, some of the damage is reversible on short timescales with timely action. We really do not know any of this. We will know the monster a little better if we know it quantitatively. Knowing it quantitatively, might also help us fight it better.
Why should we bother about Light pollution? Do problems related to air and water pollution not need more urgent action and civic participation? Yes, perhaps light pollution might not be as immediately life threatening as air or water pollution. If the air we breathe or the water we drink is slowly getting poisoned, we have to tackle that very urgently.
We have to look at a very simple way of quantifying light pollution, so that observations can be submitted by everyone - by someone who is not even a beginner interested in sky observations, but, is just willing to look up at the sky once or twice for this project or by a beginning observer of the skies, as well as by seasoned amateur astronomers.
We need therefore to pick up those regions of the sky that have easily recognisable patterns of stars, which contain stars in widely differing magnitude ranges. (See here for a beginner's description on magnitudes of stars)
We can pick up a region of the sky overhead, for each month, to better quantify light pollution, in directions away from very local annoyances.
However, for the later half of March, when this program is just starting, it might be easier to start towards the South-West and use the best known of all patterns in the sky - the constellation of Orion.
From regions that have rather bad marks related to light pollution, the sky in this direction might look like this :-
(The image has been prepared for late March Delhi skies, after sunset. Small changes in orientation would be required for locations different from this, but, the Orion region should be visible and unmistakable, seen from any region in India)
Slightly better skies, from regions not so very badly off with respect to city lights :-
Even better, what the skies might have been like a few decades ago, with just a few stray sources of light pollution.
And finally, the skies that nature gave to us unasked and that we have driven away from us, for the most part.
Every location that we visit during this period, why don't we attempt to quantify which category it belongs to, from any of the above possibilities?
One way to put some numbers into this quantification would be to make a table of magnitude ranges
| 0.0-0.5 | 0.5-1.0 | 1.0-1.5 | 1.5-2.0 | 2.0-2.5 | 2.5-3.0 | 3.0-3.5 | 3.5-4.0 | 4.0-4.5 | 4.5-5.0 | 5.0-5.5 | 5.5-6.0 |
| Yes? | Yes? |
(The above table is assuming that no skies in the world are as badly polluted as to have only negative magnitude stars visible, but, who knows, there might be such terrible pockets too).
We look at the sky in the south west direction and look for the stars that are labeled in this figure.
(Figure is yet to be refined and completed)
If we find the stars in the magnitude ranges that are in the first row of the table above, we note that in the second row. Go to fainter and fainter stars until we are forced to mark a sad "No" in the second column - that is what we have done to our own neighbourhood.
Of course, there may be many local variations, a single data point for a given location and given time would not exactly quantify the light pollution from that region, We would need many data points to get a trend of light pollution from a single location. Which is the reason why we need observations from many people - from anyone who would be willing to participate in this "Taare Sadak Par" program. Please do post to nehruplanetarium (@) gmail.com and also to any other group organising these observations, so that everyone's efforts can be compiled together.