Possible Duplicate: Why does the moon sometimes appear giant and a orange red color near the horizon? Why does the moon look bigger at horizon or skyline than at other times e.g. at ...
For helping with judging NLC candidates (are they NLC or not) I have a set of formulas to calculate the minimum altitude (in km) of the candidate given an observed altitude (in degrees) of the ...
It is said one should avoid staring at Sun as it can damage the eyes, but it is also said that one should not come out in sun during eclipse as it emits dangerous rays. Is that true? If yes, why?