GreaterSkies builds for you a beautiful, high-quality PDF file with a map of the sky as seen from a particular place at a given time.
For example, the sky as it was when you were born, over the place where you were born.
It can be a great personalized present, or a way to keep a memorable moment.
You choose the price, with a minimum of $1 and a maximum of $100. You also choose how much of the money you pay will be given to one of two worthwhile charities.
GreaterSkies is starting, and I don't know how this is going to play out: every time you pay for a poster, I store how much you paid, how much you intent to give to charity, and to which one. Then at the end of the month I'll make a money transfer to the two charities.
All the stars up to magnitude 9 that were visible are plotted, with an approximation of their actual colors and with an area corresponding to their magnitude. This is usually around 15000 stars. Planets, moon and sun are also shown, as well as constellations and star names.
The stars, position and colors come from the great HYG database.
The computation of the positions and the generation of the map is done in Common Lisp. The positions should be accurate for dates between around 1900 and 2100. I will release as open source the code that produces the charts as soon as I clean it up.
It is fun, it can be done, and it might make money both for worthwhile causes and for me. It has also been a great way to explore the great Amazon Web Services, on which everything is hosted.
I hope you enjoy it,