Talk:StarChart

This program can be much more than just a map of the night sky. Offhand, I can think of a whole bunch of things it can demonstrate. A couple of less-obvious ones are:

How the human mind sees patterns in what is actually random arrangements of points. (The constellations.)

That bright stars are less common than dim ones. (Because to be bright, a star has to be either unusually luminous or unusually close.)

Which pairs of stars rise or set at the same time depends on your latitude. (This is how the Polynesians navigated, I'm told.)

Some more obvious ones:

The earth rotates once in 24 hours. Which makes the sky appear to move at a rate of 15 degrees per hour from east to west.

The earth goes around the sun once in 365.242 days. Which makes the sky appear to move at a rate of about one degree per day from east to west.

The sun, the moon and the planets follow roughly the same path against the stars (the ecliptic), but they move at different rates. And because the earth goes around the sun, too, some planets appear to reverse direction at times.

Changing to a different longitude is like changing your clock.

Unless you're on the equator, some stars never set.

Davewa 16:07, 22 May 2008 (EDT)