The Milky Way puts on a free show most every night.

Problem is light pollution from brightly lit cities can obscure all but the brightest stars. Now a team of atmospheric scientists is mapping light pollution around the world. It's polling anyone with a view of either one of two star constellations.

In the Southern Hemisphere, Sagittarius, stands out like an archer drawing his bow.

Sagittarius

But in the north, its another cluster of stars they're after:

"The constellation is located directly overhead shortly after sunset for Northern Hemisphere observers...it is in the form of a cross and is sometimes known as the Northern Cross. This constellation is in the middle of the summer triangle that's formed by Vega Deneb and Altair." (Dennis Ward, Great World Wide Star Count)

Ptolemy included this constellation in his early star catalogs. Ancients described it as a wide-winged bird, maybe a swan or a crane migrating south. It's brightest star is about 1,500 light years away.

The answer to our Geo Quiz is much, much closer.