Geo answer

The World
The World

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.


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.

Here now, far less than a light year away, is the answer to the Geo Quiz.


Thousands of people are gazing up at the stars this month — to help out with a science project. It’s called the Great World Wide Star Count, and one of its objectives is to map worldwide light pollution.

Schoolchildren, and amateur scientists around the world are being encouraged to look for specific constellations and then post their observations online. Participants in the Northern Hemisphere will look for the constellation Cygnus, while those in the Southern Hemisphere will look for the constellation Sagittarius.

Cygnus starCygnus star

To participate, check out this star count website that’s part of the Windows to the Universe project at the University Corporation for Atmospheric Research (UCAR) based in Boulder, Colorado.

Listen to our interview with the project’s coordinator Dennis Ward. He says there are 5 steps to participate:

1. Determine which constellation to observe.
2. Find that constellation at night an hour after sunset (about 7-9pm local time)
3. Match your nighttime sky with one of our magnitude charts
4. Report what you see star count website
5. View results of this international event.

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