Crux and the Milky Way from Easter Island

March 24, 2011

Crux and the Milky Way from Easter Island

: Wally Pacholka, Wally's Home Page
Summary Author: Constance Walker; Wally Pacholka

The constellation Crux or Southern Cross, shown at extreme top center above, lies within the stream of stars that makes up the Milky Way (lower left to top center). For the Southern Hemisphere, this is one of two constellations new to the GLOBE at Night campaign. The sky above Easter Island, where the image was taken, is so dark there’s a wealth of stars visible to the naked eye. However, for at least half of the world's population that lives in cities, the brightest stars in a constellation may be the only ones they can see because of light polluted skies.

The GLOBE at Night campaign asks the public to be citizen scientists during its two-week campaign and to make very easy measurements of the night sky brightness. First, you stand outside for ten minutes to allow your eyes to become adapted to the dark, so that you can see the stars better. Next, you match the appearance of a constellation (Leo in the Northern Hemisphere and Crux or Leo in the Southern Hemisphere) with simple star maps of progressively fainter stars. Then you submit your measurements online; including the date, time and location of your observation. After all the campaign’s observations are submitted, the project’s organizers will release a map of light-pollution levels worldwide. These measurements are used for research later in comparison to wildlife, health, energy consumption and cost, among other things.

Starting this year, citizen scientists can also submit their measurements in real time if they have a smart phone or tablet. The web application for this can be found here. With smart phones and tablets, the location, date and time are put in automatically. As always, the campaign urges people to take more than one measurement. To help with that, the campaign is piloting a new program called "Adopt-A-Street". The aim is for people to adopt a different major or semi-major street and take measurements every mile or so for the length of the street (or for as long as they can). The resulting grid of measurements of the city will help scientists, governments, policy makers, and individuals to track and address light pollution issues.

Please consider joining the campaign from 8 p.m. to 10 p.m. local time March 22 through April 4 in the Northern Hemisphere and March 24 through April 6 in the Southern Hemisphere. Your measurements will make a world of difference. Note that the Large Magellanic Cloud is at lower right. At bottom, in silhouette, are the mysterious Easter Island stone statues (Moai).