First Open Nights Observer Gives Big Dipper 50,000 Years in Present Form

Predicting that the Big Dipper in the northern sky will lose its form within 50,000 years, due to a shifting of the stars, Sidney W. McCuskey, assistant in Astronomy, opened the annual series of Open Night lectures at the Observatory last evening.

"Since 1718 when the famous English astronemer Halley first noted that Areturns and Sirius, two of our brightest stars, had changed position in the sky since the times of Piolemy and the other ancients, astronomers have been collecting all available data relating to stellar speeds and the directions in which the stars travel," said Mr. McCuskey.

The Plelades

"They have found that some stars such as the Pleisdes, which are now visible in the late evening sky, prefer to travel parallel to one another as a group. We find the Plelades going along moderately at eight miles per second.

"It is also of interest to know that the familiar Big Dipper in the northern sky will no longer have a dipper form in fifty thousand years; the stars will have shifted their positions.

"Other stars choose to move in a more or less haphazard way. Still, among these motions we find certain regularities, an explanation of which leads us to the interesting idea that perhaps our whole Milky Way system of stars is rotating about a center in much the same way that the earth and the other planets revolve about the sun.

High Speed

"Further evidence to this rotation is given by considering the 'speeders' among the stars. We find individual cases of these traffic violators in which the culprit has been caught traveling between one hundred and two hundred miles per second. All of the high speed stars, moreover, prefer to avoid certain regions of the sky.

"These facts, and the ingenious methods of deriving them, form one of the most interesting phases of modern astronomy."

Other lectures in this series will be given tomorrow, on "The Planet Mars." Friday, on "Photography in Astronomy," and next Monday, on "New Stars for Old," each at 7:30 o'clock. Tickets are free and must be obtained by sending a stamed, self addressed envelope to the Harvard Observatory.