Here's your chance to be the first person on Earth to spot the new moon when it makes its appearance Tuesday night. Your efforts won't be on a par with the discovery of a new planet, but it will help science nonetheless.
Scientists know the position of the moon at any given time precisely enough to send six spaceships across 250,000 miles of space and land on the exact lunar spot they chose.But they can't predict the exact time or geographic location at which the young crescent moon will first be spotted. And that's where you come in.
The U.S. Naval Observatory asks participants in the Moonwatch to be outside where there's a clear, flat western horizon and to watch from about a half hour to an hour after sunset.
"Please do not use binoculars or telescope," the observatory says. "A good horizon is essential since the moon will be best visible when it is roughly 2 degrees to 5 degrees above the true horizon."
Astronomers will compare the Moonwatch observations with their theoretical calculations to improve their ability to predict the time and location at which the moon first becomes visible.
Write to the Naval Observatory at 34th and Massachusetts Ave. NW, Washington, D.C. 20392, about what you saw and when you saw it. A sketch showing the position of the crescent with respect to the horizon will be welcome, the observatory says.
The observatory's Moonwatch 1988 elicited information from more than 2,000 observers, ranging in age from 4 to 92 years. Some turned the occasion into family outings. Their findings were published in Sky and Telescope magazine.
Be warned: The new moon usually does not appear until the second evening but it can be visible under certain conditions.
There are no prizes and the observatory offered only this hope: "May your sky be clear!"