How good is the night sky over your house? How well can you see the stars? How many stars can you see from your house? This month, a nationwide program and a worldwide effort attempt to find these answers and show you ways to improve your view of the No. 1 natural wonder of the universe: the beauty of the night sky. Many factors determine how well you can see the night sky. Natural weather patterns have an obvious effect. But even when clouds are not seen, high haze, which may well be invisible to you, can obscure many stars. Humidity causes air to scatter light, reducing the contrast between the "black” sky and the stars, making fainter stars harder to see and stars close together difficult to distinguish. What you might see as three stars on a clear, dark night may look like only one with high levels of humidity in the air. But by far the biggest thief of the night sky is light pollution. Light pollution won't cause physical or mental health problems. It won't give you cancer, but it is a cancer on the beauty of the night sky. It robs us of a natural treasure. The International Dark-Sky Association ( www.darksky.org) defines light pollution as "any adverse effect of manmade light. It is often used to denote urban sky glow.” The association describes several types of light pollution, including glare, light trespass and energy waste. All forms of light pollution deal with light going to places where it is not needed or wanted. Some forms of light pollution, while intended to make you safer at night, actually do more harm than good. From an astronomical point of view, all forms of light pollution add to sky glow, light that shines up above the horizon into the sky. That light does nobody any good: It won't increase your safety; it won't allow you to better see oncoming traffic or deter a burglary of your house or business at night. But it does take away the beauty of the night sky. When is the last time you actually saw the Milky Way? The first step is evaluating the problem. The international program Globe at Night sets out to do that. For several years, the organization has collected and analyzed observing reports from around the world. People like you go out during the Globe at Night evaluation period and count the stars visible from your house in a particular part of the sky. During the 2007 event, the program received 8,491 reports from 60 countries. This data, collected during several years, allows scientists to evaluate the state of the sky around the world. The 2008 Globe at Night event is under way. It started a week ago, but you still have time to participate. The observation window extends through Saturday. For details, go online to www.globe.gov/GaN. The Web site contains all the information you need to be involved. Students and families are encouraged to participate in a global campaign to observe and record the visible stars as a means of measuring light pollution in a given location. By locating and observing the constellation Orion in the night sky, people from around the world will learn how the lights in their community contribute to light pollution. Organize your own "star party” with friends and family and count the stars you can see in Orion. E-mail them to the program, and you will have participated in a major worldwide scientific study. Your contributions to the online database will document the visible nighttime sky. There are many steps you can take to help reduce light pollution. The International Dark-Sky Association offers tips, information, data and suggestions to help persuade others to join the effort. Another organization is asking people to participate in an hourlong experiment later this month to demonstrate the power of reduced light pollution. "Lights Out America” began as an effort to get San Francisco residents to turn out all their lights for one hour on a specific evening so that the whole city could experience the beauty of the night sky. It was so successful that it is being attempted as a worldwide program, based on a successful event that began last year in Sydney, Australia, called Earth Hour. Organizers asked all residents of Sydney to turn off all lights for a one-hour period. Originally, Earth Hour was a program designed to draw attention to the problem of global warming. Light pollution plays a role in global warming by wasting energy as it puts light where it does no good. What started as local events in San Francisco and Sydney have become a worldwide event occurring March 29 this year. Details can be found online at www.earthhour.org. Help protect the night sky and enjoy a sight like no other.
Sky notes•Daylight saving time begins at 2 a.m. Sunday. The time jumps from 1:59 a.m. in one minute to 3 a.m. as we "spring ahead” one hour. Spring itself officially begins at 11:48 p.m. March 19. On that date, also known as the vernal equinox, day and night are of equal length, and the sun will rise due east and set due west. The full moon for March occurs two days later, March 21. The equinox and the succeeding full moon together officially determine the date of Easter. By church rule, Easter occurs on the first Sunday following the first full moon after the vernal equinox. This is a complex rule, but it assures that Easter occurs in spring, just as it is supposed to. •Two-million, two-hundred-thousand years ago, a beam of light left a star in the Andromeda galaxy. Over eons, that light beam has crossed vast stretches of the cosmos, by the stars and through the gas clouds of the Milky Way galaxy and on to Earth. In the same stretch of time, humans have changed physically, mentally and psychologically, preparing for the day the beam of light would arrive and we could study and understand it. Come see the main feature in the Kirkpatrick Planetarium's Star Theater, "Lightyears From Andromeda.” Learn what the light beam "saw” on the way to Earth and how we have changed waiting for it. For show times and more information, call 602-3761. •The Oklahoma City Astronomy Club meets at 6:45 p.m. March 14. The public is welcome, and admission is free. •Planet visibility report: Mars and Saturn are the only planets to grace the evening sky. Jupiter rises around 3 a.m. and shines brightly in the predawn sky. Venus and Mercury are both low in the eastern sky before sunrise, but both are difficult to see in the morning twilight. New moon occurs March 7 and full moon is March 21, just before Easter. Wayne Harris-Wyrick is director of the Kirkpatrick Planetarium at Science Museum Oklahoma. Questions or comments may be e-mailed to email@example.com.