One is Astronomy Week, which culminates with Astronomy Day on Saturday, April 21st. Astronomy clubs, planetariums, and other groups of sky lovers are out in force to draw public attention to the science and the hobby through exhibits and activities at urban centers. The dates are chosen each year to coincide with the appearance of a young Moon in the evening sky, and during Astronomy Week public star parties abound. The event got its start 34 years ago in northern California, and since then the event has grown to include groups worldwide.
Not all local clubs have organized Astronomy Day activities, but a great many do. To find a participating group near you, check out SkyandTelescope.com's extensive listing of astronomy clubs, planetariums, and other organizations.
Also ongoing is National Dark-Sky Week. Founded in 2003, this observance highlights the growing concern over light pollution and its degrading effect on the nighttime environment — especially the visibility of stars. According to NDSW founder Jennifer Barlow, more people need to realize how much poorly designed and excessive outdoor lighting exists.
One city that recently celebrated darkness was Sydney, Australia. Government officials and environmental groups there spearheaded a citywide "Earth Hour" on the evening of March 31st, during which some 50,000 households and 2,000 businesses voluntarily dimmed their lights. "It's an hour of active, thoughtful darkness," noted Australian actor Cate Blanchett, who was on hand for the dramatic demonstration. Organizers hope that Earth Hour will be observed throughout Australia next year.