Stephen Hawking is a strong proponent of colonizing outer space because, our destruction of the planet notwithstanding, the sun happens to have an expiration date. It's a true and sobering thought, but it doesn't mean we shouldn't do what we can to better preserve our (currently only) home while we have it.

Celebrate Earth Day this year by making some lasting eco-friendly changes in your lifestyle, by starting a co-op organic garden in your community, or by learning about what the problems are and what you can do. For a more thorough list of events, visit rochestercitynewspaper.com and search "Earth Day," but here's a quick variety of sparkly happenings. P.S.: Earth Day falls on National Turnoff Week, so snub the tube, read or play games by candlelight, and frolic outdoors while the weather allows it.

If information is what you're after, attend one or many of the following lectures. Tapas & Talks will be offered at Nazareth College (4245 East Ave.) on Thursday, April 22, at 6 p.m., featuring "Water, Water Everywhere, But is it Safe to Drink?" by chemistry professor William Lammela, and "China's Environmental Crisis: Bad Air, Bad Water, Bad Coal, Bad Policy?" by history prof Nevan Fisher. The free event will take place in Medaille Formal Lounge; for more info call 389-2472, or visit naz.edu. The Sierra Club's Environmental Forum also falls on April 22, and will be held at the First Unitarian Church, 220 S Winton Rd. at 5 p.m. This year's highlights include a lecture on "Transitioning to Sustainable Communities," a community fair, and dialogue. For more info, visit newyork.sierraclub.org/rochester.

The Landmark Society's 24th Annual Preservation Conference, "Saving the Past, Sustaining the Future," will educate on how maintaining and restoring old structures saves money, resources, and revitalizes neighborhoods. The conference will take place Saturday, April 24, 8 a.m.-5 p.m. at Palmyra-Macedon High School, 151 Hyde Parkway, Palmyra. Attendance fees range from $45 to $75 (registration required), with an additional fee for a boxed lunch. Call 546-7029 x10 or e-mail mail@landmarksociety.com for more information. On Wednesday, April 28, 7-9 p.m., the Reshaping Rochester lecture series continues with "The Unhealthy Consequences of Sprawl" at The Strong National Museum of Play, 1 Manhattan Sq. Tickets are $15-$20, and more info can be found at rrcdc.org. And on Saturday, May 1, The Rochester Zen Center, 7 Arnold Park, will host "Turning Toward the Earth," an environmental symposium. The event runs 9 a.m.-5 p.m., and costs $40-$60. For more info, visit rzc.org or call 473-9180.

Kids can get in on the initiatives too. Greece Barnes & Noble, 330 Greece Ridge Center Dr., will offer "Earth Day Exploration" on Thursday at 2 p.m., with free green activities for ages 5 and up. Or be a water scientist at the Rochester Museum and Science Center through Sunday, daily noon-4 p.m., with a bunch of educational hands-on water activities and science shows, which are included with regular museum admission of $10-$12. Visit rmsc.org or call 271-4320 for info.