Your Best Seat for the Eclipse

The last total eclipse of the millennium will also be the most watched in history--regardless of the weather. Although overcast skies can spoil months of travel plans, several Webcasts from along the path of totality--including a cruise ship in the Black Sea linked by satellite to NASA--almost guarantee Web surfers a clear view of the 11 August event.

Approximately once a year, the moon passes directly between Earth and the sun, casting a shadow somewhere on the planet. But total eclipses--when the sun is completely hidden behind the moon--are rare because they can only be spotted from a narrow band of moon shadow called the umbra. On Wednesday, the 110-kilometer-wide umbra will sweep eastward across the North Atlantic at nearly 2400 kilometers per hour. During the day it will sail just south of London, Paris, Istanbul, and on into India before disappearing with the setting sun. Because totality lasts less than 3 minutes at any one location, bad weather is always a concern to eclipse hunters. All it takes is one cloud to ruin a once-in-a-lifetime chance, so many eclipse-watchers are hedging their bets with the Internet.

Observing stations from the United Kingdom to India will transmit live video of the eclipse to a number of Web sites. NASA has a video feed from the deck of the Black Sea cruise liner Marco Polo and will hold a live chat throughout the eclipse with astronaut Ron Parise. "Users will see different windows showing a satellite picture of the shadow crossing the Earth, live responses from the online chat, activity on the deck of the ship, and multiple images of the eclipse," says NASA outreach computer specialist David Beverley. Several links to other eclipse broadcasts are available at the Sky & Telescope site.

Many sites require different software, so Beverley encourages surfers to visit the sites before the actual eclipse and download what they need. Barring technical glitches, the show will be hard to stop. "God would have to conspire in a very nasty way" to completely block the eclipse at all the sites, says Sky & Telescope associate editor Alan MacRobert.