EVANSTON, Ill. --- Italian astronomer Galileo Galilei first looked through a telescope nearly 400 years ago. What he saw during those first months -- the moon, satellites of Jupiter and phases of Venus -- continue to invoke wonder in the modern observer.

The public is invited to follow in Galileo's footsteps Saturday, April 4, and look through Northwestern University's powerful and historic Alvan Clark telescope at the Dearborn Observatory, 2131 Tech Drive, Evanston campus. The free special event will be held from 8:30 to 11:30 p.m., rain or shine.

Visitors will be able to see the waxing gibbous moon and Saturn, weather permitting. The open house celebrates "100 Hours of Astronomy," a worldwide effort to encourage telescope sky gazing, part of the International Year of Astronomy.

The Northwestern program also includes live webcasts of 100 Hours of Astronomy events from other parts of the world and informal presentations by Northwestern astronomers, who also will answer questions about astronomy and the observatory.

The dome of the Dearborn Observatory is not heated; visitors should dress appropriately.

The observatory also is open to the public every Friday from 9 to 11 p.m. (These summer hours begin April 3.) The first hour is by reservation only for groups; the second hour is for walk-ins, based on space availability. The observatory is available other evenings for private viewings. Call (847) 491-7650 for reservations.

More information about the April 4 event, including a campus map, can be found online.