The year 1997 began on a somber note, just days after the death of astronomer Carl Sagan. In many ways, though, the year's events went on to celebrate Sagan's life. There were steady advancements in a variety of disciplines. But perhaps the most stellar happenings of the year took place in Sagan's own specialties, namely astronomy, cosmology and space science.

HALE-BOPP

As if in tribute to Sagan, Comet Hale-Bopp blazed across the early summer skies, its fiery tail observed by the most sophisticated observatories and millions of amateurs--armed with telescopes, binoculars or the naked eye. 1997 also marked the 40th anniversary of the Space Age, which began officially when a startled world awakened to beeping signals from the Soviet Union's Sputnik I on October 4, 1957. In the years that followed, Sagan was a pivotal in the conception and planning of unmanned space probes, many of which are still returning important data.

Two spacecraft inspired by Sagan, Voyager I and Voyager II, which were launched August 20 and September 5, 1977, arrived at halfway points in their 40 year missions. Both reached the very fringes of the solar system in 1997, and headed into interstellar space. In their first decade, these vessels returned important images and data from Jupiter, Saturn, Uranus and Neptune. Since 1989, both have patroled the outer solar system. And in February 1998, Voyager 1 will pass the Pioneer 10 spacecraft, making it the most distant human-made object in the universe.

All of these spacecraft are equipped should they chance upon intelligent life elsewhere in the cosmos. Pioneer 10 carries Sagan's famous plaque, which bears human greetings. And both Voyagers contain a gold record describing the location of Earth and human civilization. (Perhaps DVD compact discs, which only came to market last year, would now be more appropriate.)

The search for alien life also continued closer to home. Early in the year, the Galileo spacecraft returned spectacular images of Jupiter's moons--including the most intriguing snapshots yet of the icy Jovian moon, Europa. The data showed that this tiny satellite bears a thin oxygen atmosphere and seeming oceans of liquid water--maybe capable of supporting life--beneath it's frozen crust.

SOJOURNER

And, of course, new results arrived from Mars--where humans always seem to want to find kindred life. Evidence of ancient Martian life--at least in the form microbes--continued to accumulate in 1997 from a Martian missionary, a meteorite found in Antarctica that is believed to have been knocked free from Mars 16 million years ago. The meteorite contains what some researchers believe are fossilized bacteria.

And on July 4, Mars Pathfinder plopped down on the Red Planet's surface and its tiny robot rover, Soujourner, ambled off to sample rocks and look for life. The landing marked the first visit to Mars since the mid1970s, when the Sagan-inspired Viking landers conducted a fruitless search for Martian life.