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.

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.


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.

Another low-budget National Aeronautics and Space Administration probe called NEAR snapped the closest images ever taken of a passing asteroid named Mathilde, a messenger from deep space dating to the birth of the universe. And another Sagan legacy, called Cassini, at last roared off on a seven year journey to explore Saturn and its moons. The October 15 launch took place in the midst of protests because the craft, like the Voyagers, obtains its electrical power from the radioactive decay of plutonium. Letters from Scientific American readers indicated they stood strongly behind Cassini and continued space exploration.

While planetary spacecraft busied themselves in Earth's back yard, the orbiting Hubble Space Telescope peered far out into the cosmos and back in time. The Hubble returned spectacular images of distant galaxies that document the birth and life of stars. And the telescope caught sight of the largest star ever discovered, now dubbed the Pistol Star. It appears to be 100 times larger than our sun and 10 million times brighter. Based on such images, astronomers are revising current ideas of how stars and galaxies form and age--and the ultimate fate of the universe.

Orbiting instruments aimed at our planet also returned some illuminating results. A radar satellite mapped the planet's last terra incognita--the Antarctic continent.And atmospheric scientists got their best look yet at recently discovered forms of lightning--including sprites and elves--that flicker high above the cloud tops.

Back on the ground, sparks flew between Kasparov and Big Blue, as the grandmaster threw down the gauntlet to IBM's chess playing computer. After winning one match and being beaten to a draw in three, Kasparov went down in defeat. Perhaps he should consider himself lucky. Semiconductor manufacturers continued to seek ways to milk Moore's Law--the idea that the number of devices which can be packed on a chip doubles every year or so--for the next generations of more powerful computers. Can thinking computers be that far off?

Or a Kasparov clone? No one can forget the debut this year of one Dolly--a quite normal looking lamb that was the first true genetic duplicate of a mammal. Dolly gambolled into a debate over the role of animals in scientific research and promptly fueled a debate of her own. The ethics of cloning animals--humans in particular--made front page news for weeks. Although moratoriums were declared on human cloning research, many saw Dolly as just the first out of Pandora's box. And they were right. Within months, commercial animal breeders were churning out a veritable barnyard of cloned livestock.


Other changes were taking place on the farm in 1997. The emergence of new and more virulent food-borne infections shook many people's faith in the safety of the food supply. Following several outbreaks of food poisoning caused by E. coli O157:H7 and the recall of tons of contaminated ground beef, support swelled for using irradiation to destroy food pathogens; in November, the Food and Drug Administration approved the process for red meat--a source of food poisoning and more recently, Mad Cow Disease. Meanwhile, the Nobel Prize in medicine was awarded to Stanley B. Prusiner of the University of California, San Francisco, for his discovery of prions, the agents believed to be responsible for Mad Cow Disease and a number of inevitably fatal human diseases.

The physics Nobel Prize went to investigators who discovered ways to use lasers to immobilize single atoms in "optical molasses." On other fronts in 1997, high-energy physicists continued their search for the tiniest fragments of matter and were hot on the trail of the leptoquark. In the fuzzy world of quantum mechanics, researchers at last proved that teleportation is possible--at least for photons.

Weather watchers kept their eye on El No, the maverick Pacific Ocean current that exerts a powerful influence over global climate.The oceans' strongest advocate, Jacques Cousteau, died in June as oceanographers continued to make important discoveries. Scientists aboard the international oceanographic drillship, JOIDES Resolution, brought up cores from the seabed off the coast of Florida that are the clearest evidence yet that a huge meteorite impact caused the mass extinction at the end of the Cretaceous. Other cores from the continental shelf off New Jersey provided a new picture of sea level changes during the Ice Age.

Still-feisty environmental activist Barry Commoner celebrated his 80th birthday at the Seaman's Institute Church in New York City, vowing to continue his battle against environmental toxins and greenhouse gases. And the issue of forestalling global warming by limiting greenhouse gases took center stage as representatives from more than 160 nations attempted to forge consensus in Kyoto, Japan in December.

In the end, 1997 went out with neither a whimper nor a bang, but instead, a roar. Based on computer models of a recently discovered fossil, the simulated the call of a long extinct dinosaur known as Parasaurolophus, the "trombone" dinosaur, sounded the final note.