BELLA LUNA

Soviet probe Luna 3 returned our first view of the far side of the moon, revealing odd, mountainous terrain.

The camera was triggered by a photo cell responsive to reflected lunar

light and used radiation-resistant film, which was developed, fixed, and dried on board. That same year, Soviet premier Nikita Khrushchev made a historic U.S. visit. Upon being denied a visit to Disneyland, he joked: "I ask, why not? What is it? You have rocket launching pads there?"

SHOOTING OUR MOON

It's the official end of the cold war, as jointly announced by presidents George H. W. Bush and Boris Yeltsin. And on its way to Jupiter, Galileo takes a closer look at our moon. The craft is outfitted with a 65-pound solid-state imaging system for the first multispectrum views of the satellite and clearer views of the poles and the far side. This north pole view was assembled from 18 images.

IT CAME FROM MARS

The first optical storage techniques--which would later create the compact disc--were developed in 1965, but data transfer was still agonizingly slow: Mariner 4 radioed these pictures over 134 million miles with a puny 10-watt radio transmitter at the rate of 81/3 bits per second. Each grainy image took 8 hours to receive, but the payoff was huge: surprising evidence of deep impact craters.

MARTIAN GROOVES

By the beginning of the 21st century, the Mars Reconnaissance Orbiter boasted a camera capable of imaging objects only a few meters across, revealing the diversity of Martian gullies. This crater, roughly seven kilometers across, features both rectilinear crater-wall troughs and sinuous grooves in the floor.

Explanations include erosion from seepage, melting of ground ice, or dry landslides.

SUNSHINE IN MY EYES

Vibrant brown and orange--just like a mid-decade knit polyester shirt--these solar portraits snapped from Skylab, the first U.S. manned observatory, allowed the outer corona of the sun to be seen clearly for the first time. This picture is color-coded by brightness; others documented the constant flickering of the corona and clarified the relationship between coronal holes and high-speed streams in solar wind.

A MILLENNIUM BALL

The two STEREO space-based observatories launched in 2006 capture ultraviolet wavelengths. Here, the sun, looking like an LED-encrusted crystal ball waiting for midnight in Times Square, shows a dark coronal hole visible in the lower right quadrant. STEREO observes solar storms and probes coronal mass ejections, which can disrupt satellites, endanger spacewalking astronauts, and even knock out earthly electric power.

LORD OF THE RINGS

Technology showed its dark side in March 1979, as the Three Mile Island power plant suffered a severe core meltdown, the nation's most serious commercial nuclear accident. That fall, Pioneer 11, the first craft to approach Saturn, discovered strong magnetic fields and took temperature readings suggesting that this cold planet glows with internal heat. The craft also detected two moons and a small ring that had never before been seen.

SATURNALIA

Global warming has replaced the China Syndrome as the number one energy worry in the United States, and Cassini delivers a whole world of new data on Saturn: rubble-pile moons, gaps in its famous rings, gorgeous photos of the pastel cloud cover, and possible reasons for its 900-mile-an-hour winds. Another find: massive electrical storms with thunderheads as big as the entire Earth.

ALL EYES ON IO

As Americans marvel over Alien and Star Trek: The Motion Picture, Voyager 1 beams back pictures stranger than science fiction. On Io, Jupiter's moon, researchers had expected to find craters but instead saw a tormented landscape of calderas and volcanic vents. It was a stunning find: Earth was not the only planetary body with an active interior. Io has lakes of molten sulfur and plumes of sulfur dioxide shooting hundreds of kilometers above the surface.

BY JUPITER

Two decades later, Galileo found a moon transformed, its surface remodeled by unrelenting volcanic activity. This seething volcanism is thought to be caused by the massive tides wrought by nearby Jupiter: The push and pull heats and liquefies the mantle of little Io, no bigger than Earth's moon. Meanwhile, science fiction remains more stable: Star Trek: Insurrection is on screens worldwide, and Alien vs. Predator, the computer game, is released.