Looking back over the 25 years since the first Voyager launch on Aug. 20, 1977, the twin spacecraft are remembered first and foremost as our emissary eyes in deep space.

The photographs revealing Voyager's firsts -- among them the discovery of volcanoes on Jupiter's moon Io and a visit to Neptune -- kept earthlings enthralled for years. One of Voyager's most famous pictures is a view of Earth, called the Pale Blue Dot, taken in 1991 from more than 4 billion miles away.

"Scientifically, it didn't teach us a single thing," says Jurrie Van der Woude, a longtime image picker and processor at NASA's Jet Propulsion Laboratory, of the photo. "But historically, it's priceless."

In an interview last year, Van der Woude recalled how slowly photographs came back from the Voyagers, scrolling across a computer screen line by agonizing line. Impatient and needing to make decisions late at night so the world could see a photo the next day, he'd often choose a picture after seeing only 30 percent of it.

Behind the photography, though, are two remarkable space probes that have endured more than two decades of space travel and can still talk back (they might talk to ET, too, as you'll see below). So on this 25th anniversary, we present both a Gallery of Voyager images and the Top 10 Facts behind the making and operation of the spacecraft.

1

Hello!

Both Voyagers carry a greeting card of sorts in case any intelligent life is encountered. The message is inscribed on something akin to a phonograph record. But this 12-inch gold-plated copper disk holds pictures, as well.

The record contains sounds and images selected to portray the diversity of life and culture on Earth, all selected for NASA by a committee chaired by Carl Sagan.

There are 115 images and a variety of natural sounds on the record, along with music from different cultures and eras (alas, no Eminem, no Britney) and spoken greetings in 55 languages.

Each record is encased in an aluminum jacket and comes with its own cartridge and a needle. Instructions, in symbols, attempt to explain the origin of the spacecraft and indicate how the record is to be played. The images are encoded in analog form. To hear the audio parts as intended, ET will need to play the record at 16-2/3 revolutions per second.

It remains to be seen whether whoever finds it will deem the senders intelligent.

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