Remember this Date: March 4, 1979

The Day We Discovered Life in the Universe

Voyager 1 Image of Io. Release Date: April 5, 1979; Image Source: NASA (Public Domain); Credit: NASA/JPL/CIT

We know things move in the universe, but for all the pictures we’ve taken, we’ve never really seen the kind of animated movement only live action can offer. That all changed on March 4, 1979 when Voyager 1 flew past Io, Jupiter’s closest Galilean moon and one of the four Jovian satellites discovered by Galileo that have captivated our attention over the past four centuries. Of course, we might have discovered this six years earlier if not for a glitch. In December 1973, Pioneer 11 offered the first close-up glimpse of Io, revealing a rocky surface, a thin atmosphere and radiation belts. Unfortunately, according to the NASA Publication Pioneer Odyssey, of the thousands of commands sent to Pioneer 10 during the 24 days of its Jupiter encounter, only one was lost due to those radiation belts – the one including the close-up pictures of Io.

According the NASA release associated with the above image, the picture,  a special color reconstruction, shows one of the erupting volcanoes on Io discovered by Voyager 1 during its encounter with Jupiter on March 4 at about 5:00 p.m. The spacecraft sat a mere 310,000 miles away as it captured the 60 mile high plume, representing the first evidence of an active extraterrestrial volcano. NASA explains the “method of color analysis allows scientists to combine data from four pictures, taken in ultraviolet, blue, green and orange light. In this picture one can see the strong change in color of the erupting plume. The region that is brighter in ultraviolet light (blue in this image) is much more extensive than the denser, bright yellow region near the center of the eruption. Scientists will use data of this type to study the amount of gas and dust in the eruption and the size of dust particles. Preliminary analysis suggests that the bright ultraviolet part of the cloud may be due to scattered light from very fine particles (the same effect which makes smoke appear bluish).”

Astronomers believe tidal heating induced as Io orbits Jupiter causes Io’s volcanic activity. Spewing sodium and sulfur into its thin air, the volcanic eruptions are even now shaping the Io’s surface. Voyagers 1 and 2 discovered seven erupting volcanoes on the moon’s dazzling red-orange surface. Unlike their Earthly counterparts, rather than expelling 2,000° F molten lava, these volcanoes eject molten sulfur at only a few hundred degrees.

Io – and its active volcanoes in particular – remain one of the biggest surprises of mankind’s initial decades of space exploration.

We say “a picture is worth a thousand words.” The pictures of these natural phenomena have perhaps inspired many more. Plato (in Timeaeus) ties together the sense of sight with what was later to become the study of astronomy:

“God invented and gave us sight to the end that we might behold the courses of intelligence in heaven, and apply them…”

We can spy in the night sky – depending on the time of year – several of these nominees with the unaided eye. Others represent spectacular deep sky objects whose true beauty can only be revealed once the photographic plate has remembered far more photons than the human eye can ever hope to collect in an instant.

The Original Nominations

The following candidates were nominated under the Sights category. Highlighted candidates have a separate description page already posted to this site. To view any highlighted nominees, place your cursor anywhere over the text of the nominee and click (pop-ups must be enabled on your browser):

Antares
Andromeda Galaxy
Centaurus A
Crab Nebula (M1)
Great Nebula (M42)
Earthrise
Evening Star (Venus)
Halley’s Comet
Hubble Pillars of Creation in Eagle Nebula
Hubble Ultra Deep Field
Hyades Cluster
Io erupting
Jupiter’s Red Spot
Magellanic Clouds
Orion et al (Rigel, Betelguese, M42)
Perseid Meteors
Pleiades Cluster
Polaris
Quasars
Ring Nebula (M57)
Saturn’s Rings (Voyager 2 Image)
Sirius
Summer Triangle – (Vega-Altari-Denab)
Tycho’s Star (1572 Nova in Cassiopeia)
Ursa Major
Whirlpool Galaxy (M51)

Not all the nominees made the top 100. Still, we’ve tried to include a short write-up on each of them. Any nominee that finished in the top 100 greatest images and imaginations in astronomy and space exploration will have its rank listed in the upper left hand corner of the specific page devoted to that nominee.