Half Moon and Half Earth

The view from Voyager when Jimmy Carter was President and John Lennon was making music

Long before Photoshop was invented there was a way of producing images like this.

Magritte: La Reproduction Interdite

It involved sending a spacecraft with a camera a long way into space. As NASA explains:

This image of the Earth and moon in a single frame, the first of its kind ever taken by a spacecraft, was recorded on Sept. 18, 1977, by Voyager 1 when it was 7.25 million miles from Earth. The spacecraft launched on July 20, 1975.

Voyager 1 is now outside the solar system and heading inexorably away – the most distant man-made artifact in the universe.

It carries a plaque with some very basic information about human beings and our earth, in case it’s ever encountered by intelligent life elsewhere.

If that ever happens, presumably it’ll be far in the future.

Voyager 1: in 2011 we put more powerful computers in dish-washers

Will human beings have made a terminal hash of our global habitat by then?

If so, this little object may be just about the only remaining testimony to the existence, at one time, of half-intelligent life on planet earth.

I hope we do better, but maybe the cosmos is set up with this built-in constraint?

If an aspiring intelligent species can’t make a go of one very nice planet, it may be just as well if it’s ability to screw up the wider universe is limited to littering with a few tokens of space junk.

Io - Jupiter's closest moon (photo via Galileo Project, JPL, NASA)

If Hell exists – and if it’s located inside our solar system – Io is a likely candidate.

The innermost satellite of Jupiter, it has a thin sulphorous atmosphere, more volcanic activity than anywhere else for lightyears, it’s bathed in radioctivity at the lethal level of some 3,600 rem per day and has a magma ocean estimated to reach 1,200 degrees Celsius. Not a great place to spend a vacation – but strangely beautiful in its own way, nonetheless.

Heaven, on the other hand, must be a sunny, blue, watery planet with a finely-tuned atmopshere like a warm blanket that’s just right.

Planet earth, for example.

Another gem from APOD, which provides this explanation about the satellite Io:

The strangest moon in the Solar System is bright yellow. This picture, an attempt to show how Io would appear in the “true colors” perceptible to the average human eye, was taken in 1999 July by the Galileo spacecraft that orbited Jupiter from 1995 to 2003. Io’s colors derive from sulfur and molten silicate rock. The unusual surface of Io is kept very young by its system of active volcanoes.

The intense tidal gravityJupiter stretches Io and damps wobbles caused by Jupiter’s other Galilean moons. The resulting frictionIo‘s interior, causing molten rock to explode through the surface. Io’s volcanoes are so active that they are effectively turning the whole moon inside out. Some of Io‘s volcanic lava is so hot it glows in the dark.

Io in truecolor via the Galileo telescope

In Greek mythology, Io was a nymph who attracted the eye of Zeus. Turned into a heiffer for her own safety, she was tormented by his jealous wife Hera with a gadfly that pursued her across the ancient world. On the way Io had a close encounter with Prometheus and eventually found happiness in marriage to an Egyptian King.

Tangling with Greek Gods never made for an easy life.

One great thing about the 21st century: humanity can appreciate the cosmos like never before.

Along with increasingly affordable high-powered telescopes, a new artistic field has come into being: astrophotography.

Connecticut-based Robert Gendler is one of the best atsrophotographers in the world; his work has been featured 63 times on NASA’s Astronomy Photo of the Day website.

Gendler’s latest APOD contribution is this succulent image of the Triffid Nebula. Cosmic eye-candy. Enjoy!

The Triffid Nebula; photo by Robert Gendler