The Why Files The Why Files --

Star struck! The International Year of Astronomy

Celebrating the International Year of Astronomy!

By Jove! 400 years ago, Galileo Galilei, a founding father of astronomy, aimed his home-made telescope at Jupiter, and saw four moons. Galileo did more than get a curb's-eye-view of some sparkling new real estate: He produced evidence for the revolutionary notion that the planets did not orbit the Earth, but rather the sun.

What would Galileo think?

The galaxy super clusters surrounding the Milky Way look like an oval splatter painting.
Photo: NASA
This panoramic view shows galaxies beyond the Milky Way in the near-infrared spectrum. These galaxies are color coded by redshift -- by how fast they are receding from us as the universe expands. Blue are the nearest galaxies; green are intermediate; red shows the most distant sources. Larger numbers indicate faster recession.

We now realize that our solar system is an itty-bitty backwater of a big, boring galaxy that is, in turn, an infinitesimal fraction of a super-sized universe. But Galileo's observation helped proved that Nicholas Copernicus got the neighborhood right: Earth, no matter how unchanging it might seem, does circle the sun.

Equally unchanging is the danger of speaking truth to power, and as a reward for advancing physical science, the Catholic church tried Galileo for heresy. Galileo died under house arrest in 1642, a scant 350 years before Pope John Paul II “expressed regret for how the Galileo affair was handled, and officially conceded that the Earth was not stationary.”

A drawing of an earth-centered solar system with illustrations of angels surrounding it
In the 2nd century A.D., geographer Claudius Ptolemy placed Earth's northern hemisphere at center of the heavens, with the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn in separate rings. Ptolemy reserved the outer circle for the stars, represented as zodiacal constellations. Placing the sun at the center of the solar system makes the whole thing simpler -- and more realistic. Muchas gracias, Copernicus and Galileo!

Look upward, angel

With or without this ecclesiastical okay, astronomers on our watery planet are celebrating the International Year of Astronomy on the 400th anniversary of Galileo’s epic telescopic exploits.

In Galileo's memory, the Why Files will showcase two new astronomic achievements, and ask then whether we can prevent the stars from disappearing behind a haze of light pollution.

Cynics might ask "What has astronomy done for me lately?" but we applaud Galileo and his many successors for revealing a universe that is far more violent, ancient and downright oddball than even Ptolemy could have imagined.

Water, water, but not a drop to drink

Terry Devitt, editor; Nathan Hebert, project assistant; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive

©2017, University of Wisconsin, Board of Regents.