Week of April 27 — May 3, 2014

The Earth is round.

Now, while most of my readers will find this to be no great revelation, there are always those who choose to believe otherwise.

Certainly, a number of proofs exist that our planet is round, but there's one I'm reminded of every time I lead a group of excited sky watchers to experience a total solar eclipse. The calculations that predict the eclipse — and where we must stand to see it — rely on the Earth being spherical. And if the calculations aren't correct, people would long ago have strung me up for leading them all that way only to miss the show.

Another demonstration of our planet's roundness appears to Northern Hemisphere stargazers low in our southern sky each night. The farther south you live or travel, the higher the southernmost stars will appear. In fact, stargazers in the Southern Hemisphere can see them overhead. This is a direct result of the roundness of our planet.

To find some of these this week, first locate the bright star Vega and the Red Planet Mars, midway up in the southeastern sky after dark, and look to their right.

The largest of all constellations is Hydra, the water snake. Hydra represents the hideous seven-headed monster killed by Heracles as the second of his Twelve Labors of ancient Greek mythology.

Hydra snakes its way across nearly 100 degrees of the sky — from the northern heavens just below Cancer well into the southern sky — and covers 1,303 square degrees of celestial real estate. Despite its immensity, Hydra is faint and contains only one fairly bright star. From mid-northern latitudes, however, we can see only part of this constellation.

Hydra is related to two nearby star groupings: Corvus, the crow and Crater, the cup. Corvus is an ancient constellation known by the Greeks as the bird that Apollo sent to collect a cool drink of water from a nearby cup. Having squandered his time, the crow instead brought back a water snake as his excuse for returning late. In anger, Apollo tossed them all into the same region of the sky where we can still see the water snake guarding the cup of water from the perpetually thirsty crow.

Along with Hydra, Corvus and Crater appear three other rather obscure southern star groupings. Highest of these is the constellation Sextans, the sextant, which was created and introduced by the Polish astronomer Johannes Hevelius in his posthumously-published 1690 atlas titled "Firmamentum Sobieski." He named it Sextans Uraniae to commemorate the large and beautifully decorated observation sextant he used to measure positions of stars.

You'll have to look much farther to the south — and very low against the southern horizon — to find Antlia, the air pump, and Pyxis, the compass — both of which were invented by the 18th-century astronomer Abbe Nicolas Louis de Lacaille who mapped the stars of the Southern Hemisphere sky from the Cape of Good Hope.

So the next time you take a long trip north or south, pay close attention to the stars of the southern sky. Their changing elevations will show you what sky watchers have known for millennia: The Earth is round.

Visit Dennis Mammana at www.dennismammana.com. To read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.