Sky Watch: Southern skies, round planet

The Earth is round.

Now, while most of my readers will find this to be no great revelation, there are those who choose to believe otherwise. There is, in fact, a small organization of "free thinkers" who insist that our world is flat and motionless and that all evidence to the contrary is bogus and a conspiracy to negate the words of the Bible. It's called the Flat Earth Society, and has been around off and on for more than half a century.

One of the proofs of their claim was offered by the group's former president Charles K. Johnson; it states that his Australian-born wife Marjory never hung by her feet while Down Under, and that people there walked upright just like those in the United States.

Hard to argue with such rigorous scientific analysis!

Well, folks, I'm in Australia this week leading a group of excited sky watchers on a journey to experience a total eclipse of the sun, and I can swear that I am as vertical here as when at home in California. Of course, I might just be part of the conspiracy too.

Many proofs exist that our planet is round, but there's one I'm reminded of every time I'm on such a trip. The calculations that predict the solar eclipse -- and where we need to stand to see it -- are based on the premise that our planet is spherical. If this weren't true, the numbers would be wrong, and people would have long ago criticized me for leading them all this way only to miss the show.

A good demonstration of our planet's roundness appears to Northern Hemisphere stargazers low in the southern sky at night. The farther south you live or travel, the higher the southernmost stars appear. In fact, sky watchers in the Southern Hemisphere can see these stars high overhead; this is a direct result of the roundness of our planet.

Tonight after dark, go outdoors and see if you can find these southern star groupings.

The highest, and easiest to spot, is Piscis Austrinus, the southern fish, marked by Fomalhaut, the brightest star in the area. This is an ancient constellation often depicted as a fish lying on its back and drinking water pouring from the jars of Aquarius.

Just below -- and visible only if you have a dark sky and very low southern horizon -- is Grus, the Crane, a Southern Hemisphere constellation introduced by German astronomer Johann Bayer in his 1603 star atlas Uranometria.

To its right lies Microscopium, the microscope, one of several constellations introduced by Abbe Nicolas Louis de Lacaille, who mapped the stars of the Southern Hemisphere from the Cape of Good Hope from 1751 through 1753.

And finally, to the left of Grus appears Sculptor, another constellation created by the good abbot to help fill in part of the relatively empty Southern Hemisphere sky.

While these may be tough to find for Northern Hemisphere stargazers, 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 demonstrate what people have known for millennia: the Earth is round.