Week of October 17-23, 2021

It was during the early years of the 17th century that the Italian astronomer Galileo turned his new optic tube skyward.

While many people believe that Galileo invented the telescope, this just isn't so. It most likely came from Holland decades earlier and had been used to help spot approaching ships long before the eye alone could see them.

Galileo was also not the first ever to aim a telescope skyward, but what made Galileo unique was that he built one to study the heavens for the first time systematically and scientifically. And what he found among the stars was enough to rock the world and overturn long-held concepts of the universe.

One of his great celestial observations was that the moon had craters and mountains; of course, others had found this earlier, but Galileo used the shadows these features cast onto the lunar surface to calculate their heights and depths.

When he aimed his telescope toward the planet Jupiter, he found something even stranger. There he discovered that this distant world played host to four moons and that these swung around the planet from night to night.

Both of these are phenomena that we also can see with a small telescope. Jupiter will continue to shine brightly in our evening sky for the next few months, and the moon returns every couple of weeks, so be sure to check them both out.

One of the other great discoveries of Galileo appears low in the southwestern sky right now shortly after sunset. There you will find the brightest of all planets - Venus — just where it's appeared for the past few months. Venus shines so brilliantly because it's a world the size of Earth that now lies relatively nearby, only about 68 million miles away. In addition, the planet is shrouded by thick white clouds that reflect into space more than two-thirds of all sunlight that falls on them.

What makes Venus so spectacular right now is exactly what confounded Galileo four centuries ago. The planet appears through a telescope not as a round disk but in a quarter phase — not unlike the moon does every few weeks. And by year's end, a telescope will show it as a thin crescent!

While this may not seem like an epic discovery in today's fast-paced, high-tech world, it was this simple observation that led Galileo to conclude that the phases of Venus could not happen if the planet were orbiting the Earth as both the great Aristotle and the Catholic Church of the time had taught. No, the only way the phases could appear as they did was if Venus instead circled the sun.

In other words, our world was not the center of the universe as had long been believed. And this ultimately helped to change forever how we view ourselves and our place in the universe.

If you don't have a telescope of your own, go online and search for an amateur astronomy club in your area. Chances are they'll be having a free "star party" sometime soon where you can view through their telescopes all the wonders of the cosmos — including the amazing planet Venus.

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

The changing phases of Venus.