Sky Watch: A crescent Venus at dusk

The next time you gather friends and family, ask if anyone knows who invented the telescope. You probably won't be surprised to hear the name of Galileo mentioned; this is what many believe, but it just isn't true.

The telescope most likely originated in Holland during the late 1500s, where people used it to spot approaching ships long before they became visible to the unaided eye.

So maybe it was Galileo who first aimed a telescope skyward? Nope, others had done that before as well.

What made Galileo unique was that, in 1609, he built one of these remarkable optic tubes and used it to study the heavens in a systematic and scientific way -- something no one had ever done before. And what he found among the stars was enough to rock the world and overturn long-held concepts of the universe.

This week, you can make one of Galileo's earliest discoveries for yourself. To do so, you need only to go outdoors shortly after sunset and cast your gaze toward the western sky.This coming week, go outdoors shortly after sunset and cast your gaze toward the western sky.

It's there, in the waning light of dusk, that you will find the brightest of all planets -- Venus -- not far from where it's shone for the past few months. And on the evening of April 24, the crescent moon will pass by this planet on its way around the Earth and will create a beautiful sight.

Venus is a world roughly the size of our own, shrouded by thick white clouds that reflect back into space two-thirds of all sunlight that fall on them. And this coming week Venus appears even brighter than normal because it now lies relatively nearby, "only" some 45 million miles away from us.

This means that it stands between the sun and the Earth and is lit by sunlight mostly from behind, producing quite a startling sight.Aim a small telescope toward Venus this week and you'll discover, as Galileo did four centuries ago, that the planet appears as a crescent -- not unlike the moon. While seeing a crescent Venus 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 this planet could not possibly be orbiting the Earth as both the ancient Greek philosopher Aristotle and the Catholic Church of the time had taught, but instead had to circle the sun.

In other words, our world could not be the center of the universe, as had long been believed. And, while this announcement got Galileo in serious trouble with the Church, it helped to change forever how we view our place in the universe.

If you don't have a telescope, go online to find an amateur astronomy club in your community (www.astronomyclubs.com). Chances are they will be hosting a free "star party" in the next few weeks where you can view this sight through large telescopes, and then hang around to visit other wonders of the cosmos.