In the year 1610, it was commonly believed that the Earth was the center of the Universe, that all bodies rotated around the perfect planet, placed by god with the heavens around it. Galileo Galilei dealt a major blow to this idea, by using an early telescope to improve his vision and look up at some surprising dots. These dots formed a line that went straight through the bright planet Jupiter. As Galileo looked again and again, night after night, he noticed that they not only persisted, they moved. Their motion was predictable, and Galileo realized that they were orbiting Jupiter, just...
In the last few days, we have watched the intricate dance of Venus and Jupiter in the Western sky after sunset. They have tangoed and passed by one another and the world has watched as the best conjunction of the year has come and gone. Don’t forget that even though they appear close in the sky, Venus is actually closer to the Earth than it is to Jupiter. Jupiter is hundreds of millions of kilometers further away than Venus. Today’s APOD is a beautiful shot by Letian Wang combining the proximity of the two planets with the (much further East...
No, he isn’t a zombie. He’s a long dead scientific pioneer. He discovered Saturn’s moon of Titan and was the first to suggest that Saturn’s odd ‘blob’ shape could be explained by rings around the planet. He was a pioneer of optics and developed a telescope with two lenses, more powerful than Galileos. He also characterized the motion of an ideal mathematical pendulum (with a massless cord and a length longer than its swing), and invented the pendulum clock as a method of keeping time. He had a few other contributions to astronomy, including the observation of individual stars in...
