In answer to a flurry of inquiries (ok, three), that bright light in the east is Jupiter, King of Planets. It will dominate the night sky pretty much on its own until mid summer.
Jupiter is not hard to find; it rises at sunset for the next few weeks, and then earlier each night for the rest of the summer. It is the first ‘star’ you will see at dusk.
The 5th planet from the Sun is a hydrogen-helium gas sphere 11 times the diameter of the Earth, and two and one half times more massive than all the other planets combined. Jupiter’s largest moon, Ganymede, is bigger than the planet Mercury.
Jupiter has a total of 67 moons we know of. The four largest, called the Galilean moons after their discoverer, can be seen in any telescope or even steadily-held binoculars. Galileo’s greatest claim to fame, and ultimate downfall, were both stemmed from his observations of Jupiter: his blasphemous report that moons revolved around it drew the ire of the Roman Catholic Church, netting him a sentence of house arrest for the final nine years of his life for refusing to recant. Since then, astronomers have found 63 more moons, and the Roman Inquisition has given up.
What makes Jupiter a particularly great telescopic target is that you can follow the four Galilean moons as they orbit the planet; their motion is apparent over only a few hours. Add a little magnification, and Jupiter’s famous ‘Red Spot’ and coloured bands that circle the planet pop into view. Add a little more and you can occasionally watch the shadows of its moons trace little eclipses across its ‘surface’ (decent telescope required).
Jupiter’s size also makes it a super ‘Big Brother’ to the planets between itself and the Sun, including the Earth. Its powerful gravitational field routinely deflects orbiting asteroids and comets away from the inner planets. In 1994, Comet Shoemaker-Levy 9 got a little too close, and was fragmented into a few dozen pieces by Jupiter’s enormous gravity before being swallowed up. Like a bouncer outside a bar in the rough part of the solar system, he keeps those of us inside much safer.
Galileo’s work with the Jovian system totally revolutionized physics and planetary science, but at the cost of his own freedom. Quite the sacrifice, but after your first glimpse of Jupiter in the eyepiece, you understand exactly why he would.
