"Jupiter At Its Brightest and Closest In A Dozen Years!"
Greetings, greetings fellow star gazers. And if you've been wondering what that bright light is in the east after it gets dark out, it's the biggest planet in our solar system, 88,000 mile wide Jupiter, which this week and next is the brightest and closest it's been in a dozen years. Let me show you.
O.K., We've got our skies set up for this Saturday night October 23rd. And if you go outside right after the Sun has set and look east you'll see Jupiter rising over the horizon, so bright you may even mistake it for a UFO or an airplane landing light. The reason it's so bright is because Jupiter is not only at opposition but also close to perihelion. And I'd better explain that.
First opposition: now we all know that our Earth makes one trip around the Sun once every year. But it takes 12 years for Jupiter to make one trip around the Sun. So once every year our Earth catches up with Jupiter at a point in space where Jupiter is directly opposite the Sun from Earth. And whenever a planet is directly opposite the Sun as seen from Earth we say that that planet is at opposition, so since Jupiter is opposite the Sun this Saturday and next week, as the Sun sets in the west, Jupiter will rise in the east and will slowly climb higher and higher into the heavens until it reaches its highest point around midnight, after which it will slowly descend and set in the west just as the Sun rises in the east. You see whenever a planet is at opposition it is visible all night long.
But why is Jupiter brighter this year than it has been in a dozen years? Simple. This Saturday when it is at opposition it is also close to perihelion. Which means 'closest to the Sun' and thus closer to our Earth. You see Jupiter's orbit is like a stretched out circle, so every year when it's at opposition it is not always the same distance from the Sun and Earth. When Jupiter is at opposition when it's far from the Sun as in 1993 it's not nearly as bright. You see Jupiter is at opposition at the same time as it's closest to the Sun only once every 12 years!
And this year is that year. In fact, this weekend is it. Indeed this weekend and next week Jupiter will not only be closer and brighter than it's been in a dozen years it will also look bigger through a telescope. And even the cheapest department store telescope will show you the bands of storms that ring its equator and several of its moons. In fact, if you have real steady hands you can even see Jupiter's disc and several of its moons through a pair of binoculars.
But, you may ask, just how far away is Jupiter from our Sun and Earth this Saturday, the night of opposition? Well it will be 461 million miles away from our Sun but only 368 million miles away from our Earth, that's close! Please don't miss this. Simply go outside just after it gets dark out, look toward the east. And if you like, watch Jupiter slowly travel across the heavens all night long. But do it now because right now Jupiter is as bright as it ever gets and won't be this bright again until 2011. It's yours for the seeing if you just remember to Keep Looking Up!
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