Jupiter, the king of the planets, will grab your attention in the southeast sky of Everett this month.
It reached its closest approach to Earth last month, something astronomers call opposition, but it’s still just about as close at 381 million miles from our back yards.
That’s close for Jupiter. Because Earth and Jupiter’s orbits are not exactly circular, Jupiter is the closest it has been to Earth since 1999.
It’s by far the largest planet in our solar system with an equatorial diameter of 88,000 miles, dwarfing our 8,000-mile-wide Earth. In fact, if Jupiter were hollow, you could fill it with more than 1,000 Earths.
You may have heard that Jupiter was hit in late July by what most astronomers believe to be an asteroid about the size of a football field.
Fortunately for me this news broke while I was with more than 100 other amateur astronomers at the Nebraska Star Party just outside Valentine, Neb.
After we heard about it, as soon as it was dark enough outside, we all had our astronomical gear aimed at Jupiter. We couldn’t see the blemish near Jupiter’s south pole right away because it was turned away from our view.
Even though it’s a huge planet, it whirls around on its axis once every 10 hours. That night we had to wait a few hours until the side of Jupiter with the black smudge rotated into view.
NASA’s Hubble telescope got a much better view than our army of telescopes, but we could still faintly see the point of impact.
The smack mark on Jupiter has now faded away but there’s still much to see on and around Jupiter.
It’s very bright in our evening skies as it rises in the southeast. Nothing else is close with the exception of our moon.
Wait until about an hour and a half after sunset to start observing it. Before that, Jupiter is still pretty low in the sky and you have to look through a lot more of Earth’s blurring atmosphere.
Jupiter is basically a huge ball of hydrogen and helium gas, much like our sun. The gas gets thicker and denser as you approach what’s believed to be the planet’s rocky core. So when that asteroid hit Jupiter in late July, it never made landfall because there is no real land.
When you get Jupiter in the eyepiece of your telescope you’ll see at least some of its horizontal parallel cloud bands. You may even see some faint color to the bands.
The clouds on Jupiter are made up mostly of ammonia and methane compounds. They swirl around at speeds over 200 miles an hour and contain eddies and storms within them. The biggest storm is the famous Red Spot, which is bigger even than Earth.
Jupiter’s atmosphere is so active because of Jupiter’s immense mass and its huge gravitational force. That gravity literally puts the squeeze on Jupiter and compresses the giant gas ball.
That compression produces a lot of internal heat that drives the energetic Jovian atmosphere.
There’s also lots of lightning on Jupiter. Because of the huge magnetic field generated by its rapid rotation, aurora are common around its poles.
When you’re viewing Jupiter, start with a lower magnification eyepiece and work your way up to a higher magnification. You will reach a point of limiting higher magnification where the image will really get too muddy.
Remember also that not all nights are the same for telescope viewing. Even if the skies are clear, high winds in the upper and lower atmosphere can diminish what you see and how much magnification you can obtain clearly. If Jupiter doesn’t come in too clear one night, try it again the next night.
Another attraction around Jupiter are its four largest moons that look like little stars in a line on either side of the planet. More on that next week.
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