Did you see that the super bright star rises shortly after sunset at dusk in the low southeastern sky? It is not a star, but the great type of our solar system, the planet Jupiter.
The 88,000-mile planet, named after the king of the gods in Roman mythology, is not only visible all night long, it's also at the closest approach to Earth for 2018, just under 410 million miles. In fact, however, Earth and Jupiter are approaching in their respective orbits around the Sun.
A few nights ago, Jupiter achieved what astronomers call "opposition." It is so called because Jupiter and the sun are more or less connected to each other opposite ends of the sky and the earth lie between them, as you can see in the diagram. Because they are at opposite ends of our dome, the sun goes down in the west as soon as Jupiter rises in the east, and vice versa, just like a full moon. The Jupiter giant roams the sky all night long to get our attention!
You can also see that Jupiter and Earth are geometrically the smallest spaced apart. Earth and Jupiter get into the opposition position every 399 days or a little more than every 13 months. That's because the earth needs 365 days to complete the orbit of the Sun, while Jupiter takes 12 years to build its much larger solar circuit. In the year Earth orbits the Sun, Jupiter has only made it around the home star of our solar system for a twelfth time. As a result, the earth needs just over a month to be in position, where it is again between the sun and the planet king.
If you have super Eagle eyes, there are times when Jupiter looks like it has little appendages on each side of it. These are Jupiter's moons. There is no way to solve them with the naked eye, no matter how good their eyesight is, but even a few small binoculars will show up to four of Jupiter's brightest moons, which look like little stars on either side of the big planet. I will have much more on Jupiter's moons and how to compete with the Skywatch column next week.
With a small telescope, you can easily see Jupiter's moons, but you can also clearly dislodge the disk of the planet from the cloud bands and zones that graze the great type of solar system.
Jupiter is mostly just a big ball of hydrogen and helium gas, but in its outer atmosphere there is methane, ammonia, sulfur, and other gases that produce the multicolor cloud bands. Two darker cloud bands on either side of the Jupiter equator are the easiest to recognize.
Storms also circulate in Jupiter's upper atmosphere. The biggest one is the Great Red Spot and it's three times the size of our planet. This huge hurricane-like storm has been raging on Jupiter for hundreds of years. Despite its name, the Big Red Spot is not so red – more like a pale pink. Unless you have a medium to large telescope and super clear conditions, it's hard to spot it in the southern hemisphere of Jupiter. What's hard to see is that it's not always visible due to the fast rotation of Jupiter. Jupiter whirls around its axis once every 10 hours, so half the time the red spot is away from us.
One really handy website that I like to use to find the Red Spot is skyandtelescope.com/observing/transit- Jupiter's Great Red Spot on Sky and Telescope. You can find the times when the red dot will cross Jupiter. This is the time when it is found in the center of the planet, just to the south of the midpoint, embedded in the darker equatorial cloud band. Keep in mind that most telescopes will give you a reverse view, so in this case you will look slightly above the center of the Jupiter disk. Seeing this pale pink storm is definitely a challenge for the starry sky.
If you look at Jupiter through a telescope, the key word is patience. Wait until Jupiter is high above the horizon, so you do not have to see through so much of the blurry atmosphere of the Earth to see it. However, you may lose some sleep because Jupiter is not high enough for a decent telescope observation until 11pm. or so.
It is also good practice to make long continuous views through the telescope's eyepiece when looking at one of the planets. This gives your eyes the ability to adjust to the level of light within the eyepiece, and you also have a better chance of getting clearer views of Jupiter through the ever-changing clarity of the Earth's atmosphere.
Get used to King of the Planets in our night sky. Jupiter will be visible in the evening through the summer!