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Observatory Corner: King of the Planets

Photo courtesy Wikimedia Commons.
Photo courtesy Wikimedia Commons.

A poll was recently conducted of all on-campus Sci-Tech writers whose last names end with “ooten”, and in a statistical miracle, respondents unanimously selected Jupiter as one of their favorite things to see through the telescope. This is an amazingly timely result, as Jupiter will soon be coming to the evening sky. With colored bands, circling moons, and its famous great red spot, it’s one of the most fantastic sights the observatory has to offer.

Jupiter is a gas giant planet — a ball of gas rather than a solid sphere like the earth. At twice the mass of all the other planets combined, Jupiter is easily the largest planet in the solar system. In fact, Jupiter is about as large as a gas giant can be. If mass were added to Jupiter, the extra mass would increase Jupiter’s gravity, pull the gas in, and actually make the planet smaller.

Within the gas of Jupiter, strong winds blow at over 400 miles per hour. These winds are confined to wide bands of latitude and blow in opposite directions, causing the stripes across Jupiter’s surface. The differing colors of the stripes are caused by different weather patterns, with reflective clouds being pushed to the top in some bands.

Between these colored bands lies the great red spot, perhaps the most famous feature of Jupiter. The spot has been known for over 300 years and is big enough to hold several earths. Observations indicate the spot is a high-pressure system with its cloud tops higher and colder than the surrounding area.

In the 17th century, Galileo built his famous telescope and turned it to the stars. Looking at Jupiter, he saw several small moons. As he watched over successive nights, the moons changed position, orbiting Jupiter rather than the Sun. This was a strong nail in the coffin of geocentricism, the idea that absolutely everything in the heavens revolves around the Earth.

The four moons Galileo discovered — Io, Europa, Ganymede and Callisto — are now known as the Galilean moons. In total, Jupiter has over 60 moons, with more likely yet to be discovered. While Jupiter takes the Roman name of the Greek god Zeus, a number of Jupiter’s moons were named after Zeus’ many lovers.

In the observatory, Jupiter is a magnificent sight. The bright dot in the sky becomes a large disk through the telescope. The colored bands are clear, and the Great Red Spot is visible when its side of Jupiter faces us. The four Galilean moons also shine brightly alongside the planet. Jupiter is currently rising late in the evening and will be high enough to view through the telescope just before closing time, but it rises a bit earlier every day. By the end of the semester it will be visible at all hours of the evening, making for easier viewing.

To the naked eye, Jupiter is still impressive and should be easy to find. It’ll be one of the brightest things in the sky and, unlike the stars, won’t twinkle. On Thursday, Nov. 1, finding Jupiter will be even easier: Jupiter will be right above the nearly-full moon.

Calvin’s observatory (accessible via the Science Building staircase nearest to North Hall) is open to the Calvin community clear nights Monday through Thursday, with the general public also invited on Wednesday, from 7:30 p.m. or half an hour past sunset (whichever is later) until 11 p.m. Student observers will be on duty to operate the telescope and show you the sights. For the latest information, visit

Sunset times for Oct. 26 – Nov. 2: 6:42–6:33 pm

About the Author

Sam Van Kooten

Sam Van Kooten is a Chimes staff writer for the 2012-13 school year.

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