Your Night Sky for July 23, 2020


Planet Saturn

Saturn reaches its opposition July 20, when it’s closest to the Sun and at its brightest. It’s visible in the SE sky just a little to the lower left of Jupiter. Saturn is famous for its impressive rings, and I can actually see them with unaided vision after I’ve been out in the dark for a while.


It’s the 6th planet out from our Sun, and the second largest after Jupiter with an equatorial diameter of 74,898 miles. Since it consists almost entirely of the lightest elements, hydrogen and helium, it’s the least dense planet in our solar system.


Saturn takes 29.46 Earth years to make one orbit around the Sun, but it rotates on its axis 10.7 hours making its days short like Jupiter. Its rapid spin causes the equator to bulge 10 percent wider, also like Jupiter. But its tilt is 26.7 percent, so it has seasonal differences as it orbits the Sun like we do.


It has a markedly eliptical orbit with a difference of about 100.7 million miles between its nearest and farthest points from the Sun. Strong winds whip through the atmosphere at speeds of 1,120 MPH. Sometimes huge storms develop with bursts of lightening. Hydrogen and helium can turn from gas to liquid. They are 99.5 percent of its atmosphere.


There are at least 62 moons with Titan its largest. Titan has a thick atmosphere, lakes of liquid methane and ethane, and perhaps icy volcanoes. Enceledus is its 6th largest moon, and has a global ocean bellow its icy crust. It’s very similar to Jupiter’s Europa, and may also contain life.


Because of Saturn’s tilt and the changes as it rotates and orbits the Sun, our view of its rings changes. They are the largest of any planet in our Solar System and are actually lumps of ice. They vary in size from tiny frozen particles, to ice boulders about the size of a car. They also contain traces of silicates and rocks, but are mostly ice, and are only a few hundred feet thick. The main system is 3 rings which extend from 46,390 to 84,991 miles from Saturn.


Saturn is visible to the naked eye about 10 months of the year, since it only moves 12.2 degrees each year in its journey around the Sun. But it is the most spectacular planet in our solar system, and my favorite. It’s normally a quiet world but will occasionally have a storm. Because it’s so far from the Sun, it does not receive enough solar energy to sustain as lively an atmosphere as Jupiter. So go out and look at it!

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