Tuesday, December 1, 2020

The Joke Planet

View to the East 11:00 PM, August 26.

View to the East 11:00 PM, August 26.

By Mike P. Usher 

Tonight Uranus is rising; by 11 tonight it should be high enough to view with binoculars. The name, as it is usually pronounced, is a source of endless humor to fifth graders; in fact Isaac Asimov called Uranus the “joke planet” in one of his essays. Nowadays, its recommended pronunciation is “your-an-us” which hardly sounds much better. Historically the Ancient Greeks probably made the word sound more like “Ou-ra-nos.”

Although the Ancient Greeks had no knowledge of the planet Uranus (it’s so faint and its movement is too slow) they did provide the mythological background. The outer planets form a sort of generational sequence. Mars’ father was Jupiter, and Jupiter’s father was Saturn. Saturn’s father was named Uranus, the god of the sky and gave modern astronomers the obvious name to call the 7th planet.

Uranus is visible to the naked eye, but with a magnitude 5.74 it’s just barely visible at a dark sky site. That is the major reason the Greeks never discovered the planet – it really does not draw attention to itself. It’s easy to find in binoculars though, look for a greenish spark. You might need to look at a detailed finder chart from the internet to locate it, however. At just less than 2 billion miles from the Sun, Uranus only shows a disk in a powerful telescope.

The asteroid Vesta, mentioned last month, is still visible – this time it’s close to a star in Capricornus’ foot, providing a handy way to locate it. Once again, you will likely need your binoculars. Ceres is worthy of honorable mention, when it gets a little higher in the sky, it makes a worthy target for binoculars. However, at magnitude 7.53 you will need a finder chart from the internet to locate it. Unlike it’s rather smaller cousin Vesta, Ceres is never visible to the naked eye. This is due to the slightly darker rock it’s made of, as well as its somewhat farther distance from the Sun.

In the very obscure constellation of Piscis Austrinus (Southern Fish) our close neighbor in space Fomalhaut shines. Until very recently the star held a record of sorts – the 1st magnitude star farthest from all other 1st magnitude stars. In the last year or two the very slow drift of stars across the sky has resulted in the red giant star Antares being awarded the title. However Antares is surrounded by a number of 2nd magnitude stars and does not look out of place, while Fomalhaut is located in a very barren spot in the sky and shines in lonely splendor.

See you next time! 

Mr. Usher is President of the Everglades Astronomical Society which meets every second Tuesday at 7:00PM at the Norris Center, Cambier Park, Naples. 

 

 

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