Thursday, October 1, 2020

Polaris hangs low in the North

Northern view 9 p.m., September 10. Submitted

Northern view 9 p.m., September 10. Submitted

One of the great things about stargazing is how little equipment you actually need – just a pair of eyes and a lawn chair. The more serious stargazer may wish to acquire a pair of binoculars; almost any pair will do, 7×50 perhaps being the most common. One thing you don’t need right away is a telescope. If the urge to buy one comes over you, resist it with all your might! A proper telescope is a major investment of your time and money and cannot be found in department stores. A cheap department store telescope might show decent views of the Moon and perhaps the rings of Saturn but very little else. You will be better off sinking the money you were going to spend on the telescope into a pair of binoculars.

The first thing we will do is find Polaris, the North Star. If you have seen it before, you may be surprised to see how much lower in the sky it appears here in southwest Florida. Look due north, 26 degrees above the horizon. (Your fist extended at arm’s length covers roughly ten degrees.) It can be difficult to find in the city lights sometimes—it is not the brightest star in the sky. Look for the Big Dipper off to the left (the brightest seven stars of the constellation Ursa Major); the two lowest of its stars, at the end of the bowl, are known as “the pointers.” They always point almost exactly towards Polaris.

Notice how low the Big Dipper is to the horizon. Here in Florida, it drops below the horizon by next month, not to reappear in the early evening until Spring. In the northern U.S. and Canada it can be seen all night, the entire year long. In the absence of the dipper we use the constellation Cassiopeia to locate Polaris. Cassiopeia resembles a ragged “W” roughly opposite the Big Dipper. The open end of the “W” sort of faces towards Polaris, but does not indicate it nearly as well as the pointers do. However, it’s the best we have during the winter months.

If you stare at Polaris for even an hour, you will notice that alone of all the stars in the sky it does not move. This, of course, is because Polaris is almost directly over the North Pole. All stars appear to circle around Polaris once per day. If a star does so without sinking below the horizon it is known as circumpolar. The number of circumpolar stars varies by latitude. At the North Pole all visible stars are circumpolar; at the equator none are.

That’s it for this month, now that we have our fixed reference point in the sky, we will look around next time for some more interesting views.

Mike Usher is Vice President of the Everglades Astronomical Society. The society meets every second Tuesday at 7 p.m. at the Norris Center, Cambier Park, Naples.

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