Get away from blue light to see the Pleiades

Saturday, Nov 10, 2018 5:04 AM

Greetings, Stargazers.

Last weekend was another day rolling the clocks back and another chance for me to complain about it. And a reminder for me to wish for some wonderful time in the future without daylight saving time. Sigh.

While I am complaining, I will also bring up the color of some of the newer LED outdoor lights. My concern is that the newer lights emit more blue light than the previously prevalent sodium street lights. And because the LED lights are cheaper to operate, there is the temptation to install them in “extra” locations that would not have been thought worthwhile last century. Or to install much brighter ones than are needed. I especially dislike the very intense pinpoints of light that can so easily ruin your night vision.

The International Dark Sky Association continues to urge the responsible use of LED lights, especially at night. The group points out that historically, whenever lighting technology has become cheaper, more lights were installed for outside use.

Blue-rich light directly contributes to more atmospheric scattering. If you are out in the county, you can look back and see the small dome of light in the sky over Durango, and the much larger dome over Farmington. Generally, the bigger the city, the bigger the associated light dome. And now, the overall blueness of the light emitted will directly contribute to the size of these light domes and decrease the number of stars that can be seen.

And blue light has been shown to have adverse health effects for both humans and wildlife.

That’s enough ranting for a while – there are lots of things to see on a clear autumn night.

The Pleiades, or Seven Sisters, and also identified as M45, can now be seen in the eastern sky after sunset. This open cluster is a prelude to the bright winter sky constellations that will be rising later in the evening. You should get your binoculars out to look at this cluster, since it is one of the objects with the biggest improvement with only a little magnification.

The stars in the Pleiades can all be considered young adult stars. They are all fusing hydrogen in their cores, and their size distribution ranges from massive, luminous, hot blue stars, to much smaller and cooler red dwarfs. With your naked eye, you can see only the bright blue ones. The white and yellow sun-like stars show up in binoculars, and the dim red ones won’t show up until you have a really big telescope or a long exposure photograph.

The Pleiades are one of the closer open clusters to Earth, but interestingly, that distance is still being actively researched because different measuring tools yield slightly different results. All distance measurements are in the ballpark of 130 parsecs, or about 420 light years.

This month

Recent months have been very good for planet watching, but that season is ending. Mars is still the brightest thing in the southern sky, but this might be the last month until next summer to get a good view of Saturn, as it heads behind the sun. On Saturday night, Saturn is a bit above and to the left of the crescent moon. Jupiter is already hidden in the sun’s glare. You might see Mercury only a couple of degrees above Antares in the evening dusk sky, but look quick, as it will set shortly after 6 p.m.

Venus is now the morning star and will be getting higher in the eastern sky as November progresses. On the few evenings around Nov. 16, Venus will be very close to the star Spica.

November is the month for the Leonid meteor shower. It is only predicted to be average this year. But since the Perseids last summer were a local disappointment, we can hope the Leonids will be better than expected. We will just have to wait and see. The best time to try to see them will be after midnight on the evenings of Nov. 17 and Nov. 18. If you get up to watch them before dawn, Venus will still be very close to Spica.

Charles Hakes teaches in the Physics and Engineering Department at Fort Lewis College and is the director of the Fort Lewis Observatory. Reach him at hakes_c@fortlewis.edu.