The Fall Equinox

In the absence of rain and to our delight, “Fernwood Rain Report” contributor Eric Fitzgerald transfers his writing skills and love of astronomy into a celestial monthly feature, “Backyard Astronomer.”

As a kid growing up in the Santa Monica Mountains, I slowly learned the names of the stars and the constellations as they wheeled through the night sky. The strange names from far-away lands in the distant human past imbued them with a mystery my young imagination couldn’t resist. Stars provided the ancients with entertainment. Our ancestors sat around campfires telling stories about the stars for hundreds of thousands of years. As such, the stars were like our first screen, the original viral video that has been deeply impressed into our shared origins.

Being able to pick out the constellations and name the stars has to be the source of lifelong enjoyment for me. Understanding—or, perhaps, only getting the faintest glimmering of —the structure of the universe never fails to fill me with the most formidable awe, but none of this knowledge was gained overnight. At first, I only learned the brightest stars and the most obvious asterisms (shapes in constellations). Now, as the years go by, it becomes easier to fill in the fainter stars and the lesser-known constellations.

From dusk to dawn we can see the stars facing the night side of the Earth as she rotates every day. As the Earth orbits the sun during the course of a year, different constellations slowly come into view. At sunset the stars rising in the east are thought to be that season’s lineup of constellations. The stars setting in the west are like the recap from the last’s season’s stories.

By staying up well past midnight (a surefire and unassailable excuse to ward off bedtime as a kid), the stargazer is rewarded with the coming attractions of next season’s stars.

Autumn is perhaps the best time of the year to observe the stars. The skies are often clear and the nights are usually mild. The days aren’t so long as they were in the summer when end of evening twilight comes so late. Stargazing is best done on clear, still, moonless nights.

When I look at my astronomy logs over the years I usually see many more entries in the fall.

Many people seem to think that an expensive telescope is required to enjoy astronomy.  While a quality instrument is nice, it is the eyes and the brain that will provide the most reward.  A simple telescope or a good pair of binoculars can enhance that reward, but the most expensive telescope in the world will not make up for a lack of knowledge and understanding. I’ve been to “star parties,” or gatherings of amateur astronomers with their telescopes positioned in favorable locations, and witnessed people with very fine telescopes who have no idea what to point them at or what they might be seeing. Sometimes, I think my favorite tool for astronomy might just be a comfortable cot or chaise lounge.

The Summer Triangle & the Northern Cross

Hopefully, I’ve persuaded you to step outside after dinner tonight and check out the sky.  Starting with the famous asterism, the Summer Triangle, it is composed of three bright stars almost overhead at sunset this time of year. Those stars are Vega, Altair, and Deneb.

To locate the Summer Triangle, find a spot with a clear view overhead. Face south by putting the last of the sunset on your right, look straight up and a little to the west (right).  Pick out the three brightest stars you see above you. The brightest star, Vega, will be the westernmost, Altair will be the southernmost, and Deneb will be the easternmost. As the weeks pass after this publication date, the Summer Triangle will slowly appear further and further west as darkness falls and the winter’s stars appear in the east.

The extremely bright, rusty-red “star” low in the south right now is actually the planet Mars. It burns with a steady light rather than a “twinkle” because the disk of Mars actually has an angular size. Stars twinkle because at such great distances, they have no discernible width, or angular size. This causes the light to get pinched out when the atmosphere is at all unsteady. Hence, the “twinkle.”

Vega is in the constellation of Lyra, the Harp. It is bluish-white in color. At a distance of 25 light years, it is our close neighbor in the Milky Way galaxy and is the fifth-brightest star in the entire night sky. That includes the stars of the southern hemisphere that are never visible here.

To the south is Altair, the brightest star in the constellation of Aquila, the Eagle. Altair was named by the Arabs of ancient Babylon. In fact, all three stars in the Summer Triangle are derived from ancient Arabic words. Altair is even closer than Vega at a distance of 16.7 light years.

Last, we come to Deneb, the brightest star in Cygnus, the Swan. Deneb is part of an asterism called the Northern Cross and is at the top of the cross. Three stars to the south make the crossbar and the fainter, southernmost star, Albireo, marks the foot of the cross. If you have a small telescope, try training it on Albireo. Even a modest magnification will reveal Albireo to be a beautiful double star. The striking color contrast of the brighter yellow-orange star with the fainter blue star makes it one of my favorite double stars. The swan in Cygnus can be seen by locating the “swept back” stars off the crossbar of the cross to mark the wings of the swan in flight. Albireo is the beak and Deneb is the tail.

Cygnus, the Swan depicted on a trading card from Urania’s Mirror, circa 1825.

Here in the Santa Monica Mountains light pollution can overpower the stars in the night sky. In some ways, however, this can actually help the beginner in astronomy pick out the brighter stars from what would otherwise be swamped by the staggering number of stars we see in the high desert or in the High Sierra. Sometimes, we get a rare treat here when the marine layer blankets the city but is clear above 1500 feet or so. Then the Milky Way can shine brightly when the light pollution from the flatlands is blocked out by the stratus clouds.

Cygnus, the Swan flies down the summer Milky Way and seems to split our galaxy in two as she flies to the heart of the galaxy in Sagittarius. The so-called Cygnus Rift is not actually an absence of stars, but rather a lane of obscuring intergalactic dust that blocks the light of the distant stars in the Milky Way. When the fog comes in at the beach, sometimes you can see the Cygnus Rift up in the Santa Monica Mountains.

So, take a stroll after dinner and enjoy our celestial companions in these mild autumn evenings. Take a little time to get to know their names. You might find it surprising that such a simple thing can be so rewarding.


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