Thursday, September 30, 2010
Suspended over the fir trees out my door on summer evenings is the star Altair. It’s the brightest in a flat diamond of stars poised at an oblique angle over the trees, making up part of the constellation Aquila.
It’s also one of the three bright stars in what’s called in recent times the Summer Triangle: Altair, Deneb and Vega. To see the triangle around 9 or 10 p.m. this time of year, look toward the top of the sky — the brightest thing you see is Vega. Sweep left, and the star not quite as bright as Vega is Deneb. Altair toward the southern horizon is the apex of the equilateral triangle.
For quite a long time, the stars in this part of the sky have been associated with birds, or so the scholars say.
The name Altair comes from a phrase in the seventh- or eighth-century Arabic name for the constellation, Al Nasr al Ta’ir, the Flying Eagle, and means roughly “the rising one.” The Babylonians and Sumerians 3,000 years or more ago probably called it the Eagle Star, as did the Greeks later on. Aquila is Latin for eagle, the constellation’s name in Roman times. The easily visible star just above Altair is Tarazed, and dimmer just below it is Alshain, both taken from an ancient Persian name for the whole asterism, Shahin tara zed, meaning in one translation “the star-striking falcon.” Anyway it’s an image of sweeping power rendered there in the stars.
Aquila still flies there summer nights above the treetops in Maine. And higher to the east is Cygnus, the Swan, an easily spotted cross of six stars. Deneb is the top of the cross and the tail (al dhanab, in Arabic) of the swan. The central star is Sadr, the breast, and the lower star of the crosspiece is Gienah, from the Arabic al janah, “the wing,” of the swan or also the Hen for Arab astronomers. The Greeks also called the constellation Cycnos, the Swan, and simply Ornis, the Bird. Whatever you name it, that kind of grace is unmistakable there, in those stars.
Near the zenith on summer nights is Vega in the constellation Lyra, the Lyre, with one of the oldest continuously used star names from Arab sources. Indigenous Arab people called Vega Al Nasr al Waqi, variously translated as “the eagle the falling one,” or “the swooping eagle (or vulture),” or also “stone eagle of the desert.” The word Vega after a millennium of use seems to derive from waqi. The Romans called the constellation the Lyre, and the bird and music imagery were synthesized by the time Galileo turned telescopes skyward around 1610. The blue beauty of Vega, like a large bird in flight or like music, or both, is a force of grace and harmony there in the stars.
For being stationary, these powerful birds reflect kaleidoscoping wheels of motion, and they are not alone. Shot from the bow of the archer Sagittarius — who is low on the horizon (behind my firs) in these parts during July and August — and flying on a trajectory that has missed the eagle and will in some mythic future just miss the swan, is the arrow, Sagitta. Its trajectory skirted Scutum, the Shield, where one of the most graceful of all star clusters dots the sky (also obscured by trees at my house), known in the 1700s as M11 and later the Wild Duck Cluster. In a small telescope it looks, if your mind rises to its level, like a distant flock of ducks scattering, or so W.H. Smyth thought in the 1800s. The feel of it, at least, mirrors the other powerful flight taking place in the summer stars.
The ancient astronomers couldn’t see the Wild Duck Cluster, having no telescopes. And the truth is, the only constellation of all those named here whose dots connect to an image anything like its name is Cygnus. Even then, what we see there literally at a glance is a cross, not a swan. But like everything else in life, the more you watch the triangle of Aquila, Deneb and Vega, the more there meets the eye. A lot more.
Even though they’re fixed, these stars are in a special kind of flight relative to the season and the pointed firs. It’s not just that they’re enormous nuclear furnaces — so are the stars of Orion and the Big Dipper. These are revealing some cosmic motion peculiar to them that inspires a peculiar kind of awe. The awe you feel is your detection of that motion. An underlying motion, like powerful birds on the wing at night.