Friday, July 21, 2017  

Star Light, Star Bright


In the wee hours of a summer’s night, I lie stretched out on my deck, the boards still warm from the afternoon sun. As my eyes adjust to the dark, silhouettes of hickory and beech trees frame the only opening in the tree canopy over our house in which to view the night sky. On this moonless night, the Milky Way is a river of sparkling debris, and the sky is studded with thousands of stars.
I’ve come outdoors to view the annual Perseids meteor shower, August’s most splendid celestial show. At its peak, astronomers have promised 50 to 100 meteors per hour. Having lived much of my life amid urban and suburban sprawl, with myriad sources of light pollution, I’ve never witnessed a meteor shower. Suddenly, a huge ball of green and golden gasses streaks by overhead. In awe of the celestial display that continues on for hours, my eyes eventually grow heavy, the vast song of the universe singing me softly to sleep.
Growing up in San Francisco, where evening fog and winter rains obscured the stars, my first introduction to astronomy occurred during a school field trip to the world famous Morrison Planetarium with its amazing, one-of-a-kind star projector. As my eight-year-old mind tried to fathom the infinite scope of the universe and the tiny speck rotating within it called Earth, afterwards I dreamed of stars, nebulas, comets, meteors, and planets. But it wasn’t until I attended summer camp high up in the Sierra Nevada Mountains, where the air is thin and crystal clear, that I truly experienced the wonders of the night sky.
Every night the sky presents us with a free show, if we only take the time to step outside and look up. Some stars keep us company year round; others only appear a few nights a year. Constellations rise and fall, each one with its own mythological story to tell, handed down from one generation to the next through the centuries.
There are eighty-eight constellations in all and every season brings the return of familiar faces. The Big Dipper, an asterism of seven stars that help comprise the constellation Ursa Major (the Great Bear), is probably the most recognizable feature in the night sky. The Pleiades or Seven Sisters, a star cluster in the constellation Taurus the Bull, appears as a glittery smudge high overhead. In late summer, Orion the Hunter begins his march across the sky, and is one of the most conspicuous constellations seen the world over.
Throughout the year, the twelve zodiacs parade across the heavens with names we’ve known since childhood—Capricorn, Aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Scorpius, and Sagittarius. Together they form a circle of twelve 30º divisions of celestial longitude centered upon the ecliptic, the apparent path of the Sun across our celestial sphere over the course of a year. Not just daily or monthly astrological predictions, but clusters of stars that return year after year.
Until about 400 years ago, the predominant perception was that the Earth was the center of the universe and that all celestial objects orbited around it. In 1608, word spread across Europe of a Dutch invention, a tube with glass lenses that enabled viewers to see distant objects close up. Galileo obtained a telescope in 1609 and improved upon its design.
Training his improved telescope on the night sky, Galileo’s findings and hypotheses revolutionized man’s thinking about our place in the universe. For it, he was branded a heretic and spent the last nine years of his life under house arrest. Even today, in this age of the internet, deep space telescopes, and man’s footprints left upon the surface of the moon, one in five Americans still believe this geocentric model.
Yet in the past few decades, astrophysicists have made great strides in mapping the sky, using the Hubble telescope and sophisticated electronic devices, reporting there may be hundreds of billions of galaxies all around us. Scientists have determined that our own galaxy, the Milky Way, is 100,000 light-years in diameter, holds an estimated 100 billion stars, and is about ten billion years old. The entire spiral spins like a pinwheel, completing a rotation about every 200 million years.
On the clearest nights, in the darkest places, you can see as many as two thousand stars with the naked eye. Today, all one needs is a clear night, a pair of binoculars, a star map, and a rudimentary understanding of astronomy to enjoy one of the greatest shows on Earth. Many of us living on the Middle Peninsula and Northern Neck are fortunate in that we can find places of relative darkness, away from manmade sources of light pollution. That place may be as close as your own backyard.
Once hooked on the night sky, I wasn’t content with just binoculars, so one Christmas I splurged on a six-inch Newtonian reflector telescope for my husband. It was the eve of 1986 and the world’s most famous comet, Halley’s Comet, would be visible soon as it continued on its seventy-six year journey around the sun. What better excuse to buy a telescope?
While waiting for Halley to return, we trained our telescope on the moon, stunned by the close-up look of its craters and shadows cast by towering mountain peaks. We spotted Jupiter’s four Galilean moons and Saturn’s rings that have puzzled astronomers since Galileo first spotted them in 1610. We homed in on M52, an open star cluster in the constellation Cassiopeia. When Halley did appear, observers hailed it a bust. Barely visible to the naked eye, some orbits are simply better than others. It won’t appear again until 2061 but you can see bits and pieces of its debris during the annual Orionids meteor shower.
Other comets followed—Hyakutake, Hale-Bopp, Bradfield, and Levy. An amalgam of frozen chemical compounds, comets begin to warm as they approach the sun, releasing gases that form a glowing coma and a dust trail streaming behind. In March 2004, the European Space Agency launched Rosetta, ultimately placing the Philae lander on the surface of comet Churyumov-Gerasimenko, an historical first.
As comets travel through the solar system, the outer layers vaporize, emitting tons of debris in their wake. As Earth passes through these debris trails, the results can be spectacular. Since meteor showers occur with regularity, their appearance is predictable. Annual meteor showers are numerous and can vary widely in intensity, but a few storms are worth staying up late for. The Perseids occur in mid- summer and at its peak the flow of shooting stars can reach as many as eighty an hour. The Orionids peak in mid-October when summer’s haze is just a memory; followed by the Leonids in mid-November, and the Geminids in mid-December, The Quadrantids usher in the New Year; the Eta Aquarids peak in early May.
If you feel limited by your binoculars or spotting scope, you might consider investing in a telescope. Avoid the toy or big box store offerings. Their optics are of low quality, mass-produced, and will be sure to disappoint. Do your research carefully--online, at the library, one of the quality astronomy magazines, or from someone who owns one. Most amateur astronomers will be happy to share their knowledge with you.
Telescopes fall into three main types: refractors, reflectors, and catadioptric. Each type has pros and cons and selecting which type depends on what facet of star gazing interests you most. The larger your telescope’s objective lens or mirror, the more light will enter it, and more objects will be visible through your scope. Interchangeable eyepieces change the telescope’s magnification, and high quality lenses are a must. Many new telescopes come available with computerized mounts, helping skywatchers keep their favorite sights in view as they move across the sky. Computers will also help locate interesting features simply by entering in the coordinates or even the name of the object desired.
Local astronomical societies and clubs offer get-togethers where both professional and amateur stargazers can share their enthusiasm for astronomy. They offer a wealth of information, for beginners and veteran stargazers alike. GoAstronomy.com provides a list of astronomy groups throughout Virginia.
Star gazing requires you to put aside electronic gadgets, turn off the lights, and step out into the dark. As man has become increasingly dependent on manmade sources of light, our ability to embrace the dark seems preternatural. Our ancient ancestors feared the dark, yet venerated the lights of Heaven. Over the eons, stars have cast down myths and legends, portents and prophecies.
As I awake, a few vestiges of the Perseids fly by overhead. A breeze stirs the trees and the deck has cooled. If the universe is expanding as scientists say, rushing outward at speeds we can barely fathom, it’s even more impossible to imagine what that moment was like when the cosmos was born. Gravitational pull keeps most of us earthbound, forced to look up to see the stars. The light we see is from our past, not the present, traveling light years to reach us. They will always be a part of our lives; we all belong to the sky.