The word "galaxy" is entrenched in the popular mind—everyone’s heard of these remote star cities, but with the exception of stargazers few have ever seen one. Or so they think. One of them has been readily visible to anyone who’s ever looked up at the summer sky on a dark clear night. It’s none other than our home galaxy, the Milky Way! And the best time of the year to see and experience it is late August into September.
Our Milky Way Galaxy is a gigantic starry pinwheel measuring some 100,000 light-years in diameter and about 15,000 light-years thick at its central hub, tapering off to as little as 5,000 light-years at its very edge. We’re located about two-thirds of the way out from its center, located in the direction of the constellation Sagittarius. On summer nights we are looking into its thickest and richest regions, while in winter we’re facing the opposite direction and seeing its thin outer portions—with the result that our Galaxy is much less obvious and striking during that season. (In spring and fall, the Milky Way lies along the horizon and we look out at right angles to its long dimension into intergalactic space itself.)
To view the Galaxy, begin by setting your Scientifics Star and Planet Locator to the date and time you go outdoors—preferably on a dark (moonless) and radiantly clear night. Avoid sources of bright illumination such as porch and street lights, and give your eyes time to adjust to the night by remaining in darkness for 10 to 15 minutes. Use this time to identify the starry outlines of the brighter constellations shown on your Locator (and a red light to maintain your dark-adaptation while doing so). Note how the pale path of the Milky Way shown on the rotating chart stretches from the northeastern horizon all the way across the sky to the southern one, passing nearly overhead at this time of year. Now compare this to the real sky, noting where its rich star stream courses through Cepheus, Cygnus, Aquila, Scutum, Scorpius—and especially the Galaxy’s center in Sagittarius. Here its big, billowy starclouds are so intense that many actually mistake them for rainclouds forming!
Expanding your exploration, sweep along the entire course of the Milky Way from horizon to horizon with your Skymaster binoculars or Astroscan wide-field telescope. The Galaxy will suddenly come alive with beautifully-tinted stars, glittering clusters and misty-looking nebulosities. And if you look carefully, you’ll notice that you’re seeing layer upon layer of stars—the brighter ones being nearer to you than the fainter ones. When that happens, our home Galaxy may suddenly appear three-dimensional. It’s then that you will truly sense the full meaning of that glorious word "galaxy"!
Just a reminder before closing: the annual Perseid Meteor Shower will peak on the night of August 11th to 12th, being best seen between 11 p.m. after the Moon has set until dawn. See last August’s Sky Talk for a details on observing it.
—James Mullaney
Former assistant editor at Sky & Telescope magazine & author of nine books on stargazing.
