Welcome to the Night Sky Map for August 2020! This month, we talk about the glorious Perseid Meteor Shower—one of the best of the year—and our beloved Milky Way galaxy.
Just click here or on the image below to open the printable map—then bring outside!
The Perseid Meteor Shower
Every year in August, we welcome the Perseid Meteor Shower to our skies. The Perseids are one of the best meteor showers of the year, and they reach their peak on the night of August 12–13.
Known as shooting stars, meteors appear as brief streaks of light when small space rocks called meteoroids plunge into Earth’s atmosphere. Friction with the atmosphere heats the meteoroids to the point where they burn up, each creating a bright flash that we call a meteor.
Most meteoroids are no larger than grains of sand, but occasionally pieces of a big one survive the fi ery trip through the atmosphere to reach the ground. These surviving fragments are known as meteorites.
In summary, when moving through space, a tiny rock is a meteoroid. When we see it burn up in Earth’s atmosphere, it’s a meteor. If any part of the object survives its passage through the atmosphere and reaches the ground, it’s a meteorite.
Several times a year, Earth passes through streams of cosmic debris. When this happens, we may be treated to a meteor shower in which the number of meteors jumps dramatically to anywhere from 10 to 100 meteors per hour.
In the case of the annual Perseid Meteor Shower, every August, Earth encounters debris left behind by Comet Swift-Tuttle, which was discovered in 1862. As Earth plows through the cometary debris, each little particle appears in the sky as a momentary streak of light—a meteor.
Perseid meteors can appear anywhere in the sky, so your best viewing strategy is to recline or lie on the ground and look toward the darkest and most unobstructed region of the sky. A sleeping bag or air mattress makes meteor watching a lot more comfortable.
The Milky Way Galaxy
If you watch the Perseids from a truly dark location, use the opportunity to also observe one of the night sky’s most magnificent sights—the summer Milky Way, which is the galaxy in which our Sun and all of its planets are located.
From our vantage point within the galaxy, it appears as a huge, shimmering cloud of light arching from the southern horizon to high overhead. It glows with the combined light of billions upon billions of faraway stars, each too faint for our eyes to resolve. Added together, these myriad stars produced the soft glow that we see as the Milky Way.
Sadly, the increase in light pollution over the past century has turned the Milky Way from a common sight into one that many folks have never seen. In 1994, when the Northridge earthquake knocked out power (and therefore light) to Los Angeles, emergency centers received calls from concerned citizens who reported a “giant silvery cloud” hovering over the city. Was it dangerous? Not to worry: The city dwellers were merely seeing the Milky Way for the first time in their lives!
You need a dark location to observe the Milky Way in all its glory. A typical suburban neighborhood won’t be sufficiently dark. Moonlight, security lights, and streetlights are enough to spoil the view. From a properly dark, moonless viewing site, you can see the huge, hazy band of the Milky Way and maybe even the Great Rift, a large, dark strip of cosmic dust and gas that hides part of the Milky Way and appears to divide it in two, as shown on this month’s Sky Map.
A meteor shower lasts just a night or two, but the Milky Way is on display every night of the year, and it’s especially grand in the summer. Find yourself to a really dark spot and check it out!
Click here or on map below to enlarge (PDF).
Sky map produced using Chris Marriott’s Skymap Pro
Note: How to Read the Sky Map
Our monthly sky map does not show the entire sky which would be almost impossible. Instead, the map focuses on a particular region of the sky each month where something interesting is happening. The legend on the map always tells you which direction you should facing, based on midnight viewing. For example, if the map legend says “Looking Southeast,” you should face southeast when using the map.
The map is accurate for any location at a so-called “mid northern” latitude. That includes anywhere in the 48 U.S. states, southern Canada, central and southern Europe, central Asia, and Japan. If you are located substantially north of these areas, objects on our map will appear lower in your sky, and some objects near the horizon will not be visible at all. If you are substantially south of these areas, everything on our map will appear higher in your sky.
The items labeled in green on the sky map are known as asterisms. These are distinctive star patterns that lie within constellations. When getting your bearings under the stars, it’s often easiest to spot an asterism and use it as a guide to finding the parent constellation.
The numbers along the white “Your Horizon” curve at the bottom of the map are compass points, shown on degrees. As you turn your head from side to side, you will be looking in the compass direction indicated by those numbers. The horizon line is curved in order to preserve the geometry of objects in the sky. If we made the horizon line straight, the geometry of objects in the sky would be distorted.