Look up with the July 2017 sky map to navigate the stars and constellations in the night sky. On this page is both a color sky map and a black and white printable map to bring outside!
Just click here or on the image below to open the printable map—then bring outside!
The Depths of Space
For countless years, observers of the night sky perceived the heavens as an enormous upturned bowl. In one of more than 1,000 quatrains attributed to astronomer and mathematician Omar Khayyám (1048?–1131), the author wrote:
And that inverted Bowl we call The Sky,
Whereunder crawling coop’t we live and die,
Lift not thy hands to It for help—for It
Rolls impotently on as Thou or I.
In this 12th-century vision of the sky, all of us are inside the inverted bowl, looking up at its inner surface. The stars are thought to be tiny glowing lights (candles, perhaps?) af xed to the inside of the bowl. Or possibly the stars are holes in the bowl, which is illuminated from the outside by a sort of celestial light. All of the stars are thought to be the same distance from us, arrayed on the inside of the bowl.
Only recently has the true scale of the cosmos become known. In the early 1920s, the development of ever-larger telescopes allowed Edwin Hubble and other cosmologists to make observations that led to our current understanding of the size of the universe. This remains one of the most profound scienti c achievements in all of human history. We nally understand that the universe is much larger than it appears at rst glance. And we’ve learned that celestial objects lie at different distances from us.
You can conduct your own investigation of the depths of space simply by observing objects in the night sky.
The Moon (not depicted on this month’s sky map) is by far the closest bit of heavenly real estate. It’s a mere 235,000 miles away, close enough that humans have actually been able to walk on its surface.
Now turn your attention to an object that’s a lot farther away but still in our celestial backyard: Looking due south, the planet Saturn is the bright object in the lower center of the map. Saturn is currently 8.5 billion miles from Earth. The Cassini spacecraft required nearly 7 years to make the trip to Saturn. Yet compared to most other objects in the sky, Saturn is a stone’s throw away.
To the lower right of Saturn lies the orange-ish star Antares. To us, Antares appears just a bit dimmer than Saturn. It’s no surprise, then, that ancient observers assumed Antares and other stars to be no farther away than the planets. But looks can be deceiving! Antares is approximately 600 light-years away. That’s a whopping 3.5 quintillion miles—a number too large to wrap our heads around. But even Antares is relatively nearby, cosmically speaking.
From a truly dark location, you will notice what appears to be a narrow, hazy cloud rising from the southern horizon and then angling up and to the left. A clue to the true nature of this cloud is that instead of hiding the stars, it seems to lie behind them. This is the Milky Way, a portion of the galaxy in which the Sun and Earth—and you and I—are located. The Milky Way is the combined light of billions of stars, each too faint and far away to be seen individually. In the thickest part of the Milky Way, in the constellation Sagittarius, lies the center of our galaxy. It’s a staggering 26,000 light-years away (one light-year equals almost 6 trillion miles!).
The night sky is neither a at surface nor a curved bowl. It is a vast, three- dimensional volume, deeper than our imaginations.
July Sky Map
Click here or on image below to enlarge this map (PDF).
Sky map produced using Chris Marriott’s Skymap Pro
Enjoy astronomy? Check out Bob Berman’s column, “This Week’s Amazing Sky.”