All About the Milky Way

One thing that makes Nevada’s starry skies so special is how clearly we can see the Milky Way from most parts of our state! Different cultures have seen our galaxy as a starry river, a trail of straw, and more. But what do you see when you look up? And what do scientists see today?

What is the Milky Way? Humans have seen many different things in our galaxy. Chinese tradition identifies the Milky Way as a heavenly river. In the story of the Cowherd and the Weaving Girl, the two lovers, identified with the stars Altair and Vega, were separated by the Queen of Heaven by being placed on opposite sides of the Milky Way. Once a year, a flock of magpies form a bridge, allowing the couple to briefly reunite. The Quechua people of the Peruvian Andes also see a celestial river, identifying the dark spots amidst the stars with drinking animals, including a bird, a mother and baby llama, a toad, a snake, and a fox.

A panographic image of the Milky Way.

Photo by Chris Cutshaw

One of the Armenian names of the milky way translates to ‘the way of the straw thief.’ According to legend, the warrior god Vahagn stole straw and carried it to the people to light fires and keep themselves from freezing. The straw he dropped formed the Milky Way. We get our name ‘Milky Way’ from a Greek myth. The goddess Hera, wife of Zeus, could confer immortality through her breast milk. To protect his half-mortal son, Heracles, Zeus brought the baby to nurse while Hera slept. On waking, Hera pushed the baby away and her milk formed the starry streak we call the Milky Way.

People have speculated about the nature of the Milky Way ever since we started looking skyward. The Persian astronomers Al-Biruni in the eleventh century and Nasir al-Din al-Tusi in the thirteenth century both suggested it was made of many small stars, but it wasn’t until Galileo turned his telescope to the heavens in 1610 that we had proof. In 1755, Emmanuel Kant hypothesized that we were seeing a huge body of orbiting stars held together by gravity, but it took almost two hundred more years for astrologers to put together enough evidence to understand the shape of our galaxy and the earth’s place inside it.

Now we understand that the Milky Way is a giant, flat disc more than 100,000 light-years in diameter. Our sun is located about halfway between the center and the outer edge. The galaxy is spiral-shaped, dominated by two arms extending from a central bar. When you look in the direction of the constellation Sagittarius, you’re staring toward the center of the galaxy. In that center is a supermassive, mostly dormant black hole called Sagittarius A*. We orbit the center of the galaxy once every 250 million years. The last time the sun was in our current position in the galaxy, mammals had yet to evolve, and humans definitely weren’t in the picture!

Our galaxy contains around 200 billion stars, and at least that many planets. There are also 100 million stellar black holes. In between the stars are clouds of gas and dust called the ‘interstellar medium.’ The dark spots you see when you look at our galaxy are areas where this dust blocks our view. The plane of our solar system is tipped about sixty degrees to the galaxy itself. If you’ve ever gone stargazing and looked at a star chart, you’ll know to look for the planets moving along the line of the ecliptic (and if you haven’t, check out these tips to get started!). Because our solar system isn’t aligned with the plane of the galaxy itself, what we see of the Milky Way and the ecliptic aren’t aligned, either. 

Our galaxy is one of many, and we have about fifty ‘close’ galactic neighbors in the Local Group. Our Milky way is the second biggest in the neighborhood, and you can see our larger neighbor the Andromeda Galaxy, with the aid of binoculars, near the Andromeda constellation. If you’d like to find even more in the night sky, the free star charts at SkyMaps have the locations of galaxies and instructions on how to best view them (binoculars or telescope). Or, you can just sit back and enjoy the spectacular view of our own galaxy the same way we’ve been doing for millennia!

Humans have always been inspired by the Milky Way. It sparks our curiosity, our creativity, and our sense of wonder at the world around us. Unfortunately, more than eighty percent of Americans live with too much light pollution to see our galaxy at night. But in most of Nevada, it’s visible overhead! So get out there and find your inspiration. Do you see beauty in the bright spots, or look for shapes in the shadows? Are you awed by the vast distances and galactic structure? Whatever you love, you can share it with others with the new Save Starry Skies plate! Let’s work together to keep our skies dark and our stars bright, so we don’t lose this essential part of our shared human experience forever. 

A map showing light pollution in North America with Nevada highlighted.

Also, if you’d like to learn more, these books tell the story of our galaxy in two very different ways, but both are great reads!

The Milky Way: An Autobiography of Our Galaxy, by Moiya McTier

The Milky Way: An Insider’s Guide, by William H. Waller