Western Slope Skies - Our Galactic Address

Sep 18, 2020

Credit NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

“We are here.” That is the first thing I tell people at a national park visitor center, as I point to our location on a park map. Even if they didn’t ask, hearing it always seems to be a relief.

Instinctually, we seek that comfort zone – that sense of home – whenever we enter new territory. As children, one of the first things we learn is our home address, helping us comprehend our place in the world. Today, I want to expand that comprehension into new territory – to point to our location on a map of our galaxy.

Let’s start with the familiar, with home. We live on Earth, one of eight planets in the Solar System. This system includes our home star, the Sun, and everything bound to it by gravity. We are the third-closest planet to the Sun. If you go out tonight, look for the planets Jupiter and Saturn in the south. These are fellow planets in the Solar System – neighbors in the same apartment complex.

Expanding outward on our map, the Solar System is located within an arm of our home galaxy, the Milky Way. A galaxy is a system of stars, gas, and dust. Our galaxy looks like a spiral, with a bar in the center and several arms pinwheeling outward from it. We are about 25,000 light years from the center bar, in the Orion Arm. This small arm is named for the constellation Orion, whose bright stars also reside there. Right now, look for Orion in the early hours of the morning to say hello to our neighbor up the street.

All the stars we can see with unaided eyes are somewhere within in the Milky Way, which houses more than 100 billion stars. When the sky darkens tonight, look for that fuzzy band of the Milky Way arcing overhead. You’re seeing a concentrated view of our hometown – looking out of your home’s window across the landscape…or, space-scape. With a telescope, you can even peer beyond our hometown; our galaxy is merely one of the estimated trillion galaxies in the universe.

I use this galactic map often. As a seasonal park ranger, I work at different parks every year. In that new territory, I seek my comfort zone and look to the night sky. I see the same neighbors at Devils Tower as I did at Black Canyon – the same planets, same stars, same arc of the Milky Way. My home address changes, but not really. I, and you, still live at Planet Earth, The Solar System, Orion Arm, Milky Way Galaxy.  We are here.

Western Slope Skies is produced by the Black Canyon Astronomical Society. This episode was written and recorded by Ranger Austin Tumas from Devils Tower National Monument.