What you call the Milky Way is what folks in China call the “Celestial River” and folks in Africa call the “Backbone of the Night.” In Siberia, it’s viewed as the “Seam of the Sky,” and in India it’s considered the heavenly version of the sacred Ganges River. Whatever you call it, you can easily see it now.
All you have to do is step outside in the evening on a cloudless night when all of sunset’s glow is completely gone and face south—so that the place where the sun went down is on your right. Look for the brightest object in the southern sky: this is the planet Jupiter. (Keep in mind that because Jupiter is orbiting, it’s not always where we’re seeing it now. However, right now finding Jupiter is a good way to find the core of our galaxy.) If you stretch out your arm so your elbow is locked, you’ll see that one palm width to the right of Jupiter is something that looks like a cloud, but is actually our galaxy’s core.
You’re looking at billions of stars that are so far away you can’t make them out individually. Yet they’re so numerous that you certainly can see their light.
If you could leave your body, leave our galaxy, and look back at it from outer space, you’d see that its shape resembles a pizza pie with an orange in the center. The orange is a dense concentration of stars that are being pulled together by the powerful gravity of a black hole. This dense concentration is the “cloud” that you see to the right of Jupiter.
So long as you stay inside your body, you can’t ever see the entire galaxy, because you’re in it. In other words, you’re like a little anchovy on the pizza, located about two-thirds of the way out from the center—way out in the boonies. Part of the galaxy is on one side of you and part is on the other side. Therefore, part is above your horizon now and part is below your horizon.
Fortunately, what’s visible to the right of Jupiter is the part that’s most densely populated with stars. The part that’s located even farther out in the boonies than you are, is what you see when you turn your body so that the core is at your back. You’ll notice that the galactic plane stretches from south-southwest, across the sky to the north-northeast and it thins out as you shift your glance away from the core in the south-southwest.
So, what is located two-thirds of the way out from the galactic center? It’s our sun with its family of planets—our solar system. Our sun and its family of planets are orbiting the center of the galaxy every 225 million Earth-years. In other words, we orbit our sun 225 million times while our sun is making one orbit of the galaxy. This one orbit is called one “galactic year.”
If you’d like to see a scale model of this, just imagine that our solar system is the size of a teacup. At this scale, our galaxy is the size of North America. And it’s just one galaxy among at least 400 billion others!
Does this contrast of scale make your biggest problems seem a little less monumental?
You can visit with Harriet and email her at her Website: www.passengerplanet.com.