Where in Space Are We Headed?

See Which Way The Earth, Sun, and Milky Way Are Moving

January 29, 2019
Black Hole

The center of the Milky Way galaxy with the supermassive black hole located in the middle (26,000 light years from Earth). Image combines X-rays from Chandra X-Ray Observatory Telescope with infrared emission from the Hubble Space Telescope.

NASA

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Want to be amazed? Look skyward on the next clear night. With your own eyes, you’ll be able to see which way you, Earth, the Sun, and the entire galaxy are moving in space.

You don’t need dark country skies for this. Being in a city is okay. But you do need an open swath of sky, so get out in the open somewhere, and do this at 9 p.m.

Nothing is Stationary in Space

When we look up at the night sky, we tend to think of it as a flat surface that the stars and planets move around on. But in reality, there’s a lot more 3D “space” than meets the eye. 

  1. Of course, we all know that planet Earth orbits around the Sun. 
  2. But the Sun is not stationary. The Sun and its solar system (including Earth) reside in an arm of the Milky Way galaxy. The Sun orbits the center of our huge Milky Way galaxy in an elliptical shape.
  3. Further, our Milky Way galaxy is not stationary either! It’s also revolving. We’ll get to this in a moment … 

Now get ready for something deep. This isn’t frivolous stuff!

First, Find Saturn—And the Center of our Galaxy (A Black Hole)

Okay, it’s 9 p.m. and your task is to look around and find the brightest star in the whole sky. Facing south, you’ll find that it is low in the sky and distinctly orange. This is Mars and you’ll see that it’s not horizon-scraping low, but floats only about ¼ of the way up the southern sky. Now you’ll use Mars to find two important landmarks, or maybe we should say “skymarks.”

Keep looking to the right of Mars until you come to the first bright-ish star. This is the planet Saturn, and if you own a backyard telescope, this is the finest target in the summer sky. But right now we’re not stopping at Saturn.

Instead, we’re learning an amazing thing: If you looked way, way beyond Saturn, you’ll find the center of the Milky Way. Yep, Saturn happens to be sitting in front of the center of our galaxy. That part of the sky where Saturn is, but lying 25,000 light years in the far distance, is the supermassive black hole around which our entire galaxy revolves.

That’s right, every star you can ever see revolves around that spot. Including our own Sun.

Now Find Vega—And The Direction We’re Headed

Okay, but if we’re circling that spot every quarter billion years, it’s reasonable to wonder which direction we’re going. The answer is easy these nights.

Go back to Mars and look high, high above it. And there, very nearly straight up, is a brilliant bluish star—the famous Vega.

Just to the left of Vega, well, that’s the direction Earth and Sun are zooming at 144 miles per second as we circle the center of our galaxy.

Wow. Everyone knows that our world circles around the Sun once a year. But that’s a relatively slow odyssey at just 18 miles per second. While we’re doing that, the Sun, taking us along for the ride, is zooming 144 miles per second in this direction to the left of Vega as we circle around the galactic core which is just below (and far behind) Saturn.

So, now you’ve found Saturn and the center of our Milky Way galaxy. And you’ve found Vega and the direction that the Earth and our entire solar system is heading.  

What did that take? Two minutes? And then all of a sudden you’re the only one of your friends who knows where we’re all going.

Let’s talk more about speed in space! How slow can we go? Read more about slow spinning planets and stars—and molasses.

About This Blog

Welcome to “This Week’s Amazing Sky,” the Almanac’s hub for everything stargazing and astronomy. Bob Berman, longtime and famous astronomer for The Old Farmer’s Almanac, will help bring alive the wonders of our universe. From the beautiful stars and planets to magical auroras and eclipses, he covers everything under the Sun (and Moon)! Bob, the world’s mostly widely read astronomer, also has a new weekly podcast, Astounding Universe

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