Visualizing the Reach of Humanity in Space

There are hundreds of billions of galaxies in the universe, most of them millions of light years apart from each other. Our own galaxy is the Milky Way. Of course, we’re living inside of it, so we cannot ever take a picture of it. The picture below is of another galaxy (Andromeda) that we think is similar to our own. But that’s close enough for this exercise in visualization. You can click on the pictures to enlarge them.

Milky Way 1 The Milky Way is about 100,000 light years in diameter. That means that the light takes 100,000 years to go from one edge of it to the other.  Our own sun is in a minor spiral arm, called the Orion arm, about 28,000 light years from the center of the Milky Way. That means it’s a little over halfway out from the inside. Milky Way 2 In the picture above I marked a random spot. Let’s just say that’s about 28,000 light years from the center. If you enlarge the picture, you’ll see a little circle at the end of the arrow. That’s approximately the bubble where all the stars we can see with our naked eye on Earth are located. If you go outside right now, every star you see is actually in this little red circle. That’s how far we can see. That’s the “approximately 1,000 light year bubble.” Milky Way 3 About 1930, when radio became popular, we started broadcasting. Our radio waves of Churchill speeches or Hitler diatribes started leaving the earth at that time. Since then, of course, we added Gilligan’s Island and I Love Lucy over the years, bringing us to Family Ties, Seinfeld and finally Breaking Bad. There is a bubble of radio waves that started leaving the Earth around 1930 in all directions. That bubble is now 170 light years in diameter and growing every second. That bubble represents the entire reach of technological humanity into our universe. In the above picture, I tried to put that bubble of 170 light years in perspective, and I found it’s just a tiny little dot. If you zoom in on the picture above and look at the little red dot at the end of the arrow, that’s about how far humanity’s “scream” into the world has reached, at the speed of light. It will take a while before the scream reaches any listeners anywhere – and they’d better not blink, lest they miss us entirely.