It's entirely possible that something in the immensity of space has been looking for us, but I'm not convinced we've been discovered yet. We can be reasonably sure of this because of a sometimes overlooked scientific fact; and that is the incredible distance light must travel. It's truly an amazing perspective.

Here's the question:
If intelligent life is out there, way out there, would Earth even be visible?

The answer actually is "no." This is not because we are small or hard to see; but rather because to an observer far away our planet may not yet exist(!)

Huh?

When we see light from the stars, we're actually looking back in time. When we look at our nearest star, our sun, we're not seeing how the sun looks now, but how it looked a full eight minutes ago. That's how long it takes light to travel the distance from the sun to the earth.

The really interesting concept relates to other solar systems and galaxies. If we were to turn our perspective around and place ourselves in the role of an observer from far away looking AT the earth, then that observer would also be seeing OUR past.

Now here is where it gets fascinating.

They say the Milky Way, our home galaxy, is about 100,000 light years across. If someone's out there watching us from the other end of our own galaxy, they may be seeing Earth not as it is now, but only as it was when our species, Homo Sapiens, was just distinguishing itself from our "cousins," the Neanderthals. No cities, no technology.

And that's just our own galaxy. The universe has MILLIONS of galaxies. Any observer watching from any of the other galaxies in our universe would see Earth much earlier in it's history.

So all the observations in space are true only as measurements of the past. Since the size of space is so enormous, even at the relatively fast speed of light, at 300,000 kilometers per second (186,000 miles per second), it takes a long time for light to travel across these vast distances.

Finally, then, if intelligent life were searching for us from 5 billion light years away, they would not see us at all! To them, we still don't exist. That's because our home, Earth, is calculated to be about 4.5 billion years old.

5 billion years ago, our solar system probably was just a loose collection of gases.

Learn more about this author, Renato Zane.
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