Is it possible to meet dinosaurs if you move far enough from Earth?

Answer

Someone who is now 70 million light-years from Earth, and who can see the Earth, sees that Earth indeed still in the age of the dinosaurs.

There are some problems with ‘seeing the Earth’ though:

– To distinguish two objects you need a telescope whose size increases the closer the objects are in the sky (a consequence of the wave nature of light). To distinguish the Earth from the Sun from 70 million light-years away, you need a telescope with a diameter of at least 2000 km; to distinguish dinosaurs on that Earth that are 15m long (so ten to the power of ten times smaller than the Earth-Sun distance), a telescope with a diameter of at least 2 light-years in diameter is needed…

– You cannot look at the Earth from a distance without also seeing the Sun, which is 10 billion times brighter. Even if the observer has a telescope large enough to see the Sun and Earth as two points side by side, he is still blinded by the Sun so that he cannot see the Earth. Try spotting a glowworm perched on a lighthouse lamp.

It is true that with the Hubble telescope we see objects far beyond that. But those are whole galaxies, which consist of billions of stars. Distinguishing those stars is not possible at very great distances, let alone seeing planets around them, and dinosaurs on them.

The above reasoning applies to someone who is now 70 million light-years away. If you want to go there yourself, you can only do so at a speed less than light, so you need more than 70 million years to get there. And then the Earth has also aged as many years as you have traveled. So it’s impossible to do a space journey yourself that shows us things that happened before today.