As we look up at the night sky, we see familiar patterns in the stars and the friendly face of our moon.  As a species, mankind has paid very close attention to the sky, often attributing great stories and legends to what we see.  A recent discussion I had on the internet had an interesting link between what we see today and what the dinosaurs would have seen back when they ruled the world.

The familiar star constellations we see in the sky are the result of the accumulated movement through 3 dimensional space of all the stars in relation to each other. If you were to go back to dinosaur time and look up, nothing familiar would be recognizable.  For instance, the north star (polaris) would not be over the earths rotational pole, or for that fact even be in the familiar pattern of the “Little Dipper”.  The constellation Orion would be totally unrecognizable as a pattern as the various star are all moving imperceptively slow in different directions and have been doing so for ever.  This holds true for every star in the sky. The dinosaurs would have seen nothing in the star patterns as we see today.

The planets are often the brightest lights in the night sky.  They were all there slowly revolving around the sun but at a slightly different rate.  They have slowed down and moved slightly further away from the sun since then.  The dinosaurs would not have seen a really big difference there.

Unlike the planets, our moon would look really different to the dinosaurs.  It is well understood today, based on highly accurate laser measurements, that the moon is slowly getting further away from the surface of the earth. During the Mesozoic (Dinosaur times), the moon would have been modestly larger than in the sky today.  It apparently is moving away from the earth at the rate of 1.5 inches per year.  (The distance was closer by approximately 1.5 inches time 65+ million years) Just like an ice skater throwing his arms out to slow down a spin, the closer moon would have enabled the earth/moon system to spin faster when the moon was closer to the earth.  This means the day was shorter, the moon was larger (maybe 1/4 larger) in the sky.  It would have been brighter because the larger disc would reflect more light and thus a moonlit night would have been less dark.  The lunar month would have been shorter as it would sweep the sky and go through it’s phases more rapidly. Another significant effect would be that the tides of the oceans would be larger because of the gravitational effects of the closer moon.  Storms driven by the earths rotation and moons gravity would have also been significantly more intense.

These changes in things that we are used to are not obvious to us because of our limited tenancy on the planet. It is a wonderful thing that science lets us observe the world the way that it actually works (worked) and not be limited to thinking about only what we can physically see in the present. The past is a detective story.  By the way, when the earth/moon system was formed 4.4 billion years ago, the moon was probably only about 14000 miles away from the earths surface, compare this to the 238,000 miles separation today.  It would have nearly filled the sky. Awesome!

If you want to see a Chesley Bonestell painting of the moon really close to the earth way back in time, go to the website: