Prehistoric Autumn Nights

The early dinosaur, Eoraptor, under autumn stars of 230 million years ago

In its general appearance the prehistoric night sky would look similar as today, filled with countless stars, the moon's changing phases, meteor showers. But specific star positions - such as those making up today's constellations - looked very different. This is because the earth's entire solar system orbits around the center of the Milky Way.

As the earth's solar system travels around the spiral of the Milky Way galaxy (similar to how the earth travels around the sun), its relationship to stars are constantly - albeit slowly - changing.

It takes approximately 230 million years for the solar system to complete a trip around the Milky Way galaxy. This means that the dinosaurs of the Jurassic and Cretaceous periods - both less than 230 million years old - had different star patterns than we have today. We can't see the stars as Allosaurus, Triceratops or Tyrannosaurus rex did.

However, modern eyes CAN witness many of the stars that shined on earlier dinosaurs. Since the solar system, with the earth in it, takes about 230 million years to revolve around the Milky Way, today the earth is in nearly the same position, relative to the Milky Way, as when the earliest dinosaurs were evolving in the Triassic Period, 230 million years ago. 

230 million years ago the earth was populated by early theropod dinosaurs, such as Eoraptor and Herrerasaurus (both of the Late Triassic period, approximately 231.4 million years ago, Western Gondwana, in what is now the northwestern region of Argentina). As a result, it's possible that many of the same constellations that we see today were also hanging over the heads of dinosaurs in the night skies of the Late Triassic.