Did the night sky look the same from Earth a billion (with a b) years ago? If not, how has it changed?

Answer 1

A Billion years ago the Sol System was in a different part of the Galaxy.

There would be no recognizable constellations.

Even the location and appearance of the Magellanic Clouds would be different.

There would be more dust and gas in the Milky Way... from stars that hadn't condensed yet. There would also be some stars visible that would have burned out by our time.

We might have been closer to the Galactic Center... but I'm not sure.

Many things would be different... but there would still be stars shining brightly :)

Answer 2

No, it did not. While I don't know the specifics, a billion years (let's say a thousand million years ago, because some use the term billion differently) allows the proper motion of many stars to move them many degrees from their current positions.

The star Aldebaran, (alpha Taurii) currently is in the open cluster Hyades. However, it is not a member of that cluster, and a billion years ago would have been many degrees away. The five inner stars of the asterism the Great Bear (or the plough) are part of a close open cluster (the end of the handle and the top star of the outside of the plough or dipper are not members of that cluster) would have been in a different part of the sky, but roughly in the same configuration. Another thing..alpha Ursa Minoris possibly was not the pole star, either, but due to the axial wobbling of the earth (precession) it well could have been.

In addition, the moon was much closer...it has receded due to the mutual effects of tidal energy with the earth. Also, the day was much shorter for the same reason (this is confirmed by evidence from the growth lines of marine fossils, especially bivalves--but from those living more recently than a billion years ago). About 400 million years ago the day was about 20 hours in length, and so it was even shorter a thousand million years ago.

However, in general there were stars of various brightness in the sky, there was a milky way, there were star clusters, the moon went through it's phases, and the sun rose and set. In that respect the sky was the same. One other difference: there probably were more meteors.

Answer 3

Well, first off the sun was different, it was not as well behaved as it is now and was a slightly darker yellow/orange. There may have been additional dust in the atmosphere from more frequent asteroid or meteor impacts.

Atmospheric composition was different but definitely heading the the direction of a breathable atmosphere.

The acidity of the ocean may have been signnificantly different, depending on volcanism and other factors.

Furthermore, it's very possible that for millions of years at a clip, the Earth has sported a delicate ring of some kind or another, that would be rather spectacular to see from the surface, it could also be dangerous from the perspective of falling debris from the ring, this would fall along the axial orbit of the ring (along the surface of the planet below where the ring's orbit is). Forest fires and small impacts from meteorites would be commonplace for most all of the life of the ring.

Also, the moon would be alot closer and there would be seriously large tides.

Also, based on the solar systems's travels through the galaxy, depending on what exactly was going on at the galactic level, there could have been more stars in the sky, based on occasionaly intersecting with more dense parts of the galaxy.

We wouldn't recognize any of the star patterns but the big arc of the Milky way would probably be similar but not identical.

These more dense parts of the galaxy also tend to increase the meteor and asteroid impacts because the solar system's Oort cloud is believed to be able to be perturbed by the increased interstellar gas volume.

There could be prominent features like supernovae or other objects which have since blown out past our ability to see them.

Answer 4

We didn't have the same pole star a billion years ago. So the sky would have seemed to revolve around something besides the north star. Plus, stars would have shifted quite a bit in that time. You'd have to look up the particular velocity of every single start to get the new picture though. And there's a lot of them. Try a night sky program instead - like Voyager III.

Answer 5

The Moon would be a bit bigger, and the Sun a bit dimmer. If it's true that Saturn's rings are a temporary phenomenon, they might not be present. If they are a permanent feature, they would be noticeably more extensive. The Earth would rotate somewhat faster - ie have shorter 'days'.

Almost no star currently visible in the sky was visible then. Anyone big enough to be seen from far enough away wasn't made yet. Some dwarf galaxies would be in different positions, most visibly the Magellanic clouds but there may be a few others. Andromeda would be dimmer and most other distant galaxies a bit brighter.

Answer 6

Same answer as my million (with an M) answer, but of course the movement would be dramatic. Some stars that are very close and bright in our sky today would be far away and not even be visible while others we cannot see today would be close and bright. Otherwise, the same, lots of stars.

Answer 7

No, it didn't because the Sun was newer and the Sun hadn't given off as much heat and in the passing years the Sun has given off more heat to make more stars.