I had a heated debate this weekend with a friend over the facts of the universe expanding. My friend stated that the Earth including the Moon is both moving closer to the sun and made a statement about how this is affected due to the large gravitationally pull that the Sun has over our planet.

My stance was that the Universe is expanding and in such the Moon and Earth are pulling away from each other and in fact due to this the Moon would be moving close to the sun due to it's orbit as the Earth itself is in fact moving away from the sun. I stated that the Earth is slowing down in it's orbit due to the tidal forces and this would slowly push the Earth away from the Sun.

I would like to put this debate to rest if possible, but I would like to back up either case with viable evidence, I did do research on the web and came up with only these site so far, which to be honest is not much.

Moon moving away from the earth?

Distance from the Earth to the Sun changing?

Expanding Universe

I would like to turn this to the creative minds on this site to see if I can get more viable information on this.

Thank you.

I know for sure that the moon is moving away from the earth. The effects of gravity in a local area have a far greater impact than an expanding force. So, the earth will keep revolving around the sun as long as there is nothing to throw it out of orbit. Another way of looking at it is that the galaxy is moving as a whole so the earth and sun will always be at the same distance since they are part of the system. I don't know if my explanations made any sense but I hope it helps.

I understand were your coming from, as the universe expands as a whole the distance from the earth and sun would stay constant unless something starts to affect this orbit. But from what I've understood is that due to the tidal forces that the moon exerts on the Earth it's actually causing our orbit to be affected in a way that is pulling us away from the Sun. This was one of the arguments that I was making during my debate with my friend that believed the opposite that the Earth is pulling into the Sun which he stated would cause our death in only a few hundred years...were he got this info...I have no idea.

Also, if the sun's mass is changing due to it's temperature dropping, at a very slow and content rate, wouldn't that also affect our orbit and slowly pull us away from its grab on us over a significant amount of time instead of pulling us towards it?

I guess I'm in a spot that I feel either we are moving towards the sun or way from it in some manner especially since our own Moon is slowing drifting away from us which I sense would cause our own orbit to be affected as well.

don't worry about that, in a billion years or so when the sun goes supernova, it will expand to pluto, so we would have to drift very far in order to survive that, but then the sun would die and we would freeze lol. proof is in the hubble photos of supernovas.

The earth is not moving towards the sun. If you are looking for a straight answer, it is that the earth is slowing moving away from the sun. If I remember correctly, it is very very small, something like .01 meters per year.

The sun does lose mass since it converts mass into energy but this is also a very small amount. It is going to take a long time to really affect earth and even then, the effects are going to be very small.

The expansion of the universe is the creation of new space everywhere at all times. This means that the larger the distance between two objects the faster they will be moving apart. The effect is completely negligable for anything below galactic cluster scales. On a solar system scale there is no way you could EVER measure the effect - i suspect that over the lifetime of our solar system it would have no perceptable effect.

For COMPLETELY unrelated reasons, when you have an object orbiting around another object that spins there are interesting tidal effects that push the orbiting object away from the central object if it is above synchronous orbit and inwards if it is inside synchronous orbit. Our moon is moving away, since it orbits in more than 24 hours. We are moving VERY VERY VERY slowly away from the sun since we orbit in a year, longer than the solar rotation time of 30 days or so (the effect goes down significantly with distance so Earth's moving away is TINY even compared to the Moon's moving away from Earth.

Phobos, the inner moon of Mars, is actually moving TOWARDS mars because it orbits in less than one Martian day.

Include in this the fact the Sun is loosing mass due nuclear reactions and mass being converted to energy (thus less mass = less gravity), and the outward pressure of the solar wind and light.

There is a thread about this in the Science and Technology section, please use the search function before making a new thread.

I apologize, I actually did use the search function before posting anything new and didn't find anything. I might have been using the search feature incorrectly if this thread already does exist, I will take better care on searching in the future.






Great information, this helps allot on the discussion I was having with my friend on this matter, this is what I was hoping to get here, thank you.