Does the earth get closer to the sun over time?

Question

i know that there is an elliptical orbit and that its closer during different parts of the year than others, but over a long period of time do the planets spiral closer and closer to the sun and eventually become destroyed by it? I think someone told me the moon does that around the earth, or is that just satellites?

Answer 1

So far everyone has answered wrong! The distance between Earth and the sun is gradually *increasing.*

There is tidal interaction between the sun and the Earth. This slows down the rotation of the sun, and pushes the Earth farther away from the sun.  But how big of an effect is this? The yearly increase in the distance between the Earth and the sun is only about one micrometer (a millionth of a meter, or a ten thousandth of a centimeter). So this is a *very* tiny effect.

There is another effect which is also small, but somewhat bigger than the tidal effect. The sun is powered by nuclear fusion, which means the sun is continuously transforming a small part of its mass into energy. As the mass of the sun goes down, our orbit gets proportionally bigger. However, over the entire main sequence lifetime of the sun (about 10 billion years), the sun will only lose about 0.1% of its mass, which means that the Earth should move out by just ~150,000 km (small compared to the total Earth-sun distance of ~150,000,000 km). If we assume that the sun's rate of nuclear fusion today is the same as the average rate over those 10 billion years, then we're moving away from the Sun at the rate of ~1.5 cm (less than an inch) a year.

Answer 2

the planets will not eventually run into each other because, according to the laws of thermodynamics, everything is in a constant state of decay.since everything is decaying at their own rate, they will stay the same distance from each other. besides, even IF the universe WERE billions of years old, don't you think this would have already happened???

Answer 3

Yes.   The orbit decays over time.  Don't lose sleep over, though.