Why is the Earth moving away from the sun?

New Scientist ^ | Monday, June 1, 2009 | Kelly Beatty, Sky and Telescope

[SunkenCiv]

Skywatchers have been trying to gauge the sun-Earth distance for thousands of years. In the third century BC, Aristarchus of Samos, notable as the first to argue for a heliocentric solar system, estimated the sun to be 20 times farther away than the moon. It wasn't his best work, as the real factor is more like 400. By the late 20th century, astronomers had a much better grip on this fundamental cosmic metric -- what came to be called the astronomical unit. In fact, thanks to radar beams pinging off various solar-system bodies and to tracking of interplanetary spacecraft, the sun-Earth distance has been pegged with remarkable accuracy. The current value stands at 149,597,870.696 kilometres. Having such a precise yardstick allowed Russian dynamicists Gregoriy A. Krasinsky and Victor A. Brumberg to calculate, in 2004, that the sun and Earth are gradually moving apart. It's not much -- just 15 cm per year -- but since that's 100 times greater than the measurement error, something must really be pushing Earth outward... Takaho Miura of Hirosaki University in Japan and three colleagues... argue that the sun and Earth are literally pushing each other away due to their tidal interaction. It's the same process that's gradually driving the moon's orbit outward: Tides raised by the moon in our oceans are gradually transferring Earth's rotational energy to lunar motion. As a consequence, each year the moon's orbit expands by about 4 cm and Earth's rotation slows by 0.000017 second... the distance between the Earth and sun is growing because the sun is losing its angular momentum.

[SunkenCiv]

Yeah, good guess. Geez, tidal transfer of momentum has been going on since orbit started. :') Bodies in prograde motion around the parent body also slow on their axis, because they are transferring momentum to the parent body, but the parent body is (obviously) larger and the satellites move out. Bodies in retrograde gradually migrate inward and kerplunk.

[SunkenCiv]

The Moon stopped turning on its axis because it has been transferring momentum to the Earth and is a mere 1 per cent of Earth's mass. Meanwhile the two bodies have been moving away from one another as a consequence of this momentum transfer.

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[stboz]

Anybody able to calculate the inverse-square loss of insolation due to the movement away from the Sun?

Global cooling is comin' for ya!

[SunkenCiv]

This is pertinent to the list, because there are jumbo planets orbiting their stars at distances less than that of Mercury. Unless they are recent captures, they must have been burped out of their parent stars at some point in the past.

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[NonValueAdded]

Sounds like that Global Warming thing would come in pretty handy in a millennium or two.

[SunkenCiv]

Sometime in the past ten years, some joker seriously proposed using rerouted asteroids to slowly pull the Earth away from the Sun, to get ready for the day (a long long while from now) when the Sun expands and destroys everything up to our current orbit (and then some). :’)

[Red_Devil 232]

Well when you have something in the center, that every thing in a system is revolving around, and that something is burning and spewing its mass consistently into space I would guess it loses a little mass. Consequences.

[muir_redwoods]

As the sun shines, it is losing mass by the conversion of hydrogen to helium and the resultant radiation of energy which is equal to some amount of mass according to the most well know formula in history.

As the sun loses mass it seems reasonable that a body orbiting it would move in a larger orbit.

But what do I know?

[cripplecreek]

The loss of solar mass was my first guess as well.

[ETL]

I wonder if coronal mass ejections (CMEs) effect the movement of the Sun at all? Newton’s Law: for every action there is an equal and opposite reaction.

[cripplecreek]

According to last night’s thread, the atmosphere of the earth will be mostly gone by the time the sun goes all red giant on us anyway.

[mikrofon]

So in approx. 5 Billion years when the Sun expands as a red giant, we’ll be about 100,000 miles further away from it — probably still close enough to get roasted...

[listenhillary]

What will the do when the galaxy collapses in on itself and goes supernova?

[mikrofon]

(Red) Giant minds think alike ;)

[JoeProBono]

[TheBattman]

How long until the “experts” begin claiming this all is also “human-caused”... and the solution is to eliminate all Christians from the planet...

Ok - that last part was meant as a bit of sarcasm... But seriously - humans WILL eventually get the blame for this. Just watch.

[ETL]

So in approx. 5 Billion years when the Sun expands as a red giant, we’ll be about 100,000 miles further away from it

But by then the Andromeda galaxy will have collided with our Milky Way! :o!

[SunkenCiv]

I’m going to the beach.

[phatus maximus]

Duh, it’s man made Global Warming and the planet is moving toward cooler space, just like warm air rushes to cool air...EVERYONE knows this is the consensus and there is no more discussion on the matter.

[cripplecreek]

Because we’ve had enough of its crap.