Could 6 inches/yr save Earth?

[BlackHoleAndromeda]

So, recently I learned that the Earth is moving away from the Sun at 6 inches per year! :shock: So if scientific study says that the Sun will swell to Earth's current orbit, won't that mean that it won't reach us?

Keep in mind, (even though you all probably already know) 1 mile= 5280ft, 1 ft=12 inches, the "end of the Earth" is in 5 billion years.

 

[3488]

That is one idea I have heard, the Earth may JUST escape being overwhelmed by the sun due to the orbit of Earth expanding as the Sun slowly loses mass.

However this is far from certain as the Earth may not recede as far as thought, as Jupiter may rob Earth of some of this forward momentum.

Even the exact size of the Red Giant Sun is uncertain, the outer layers of the sun could expand as far as Mars (I say outer layers, but they will be extremely tenuous, not far short of a good lab vacuum).

However 6" per year only translates to 473,484 miles over 5 GY, only just over twice of the current mean distance from Earth to the Moon.

I've even tried metric measurements 15.24 cm per year over 5 GY = 762,000 KM. Works out the same.

Can someone else double check my figures please.

Andrew Brown.

 

[silylene]

I must be the only one with a dirty mind when I read the thread title.

 

[SteveCNC]

I must be the only one with a dirty mind when I read the thread title.

yeah I laughed when I first read the title also

 

[EarthlingX]

I've even tried metric measurements 15.24 cm per year over 5 GY = 762,000 KM. Works out the same.

Can someone else double check my figures please.

Andrew Brown.

I did, you are fine

I would just add, that 762 000 km is only 0,0051 of AU (approximately) , which is not a lot. It is actually less than Earths sphere of influence, and doesn't make much difference.

Earth, during it's regular orbit, has a larger difference between it's closest (perihelion) and farthest (aphelion) distance to the Sun, which is around 5 000 000 km.

http://en.wikipedia.org/wiki/Earth

 

[Woggles]

So, recently I learned that the Earth is moving away from the Sun at 6 inches per year!

Now me as well! I never heard this before. I was wondering, are the other planets moving away as well and by how much? Anyone know?

 

[BlackHoleAndromeda]

I must be the only one with a dirty mind when I read the thread title.

You are hilarious :roll: . But what do you think about my question?

 

[robnissen]

The sun is SLOWLY losing mass as it converts hydrogen to helium. But when the sun leaves the main sequence stage and starts converting other elements and enters its red giant phase, it will QUICKLY lose a great deal of mass. At that time the earth will be receding MUCH faster than six inches/year. Whether that will be enough to keep earth from being engulfed by the sun is currently unknown. Although due to the presense of Jupiter and other factors, it appears that earth will just not quite escape being engulfed by the sun. But the margin of errors in those models is quite high.

 

[silylene]

I must be the only one with a dirty mind when I read the thread title.

You are hilarious :roll: . But what do you think about my question?

I also read what Andrew (3488) said above. We'll be baked, but maybe not consumed.

 

[ramparts]

3488 is right - that adds up to a miniscule amount over five billion years, and that amount is far smaller than our uncertainty on how big the red giant Sun will be anyway. It could miss Earth, it could go out to Mars, we don't know yet. That margin of error is huge compared to the Earth-Moon distance or whatever the 6 inches/year amounts to.

 

[neomaine]

The sun is SLOWLY losing mass as it converts hydrogen to helium. But when the sun leaves the main sequence stage and starts converting other elements and enters its red giant phase, it will QUICKLY lose a great deal of mass. At that time the earth will be receding MUCH faster than six inches/year. Whether that will be enough to keep earth from being engulfed by the sun is currently unknown. Although due to the presense of Jupiter and other factors, it appears that earth will just not quite escape being engulfed by the sun. But the margin of errors in those models is quite high.

Good points. But, if the Sun is losing mass which causes its gravitational pull to be less, wouldn't that affect all of the planets?

I wonder if one of those solar system calculators could accept a sun with a deprecating mass over time? Throw in our planets and see what happens. Haven't played with one of those in a while. I'm sure they've evovled over time.