Hi.

How many millions of years has our sun been burning ?... All that mass reduction being consumed to radiate energy for that lenght of time, has reduced its gravitational force attraction, and keeps happening, is it?

Then, its pull is not a constant !

 

For the earth to maintain orbit on a decreasing solar gravity pull, the orbit diameter has to continuosly diminish accordingly, does it ?

Or the orbiting speed slowing, does it?

Miguel

You mean the orbit expands, not diminishes. I'm not sure the sun loses much mass by way of radiation, since it ust fuses hydrogen nuclei into helium and radiates photons which have minimal mass (if any). The sun would also be capturing matter from space, so any matter it loses would probably be balanced by this.

IIRC the sun converts about 4 kg/s of mass into energy. The sun has a mass of ~2 x 10³⁰ kg. A billion years is ~3.15 x 10¹⁶ s

The sun spits out tonnes of protons(hydrogen) and tonnes of alpha particles(helium) into space, as well as solar flares corona mass ejections, but, as the previous post said, little, of the suns mass has been lost, only during the T-tauri stage of stars, and their deaths, do they remove sinifigantly large amounts of their mass(either by the last death throes of small sun like stars by puffing their outer layers, or by the violent supernovae of more massive stars).

it will indeed become less "attractive" even as I type this, but it`s at such an insignificant level that driving a car from A to B here will have a greater effect

 

your great great great great grandchildren would more likely notice a change if you drove an 18 tonne truck from here to eternity long before they detected any change from the suns pull

You mean the orbit expands, not diminishes.

 

i may be wrong, but i think he means exactly what he said. in order for us to maintain orbit we would have to be gradually getting closer in or gradually slowing down.