How big was the sun when the earth began and how would life survive?

The sun burns off 700 billion tonnes a second so wouldn’t the sun be so huge billions of years ago when life on earth began that it would be inhospitable to life?

Over 4.5 billion years ago, the gas cloud which would become the Sun had a diameter of over 480 trillion kilometers, which is approximately 50 light years. This cloud was not dense, containing only a few thousand atoms per cubic centimeters of space. The total mass of the cloud would have been sufficient for building up several solar systems. Its temperature was that of the interstellar space, not radiating any light into the surrounding space.Later everything condensed forming the sun which we konw today.

A star like the Sun has enough fuel in its core to burn at its current brightness for approximately 9 billion years. a star that is half as massive as the Sun burns slowly enough for its fuel to last more than 20 billion years.A 10 solar mass star, a star that is 10 times more massive than the Sun, burns nearly a thousand times brighter and has only a 20 million year fuel supply.

Earth became conducive to life only because of solar radiation . the solar constant has increased since the creation of the solar system (about 4.7 billion years ago). The initial value was about 70% of what it is now. During the Carboniferous period (about 300 million years ago) it was about 2.5% less than the value today.

i think you got the answer .

Edit : spanishlady ,no place for creationism in science. earth’s atmosphere is dynamic . the cloud of gases in earth’s atmosphere and the cloud of gases which formed our solar system are different in terms of their physical and chemical properties.The forces of coalescence during the formation of galaxies was incredible and it took billions of years for the formation of stars,planets,etc. there is no scope for formation of new planetary bodies out of the gases in our atmosphere.
This is how it happened…

http://abyss.uoregon.edu/~js/images/nebular_hypothesis.gif

http://abyss.uoregon.edu/~js/ast121/lectures/lec24.html

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

http://abyss.uoregon.edu/~js/images/protoplanet_1.gif

http://www.windows.ucar.edu/tour/our_solar_system/formation.html

Edit – spanish Lady,you are raising fundamental questions…..
out of the big bang – four fundamental forces of nature formed
those forces underpin everything around us —1.Gravity is the reason stars,planets,other celestial bodies formed ; 2.Electromagnetic force ;3 and 4 — the nuclear forces –The Strong Nuclear Force and the Weak Nuclear Force.
–and don’t think earth is the only planet in the universe where life exists.There could be billions of planets like earth in the universe.Considering the vastness of the universe it is an easy assumption …. and slowly we are getting scientific evidences.so the assumption that life exists only on the earth can become a myth soon.
coming to the point why life exists only on earth in the solar system ?
1.sun like star–not too big,not too small
2.perfect place in the solar system — 3rd orbit in the solar system
3.presence of bigger planets in the solar system–like jupiter which pulls the rouge asteroids towards it and protecting earth from frequent impacts.
4.unique geomagnetic field ,gravitational power — because of earth’s unique core.
5.earth’s unique moon — which influences seasons,precession of earth.
6.position of solar system in the milkyway ….it is located at the edge of the milky way .
—Everything in our universe runs according to laws of physics.each galaxy orbit around a supermassive black hole at the centre of the galaxy.This is something related to gravitational force – so in effect everything in the galaxy is spinning around this black hole and each galaxy is made up of material that’s been thrown outwards from epicentre of the big bang and as there’s nothing to slow it down, it continues be thrust outwards, hence the reason why the galaxies are getting further and further apart.

http://www.astronomycafe.net/qadir/agalaxy.html

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

http://www.eso.org/public/news/eso0226/

The universe – How big are you?

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