1 upvotes, 4 direct replies (showing 4)
View submission: Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science
Does our planet gain mass? With an almost constant energy flowing from the Sun and billions of species of flora growing every day can we say that Earth is gaining mass through its biosphere?
Comment by atomfullerene at 13/09/2023 at 15:00 UTC
10 upvotes, 1 direct replies
Growing plants don't really use sunlight to synthesize mass out of nothing, they pull mass from the air and water and use sunlight to combine it into more biomass.
Comment by SonOfOnett at 13/09/2023 at 15:28 UTC
4 upvotes, 0 direct replies
Energy-wise we also lose it to radiating heat and light. Far more of earth’s mass changes occur due to small meteors/mass falling into our orbit and some being lost due to orbital escapes, volcanic eruptions
Comment by TheFrostSerpah at 13/09/2023 at 18:49 UTC*
2 upvotes, 0 direct replies
Just a correction: The sun doesn't give Earth energy. Earth radiates into space exactly as much energy as its given by the sun. The 2nd law of thermodynamics states that in a closed system energy is preserved. Energy is neither created nor destroyed, it is transformed and "degraded" into more difficult to use forms of energy. What the earth is given by the sun is energy that is highly usable, that is, low entropy. Veritaseum has a whole video on the matter if you are interested in more info.
To answer your actual question, the Earth's mass is relatively stable. It does slowly lose some of the lighter gasses of the atmosphere as well as it radiates some particles. But what is loss is kinda compensated by stuff (mainly asteroids and such) incoming from space.
Comment by loki130 at 13/09/2023 at 18:22 UTC
1 upvotes, 0 direct replies
The mass gained by conversion of light energy to mass by photosynthesis is largely balanced out by heat radiated out when that mass is metabolized or otherwise decays--really on net the earth is losing energy as heat trapped in the interior gradually escapes. More significant is loss of atmospheric gasses like hydrogen to continuous escape off the top of the atmosphere, but this is still at far too low a rate to make much of a dent in the planet's total mass even over billions of years.