Eli5: if Energy and mass are equal and transformable to one another, and if the sun is constantly projecting energy on the earth, why isn’t the earth getting heavier and constantly changing its orbit?

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Eli5: if Energy and mass are equal and transformable to one another, and if the sun is constantly projecting energy on the earth, why isn’t the earth getting heavier and constantly changing its orbit?

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It’s not like the Sun is aiming all of its “lost” energy at the Earth with something like a laser. Only a tiny, tiny, tiny, tiny, tiny fraction of the Sun’s energy is hitting the Earth……
Like, sure, the Earth’s mass does increase due to energy from the Sun but most of it is just radiated back into space. Mass is made up of a lot of energy.

The Earth is getting lighter in fact, but the effect is negligible.

Some estimates show the Earth’s mass is estimated to be losing about 50,000 tons per year, mostly due to a combination of radioactive decay and gases like Hydrogen and Helium escaping into space.

But considering the Earth has a mass of about 5.97 billion trillion metric tons that 50,000 is pretty negligible.

It’s also estimated that the extra heat trapped by Global warming is worth about 160 tons per year.

And Earth gains mass from constant bombardment of tiny asteroids and comets.

The Earth is losing energy faster than it gains it. We also radiate heat into space.

Some gases can slow this process down, known as “greenhouse gases”, and this is why the Earth is getting hotter.

Even if the Earth did get way hotter, the amount of mass increase would be negligibly small.

Last thing: making things heavier doesn’t change their orbit.

One thing people seem to miss is that although energy and mass can be converted, it’s not even, a LOT of energy equals a TINY amount of mass.

That’s why atomic weapons are so potent, a tiny amount of matter is, due to E=mC^2, converted to a massive amount of energy.

In reverse, anything less than an *extraordinary* amount of energy won’t create any significant mass.

Also, just because energy *can* be converted to mass, doesn’t mean it *will* be. Energy, really, is simply momentum, or the ability to *change* momentum, so the energy from the sun increases the momentum (and therefore, energy) of the particles of the Earth that it strikes, as heat.

This *does* result in a mass increase, but it’s so slight it’s negligible, as momentum only really affects mass significantly at speeds close to the speed of light. (This is how photons have energy despite having no mass, they get their energy from momentum)

It doesn’t literally turn into matter (although this can happen with things like particle accelerators and cosmic rays), it’s just a transfer of momentum.

And as other commenters have pointed out, the Earth is losing *FAR* more mass to natural processes than it would ever gain from the sun’s light.

Everyone else is correct, basically the amount of energy the Sun projects to Earth is not only a virtually negligible portion of the Sun’s full power, Earth is also losing energy via other processes. Plus, for the energy input to actually make the earth heavier, it would have to be blasted so thoroughly that everything and everyone is turned into a glowing ball of hot ass.

Just because energy *can* be exchanged for matter (and vice versa) doesn’t mean it always is. Photons that strike the Earth are converted into thermal energy, and Earth radiates thermal energy too. We’re losing energy and mass faster than we’re gaining it.