What Would Happen if the Earth Gained a Significant Amount of Mass?

I’ve pondered this question for years, and despite hours of research, I can’t find a substantial theory. I imagine such a situation is nearly impossible, but the question still lingers: What sort of consequences would occur if the Earth suddenly gained a significant amount of mass?

I’ve thought of a few ideas myself, but please feel free to prove me wrong.

  1. According to this BBC article, the Earth actually *looses * mass every year, about 50,000 tonnes annually. So perhaps if much of that original weight were gained back, we could expect to return to somewhat early Earth conditions. I certainly do not possess the intellect required to hypothesize what that might entail.

  2. The Earth’s rotation would initially slow due to a decrease in momentum. This would significantly alter climate conditions, among other things.

  3. The power of gravity would increase.

I’d love to hear other’s thoughts and ideas on this subject. Thanks in advance!

Would that not depend upon the momentum of the absorbed mass?

If the Earth gained sufficient mass, the moon might start spiralling in, with predictable consequences - in a million years or ten.

If the significant amount of mass came in the form of a large chunk of mass flying through space that hits the Earth, the effects would be devastating for life here…

No the Moon would not start spiraling in. There’s no such thing as a spiral orbit. The Moon’s orbit would become more elliptical, with the apogee at the Moon’s current position, and the perigee at some lower point depending on how much the Earth’s gravity increased.

That’s not correct. The Moon is currently spiralling out, at 3.8 cm per year. Its orbit increases as the Earth’s rotation slows. In 600M years it will be sufficiently far away that eclipses are no longer possible. Triton is currently spiralling in. As are Mars’ moons. Phobos impacts in < 50M years; Triton in ~3.6 billion years.


Kepler’s Laws of Planetary Motion seem to not mention mass at all … except that since M[sub]sun[/sub] >> m[sub]Earth[/sub], the Earth’s mass can be safely ignored.

I may not be reading that correctly though …

According to The Master, the Earth does NOT lose mass, it gains mass.

I imagine if Earth gains enough mass, it will be a real bitch to find pants.

The moon would probably leave us for a younger planet.

This can’t really be right. The angular size of the moon will become small enough that total eclipses no longer are visible from Earth’s surface, but partial and annular eclipses will still happen.

Is this about the National Geographics? I read an article once that postulated that since no one ever threw out their National Geographics, the buildup of mass would eventually squeeze the earth down below its Schwarzschild Radius, creating a black hole. Just one more thing that the internet has saved us from.

That BBC article has a medical microbiologist running the calculations as to earth’s changing mass. Just saying.

If the Earth has to go on blood pressure meds, I’m outta here!

Randall Munroe (creator of xkcd) addresses a similar scenario in one of his What-if columns… Expanding Earth.

He posits the mean radius of the earth expanding (while maintaining current density) at 1cm per second. I suppose if you just increased density and mass without the expansion you’d get similar. (Wouldn’t the gravitational effects be the same?)

The interesting effect to me was the fact that as mass increased, so would air pressure until the oxygen in the atmosphere became toxic to life.

The present amount of nickel and iron in the core already releases a lot of heat caused by gravity. Heat plumes give rise to volcanism and other tectonic activity at the surface. Any more iron and nickel and the surface might remain molten.