[EvaH (OP)]

Stephen asks:

If the earth is getting lighter by 50,000 tonnes a year does this mean that the effect of the moon on the earth has changed? In which case, we should stop going to the moon and never even think of setting up a space station there so as not to add any weight to the moon as this would have a adverse effect on the earth. We should also never take anything away from the moon i.e mining for the same reasons

What do you think?

[Kryptid]

50,000 tons is practically nothing compared to the Earth's total mass (about 6 x 10²¹ tons).

Humans, at least in their current technological state, can barely even scratch the surface in terms of changing the mass of a planet or satellite. So that shouldn't be our initial concern when colonizing space.

[syhprum]

Perhaps we should stop using solar panel as the Sun converts 80'000 tons of its mass into energy and radiates it away each second

[evan_au]

If the earth is getting lighter by 50,000 tonnes a year

Presumably, this represents atmosphere blown away by the bit of Solar Wind that gets past the Earth's magnetic field?

But it would not include the mass of meteoric dust that hits Earth's atmosphere every year, which is thought to be of a similar magnitude...

[Halc]

If the earth is getting lighter by 50,000 tonnes a year

Presumably, this represents atmosphere blown away by the bit of Solar Wind that gets past the Earth's magnetic field?

But it would not include the mass of meteoric dust that hits Earth's atmosphere every year, which is thought to be of a similar magnitude...

Similar order of magnitude yes.  About 40 kTon/yr coming in, 90 kTon of atmosphere going out.  The 50 kT figure is an approximate net.  Earth is also losing something like 16 Tons/yr due to mass annihilation, which is pretty trivial compared to the other effects.

so as not to add any weight to the moon as this would have a adverse effect on the earth.

First, the OP has gone from worrying about Earth losing mass to the moon gaining it, which doesn't follow.
Secondly, what adverse effects (from a mass change of either body) are we talking about here? None was identified.
Third: Neither the Earth nor the moon are gaining or losing weight since both are in freefall and are thus weightless. Their mass is changing (trivially), but weight is a force required for it so sit on something.

[Petrochemicals]

How would altering the mass of the moon have an adverse effect?

[evan_au]

The Moon is receding from the Earth at a rate of several centimetres per year, as a result of tidal influences.
- This is very measurable using lasers and retro-reflectors left on the Moon by various space missions.
- This has not had any measurable impact on life on Earth over the past century (although some effects are visible in the fossil record, if you go back a hundred million years or so)

Removing 300kg of rocks from the Moon, or moving 100 tons of space habitat from Earth to Moon will not have any measurable affect on the separation of Earth and Moon.
- What adverse effects are you concerned about?

See: https://en.wikipedia.org/wiki/Tidal_acceleration#Historical_evidence

[charles1948]

Perhaps we should stop using solar panel as the Sun converts 80'000 tons of its mass into energy and radiates it away each second

Yes, the constant mass-loss from the Sun ought to cause more disturbances in stability between Earth and Moon  than minor Terrestrial/ Lunar gains or losses.

 But, is the Sun's mass-loss only 80,000 tons per second, as you say?  I seem to recall, from past reading of the subject, that it used to be considered more  like 4,000,000 tons per second.  Which seems astonishing!  Which figure is correct?

[Halc]

But, is the Sun's mass-loss only 80,000 tons per second, as you say?  I seem to recall, from past reading of the subject, that it used to be considered more  like 4,000,000 tons per second.
Which figure is correct?

The latter seems more on the spot. The figure I found was 6 million tons.  I think the 4M tons is the matter destroyed from the fusion process, and the larger figure includes solar wind and other simple expulsion of matter. Not sure what the 80K ton figure is.

[evan_au]

Quote from: syhprum on 01/12/2020 15:37:32
Perhaps we should stop using solar panel as the Sun converts 80'000 tons of its mass into energy and radiates it away each second

Yes, the constant mass-loss from the Sun ought to cause more disturbances in stability between Earth and Moon  than minor Terrestrial/ Lunar gains or losses.

It seems that you have trouble recognizing a parody, Charles....

You know that the mass of the Sun is about 300,000 times greater than the mass of the Earth?

The distance of Earth from the Sun does increase by about 5 million km every year, between 4th January and 4th July
- And it comes back again over the following 6 months.
- In contrast, losing 6 million tons per second from the Sun will have no measurable impact on the orbit of the Earth or Moon this century.
- If you look on longer timescales, the Earth's orbit is affected by the influence of Jupiter and Saturn, over periods of 10,000 years or more.
- And if you look ahead 5 billion years, to when the Sun becomes a Red Giant star, it will puff off a large fraction of its mass, which will affect Earth's orbit significantly. But long before then, Earth is likely to become a lifeless cinder.

See: https://en.wikipedia.org/wiki/Milankovitch_cycles#Orbital_eccentricity