Did you know the path of Earth is spiral around Sun?

Quoting from the link: http://www.microvolt.com/gravitation/facts.pdf: "It is possible to calculate through complex calculations the time it would take for the planet Mercury to fall into Star (Sun). Millions of years ago planets and moons have fallen into the Sun!

I do not know where 'Microvolt Labs' gets this B.S. from, but the article has one thing right: planets and moons are on spiral paths, but it is away from the primaries, not towards them! Tidal gravity effects cause the away-spiral, where some rotational energy of both masses are transferred to orbital energy of the secondary. This drives, for instance, our moon away from Earth at about 4 cm per year.

The fascinating effect of tidal gravity is dealt with in some detail on my website.

That's interesting Jorrie. I bow to your superior knowledge, but I always understood tidal dissipation effects were reducing the satellite's orbital energy, causing it to spiral in (both kinetic and gravitational potential energy decreasing with orbit radius, according to my calcs).

I remember reading some time ago about a scenario for the end of (advanced) life on Earth being due in part to the Moon coming closer and causing tides hundreds of metres high, washing right across land masses.

Interested in the explanation. I believe the Moon's distance can now be measured using lasers to a few Angstrom units (I jest) so presumably the actual change has been confirmed.

Hi Codemaster; what you say is true if a natural satellite orbits retrograde around a planet. In pro-grade orbits like our moon, the tidal frictions drive the satellite away from us.

This is because the total angular momentum of the Earth-moon system must remain constant. Earth is losing some rotational momentum due to tidal friction and this is made up by moon getting some extra orbital energy, thus going higher. The mechanism for this orbital energy transfer is discussed in some detail on my website.

And yes, it is routinely measured with laser ranging.

Regards

Jorrie

OK Jorrie, thanks and regards

Jorrie,

I had read years ago, that the Earth's rotation is slowing infinitesimally due to increased cosmic dust of thousands of tons a year. Any validity to this?

If the 'cosmic dust' comes from random directions, Earth's rotation rate may slow down due to the extra mass, but the effect will be very, very much smaller than the other known effects.