The Moon May Play a Major Role in Maintaining Earth's Magnetic Field

It seems to me that the lack of one large moon is why Mars lost it's active magnetic field. The 2 smaller moons could not keep the system going. When the magnetic field died, the atmosphere and water burned off, probably due to solar winds?

We see ocean tides are higher on full moon day and new moon day- when bot the sun and the moon are on same or opposite sides of the earth. Obviously same effect ,may be applicable to molten liquid inside the earth's crust.Note the moon also rotates in the same plain as revolution of the earth round the sun. I do not know details of the rotation of smaller moons round the mars. That might explain why moons of the Mars may have less impact on Mars(if its crust also has/had liquid iron).

Does liquid iron always mean powerful magnetic fields? Doe sit happen around molten iron inside furnaces? I wish someone can tell me.

That's kind of a good news / bad news story. The Moon has been extremely beneficial to maintaining life on Earth, but that also means that life elsewhere in the galaxy is less a bit likely. Any other planet that could potentially harbor life would need a similar protective moon like the Earth's. But astronomers have noted that the moon is fantastically unique in size compared to its primary (Earth). A life bearing planet would not only have to meet a number of criteria to be as hospitable to life as the Earth is, but for life to evolve to produce intelligence it would also need a moon comparable to the Earth's moon. So the odds just got a bit slimmer.

Only if you believe that life like ours is the only life that can exist in the universe. Certainly life not like our own will be harder to detect but that is a different probability calculation.

I agree, our view of life is probably limited by the life that we are familiar with on our planet. One thing that life does is adapt to its environment. Even on earth, there is life that lives in what we consider hostile environments such as thermal vents.

On a planet without a magnetic field, perhaps the "DNA", or whatever the analog is there, would be "radiation hardened", adapted to a more robust repair or a higher redundancy.

?

The odds of life 'like ours' get a bit slimmer for the reasons I suggested.

And since Earth-type life is part of the set of 'all possible life', that means that the odds of all life got a bit slimmer. The logic doesn't require any assumptions about what 'form' life takes.

Perhaps you are trying to suggest that other forms of life become more likely if 'our' form becomes less likely.

A year or so ago I saw a science program that claimed our core was still liquid due to the extra energy from us taking a HUGE asteroid hit millions of years ago. That hit was also credited with breaking off the material that became the moon.

The hit receiving some credit for us still having a liquid core is really just a time shifter. By itself it helps explain why mars lost its atmosphere long before us but by itself it does not do much to the chance of life.

The hit causing a moon that (according to the show) is too big to be that close does seem to be an event that increases the chance of life on a planet. The tidal forces keep the core liquid longer and therefore there is a wider time window where the planet has an atmosphere.

Why is the moon not rotating on its axis?

Probably not. It's because if it does, moons dynamics in space will consequently comes to a stop sooner or later. It means a drag force on the moon, so its inertia will certainly not be conserved and someday the moon collides with Earth and it's horrible to imagine.

But, do you agree on this?

The moon is getting further away, by about 20mm per year if I remember the figure correctly. I believe it's been measured using lasers and a reflector left on the moon.

Whew! Smalls had me worried there for a second, at least the moon appears about 20mm smaller (in subtended angle) than last year, according to my
"rulerview" slide range finder. LOL