Moon facts: Fun information about the Earth's moon

[Admin]

Learn how Earth’s moon formed, how its orbit affects Earth’s tides, why solar and lunar eclipses happen and the history of lunar exploration.

Moon facts: Fun information about the Earth's moon : Read more

 

[Catastrophe]

"The moon is a bit more than one-fourth (27%) the size of Earth, a much larger ratio (1:4) than any other moons to their planets."

But not if you include dwarf planets - see Pluto and Charon (nearer half).

Cat

 

[sam85geo]

Our moon seems to have a "special" attraction for our species. It actually seems a comfort to notice the moon even at different phases. It is especially spectacular when the full moon rises and perspective magnifies it's presence on the horizon. I'm heartened that the moon is "taking it's time" retreating from the Earth; otherwise, I would miss it and we all would be poorer for the absence.

 

[Helio]

But not if you include dwarf planets - see Pluto and Charon (nearer half).

Yes, but is Pluto also the moon of Charon (pronounced "karen") since their barycenter is somewhere between them?

 

[Catastrophe]

Helio, Pluto is the larger. Are there any rules about which is which?

Cat

 

[Helio]

In addition to the impact from Theia is the hypothesis that this huge impact event created two moons that formed within the resulting debris disk. They, somewhat quickly, combined but with more of a "splat" -- not that destructive. This explains a number of asymmetric features we have discovered on the Moon

 

[Helio]

Helio, Pluto is the larger. Are there any rules about which is which?

Cat

I don't think there are formal rules, but the term binary likely fits in there somewhere. I think "binary dwarf planet" might be acceptable, perhaps, since Charon is round.

 

[Catastrophe]

Helio, Is this mathematical jiggling or is there any objective (observed) evidence?

Cat

 

[Catastrophe]

I don't think there are formal rules, but the term binary likely fits in there somewhere. I think "binary dwarf planet" might be acceptable, perhaps, since Charon is round.

I am happy with that.

 

[Helio]

Helio, Is this mathematical jiggling or is there any objective (observed) evidence.

The fact of an outer barycenter, or the roundness of Charon?

 

[Catastrophe]

The fact of an outer barycenter, or the roundness of Charon?

I think I referred to #6.

 

[Helio]

I think I referred to #6.

Ok. There is a great book that came out the end of 2019 entitled, "When the Earth Had Two Moons: Cannibal Planets, Icy Giants, Dirty Comets, Dreadful Orbits, and the Origins of the Night Sky" - Asphaug.

I found so many nuggets of information in that book that I compiled them into a Word doc. [Whoever wants my notes are welcome to them via email.]

The objective evidence for a second moon is indirect and circumstantial, of course, since that other moon has been long gone. But it seems to be a reasonable, perhaps best, hypothesis to explain the more recent findings for our Moon.

 

[rod]

I note this in the article about the Moon. "The pull of the moon is also slowing the Earth's rotation, an effect known as tidal braking, which increases the length of our day by 2.3 milliseconds per century. The energy that Earth loses is picked up by the moon, increasing its distance from the Earth, which means the moon gets farther away by 1.5 inches (3.8 centimeters) annually."

My observation. This rate of expansion by the Moon from Earth works out to be about 1.2 x 10^-7 cm/s. In the BB model, H0 = 69 km/s/Mpc works out to about 2.236 x 10^-18 cm/s/cm.

Q:Which rate of expansion is most secure based upon measurements? My answer the Moon's rate

 

[Helio]

I note this in the article about the Moon. "The pull of the moon is also slowing the Earth's rotation, an effect known as tidal braking, which increases the length of our day by 2.3 milliseconds per century. The energy that Earth loses is picked up by the moon, increasing its distance from the Earth, which means the moon gets farther away by 1.5 inches (3.8 centimeters) annually."

My observation. This rate of expansion by the Moon from Earth works out to be about 1.2 x 10^-7 cm/s. In the BB model, H0 = 69 km/s/Mpc works out to about 2.236 x 10^-18 cm/s/cm.

Q:Which rate of expansion is most secure based upon measurements? My answer the Moon's rate

Yes. Laser beams from McDonald Obs. our bounced off the mirrors placed on the Moon, allowing for great accuracy.