originally posted by: peacefulpete
I have yet to go through the whole thread, but to me, the most convincing thing is that on Earth, the moon appears the same size as the sun, for our
eclipses to happen every once in a while.
Since the moon is completely smaller, it's an optical illusion that would seem too perfect to be natural.
The moon does not always appear to be the same size of the Sun because the orbital distance between the Earth and Moon can vary (as well as the
distance between the earth and Sun). These varying distances can make the apparent size
(the size the moon appears from Earth) of the moon vary by 14% and the apparent size of the Sun vary by 3%.
This can result in the Moon sometimes looking smaller or larger than the Sun, as was the case during this eclipse in 2017 when the Moon was smaller
than the Sun (called an "annular", which means "ring-shaped", eclipse):
and this one that happened in 2012:
Also, the fact that the moon is 1/4th the size of Earth is also pretty crazy, all by itself. Its size makes it seem like a small planet
dancing with our bigger planet (Earth).
IIRC it's the biggest moon-to-planet ratio that we've ever seen (someone correct me if I'm wrong). But it's just another anomaly that seems too
extreme to be natural.
Pluto is no longer considered a major planet, but its largest moon Charon is more than half the size of Pluto.
It seems maybe that the inner planets were less likely to form moons alongside the planet as the planet was forming -- i.e., have moon form from dust
coming together around the planet as the planet itself is forming from a dust and gas ball coming together. This formation method, called
"accretion", is thought to be the traditional way most of the moons around the giant outer planets formed.
However, only two of the four inner planets have moons at all (Mercury and Venus have none), so other unique methods of moon formation might have
happened for Earth and Mars. The Moons of Mars are thought to have been captured asteroids from the asteroid belt (although accretion is another
possible way they formed), and Earth's Moon is thought to have formed from an impact event, causing Earth to have an abnormally large moon
Heck if you were an alien, and found Earth with a moon that's 1/4th its size... I'd probably consider both objects as living planets, circling
That might be true for Pluto and Charon. While Pluto tugs at Charon, Charon also tugs at Pluto, causing the barycenter of each of their orbits (the
point around each body orbits) to be a point in space. That point is closer to Pluto than it is to Charon, but both Pluto and Charon orbit around
that point, looking like they circle each other.
The Moon tugs on the Earth as well as it orbits, but the barycenter between the Earth-Moon system is a point that is still inside the Earth. So the
Moon still orbits around the Earth itself, because that barycenter is in the Earth itself. Granted, Earth may appear to wobble around that barycenter
as the Moon tugs on it, but it would not look as if the earth and Moon circle each other.
edit on 1/21/2019 by Soylent Green Is People because: (no reason given)