Cool Eclipse Facts (One of several on this topic)

Happy New Year to everyone! I hope that 2024 will have many blessings for you.

So, we are now 3 months away from the solar eclipse!

Here’s a bit of science on solar eclipses and how they happen.

As we all know, the Moon orbits the Earth and the Earth orbits the Sun. But the Moon’s orbit around the Earth is tilted: meaning that it passes slightly above or below the Sun’s position in the sky in most months. 

(see https://moon.nasa.gov/moon-in-motion/phases-eclipses-supermoons/overview/ and https://earthsky.org/space/why-is-the-moons-orbit-tilted-collisionless-encounters/ )

Occasionally, the path of the Moon does take it across the face of the Sun. When it does, somewhere on the Earth will see a solar eclipse. A partial eclipse takes place when the Moon covers part of the Sun. Partial eclipses take place over a very wide region. You have likely seen one.

Sometimes, the Moon passes directly in front of the Sun, and you can either see a ring of sunlight surrounding the dark disc of the Moon (an annular eclipse) or the Sun completely blocked out (a total eclipse). The difference happens because the Moon's orbit around the Earth is elliptical, and the Earth's orbit around the Sun is elliptical. This means that the apparent size of the Sun and Moon (as seen from Earth) changes slightly. 

For more details on eclipse basics, see https://eclipsewise.com/solar/SEhelp/SEbasics.html (run by retired eclipse scientist Fred Espenak)

So here's the really cool fact:

The distance between the Earth and the Moon is 400 times smaller than the distance between the Earth and the Sun. But the Moon is also 400 times smaller than the Sun.

Due to this amazing coincidence, the Sun and the Moon appear about the same size in the sky! 

If the Moon's apparent size was significantly smaller than the sun, we would see annular eclipses (from the narrow main path) - meaning that we would never see the Sun's beautiful corona (its outer atmosphere)

If the Moon's apparent size was significantly bigger than the sun, then it would not only cover the sun completely, it would block all or most of the corona.

The apparent sizes of the Sun and Moon being about the same  allows people to see annular eclipses and total eclipses (if they are willing to go to the narrow path of totality or annularity)

This incredible coincedence is unmatched from any of the other planets in the solar system!