Earthrise--in the Before Times

[SorellaLaBefana]

Today's APOD (Astronomy Pic Of The Day) which, being Sunday, is a reposting from a past APOD, is one of the best they've ever done. Just watching this astounding event makes hope spring up.

...Earth begins to rise. Never seen by humans before, the rise of the Earth over the limb of the Moon occurred about 55.5 years ago and surprised and amazed the crew of Apollo 8. The crew immediately scrambled to take still images of the stunning vista caused by Apollo 8's orbit around the Moon. The featured video is a modern reconstruction of the event as it would have looked were it recorded with a modern movie camera...

https://apod.nasa.gov/apod/

A truly amazing accomplishment, a truly amazing video creation.

Of course, if one were standing on the surface of the moon, the earth would never rise nor set as moon is gravitationally locked to always have the same face to the earth—thus the earth is always risen. Only from the magical perspective of a lunar orbiter is it possible for any creature to see this wonderous sight

Fortunately, all earth creatures can look to the night sky and see the rising and setting of The Moon and be calmed by this also amazing, if much more common, sight.


Moon rising over Mt Rain

[brush]

1. From that, it's easy to see why people in ancient times thought the sun revolved around the Earth...

instead of the other way around.

[SorellaLaBefana]

2. So Very True

Even now, if one just goes out and looks up at the celestial sphere, it seems Quite Clear that the universe is rotating around an immobile Earth

It was only after millenia of peoples all over the world looking at the stately and awe-inspiring movements of the night sky that it first became possible to predict many of these movements, and to then begin to explain why most of the movements *were* predictable. Comets remained a problem, and were simply ascribed to being Signs from God(s).

It is interesting to realize that when first developed the Copernican heliocentric model was less accurate in predicting planetary motions than the much older Ptolemaic geocentric model which had been adjusted for well over a thousand years using epicycles (circles within circles) to make things come out right. This is because Copernicus retained the "perfect motion" of a circle for his orbits and thus still had to use some epicycles—although fewer. Not until Kepler replaced circular orbits with the "less perfect" but actually existent elliptical orbits was this resolved.

This change only occurred almost a century after Copernicus when Kepler (who was a student of Tycho Brahe, and whose observations allowed Kepler to develop his Laws of Planetary Motion) realized that replacing circles with ellipses allowed all epicycles to be discarded.

Also interesting, is that Brahe supported neither the Copernican nor the Ptolemaic models, but had worked out his own (as best I know) compromise of a geo-heliocentric solar system.

https://media.sciencephoto.com/image/c0145205/800wm/C0145205-Epicycles_of_Moon_s_orbit,_1708.jpg
Credit ROYAL ASTRONOMICAL SOCIETY (Can't make this autoshow on DU, it's worth clicking on though!)

Epicycles of Moon's orbit. This is plate 18 from the 1708 edition of the star atlas 'Harmonica Macrocosmica' by the Dutch-German mathematician and cosmographer Andreas Cellarius (1596-1665). It shows eight epicycles for the Moon's orbit round the Earth. Epicycles were mathematical constructs used to explain geocentric orbits before heliocentric models simplified the calculations. Insets (lower right and left) show the crescent, new and full Moon. 'Harmonica Macrocosmica', first published in 1660, had 30 colour plates with Latin text. This edition was published in Amsterdam by Petrus Schenk and Gerard Valk.

https://www.sciencephoto.com/media/480551/view

[brush]

3. Moving from the perfect circle orbit model to eliptical ones was also a huge leap.

I'd say moving away from the "flat Earth" belief was the biggest leap of all.

Just googled Galileo, seems he' the father of science, knowledge, astronomy...the whole works.

[Doctoris Extincti]

4. God's Truth is that...

...we give credit to Greeks, Romans and Europeans for discoveries made long before by other cultures such as Chinese, Indian and Arabian.

The Pythagorean Theorem, for example, was known to the Babylonians about 2000 BCE and to the Indians in about 800 BCE. Pythagoras lived from ~570-495 BCE.

Iranians were questioning Ptolemy's earth-centered universe by the 11th Century.

Also fun to note is that an ancient Greek (Aristarchus, from the same city where Pythagoras was born a few centuries earlier) outlined his idea of a sun-centered solar-system (and, also the universe) in about 200BCE

[brush]

5. Thanks for all that info. It goes back so far. I'm still wondering if..

the flat earth belief was still held by some...I mean with some early maps showing sea monsters waiting for unfortunate wayfarers to venture into their domain.