Signs in the Heavens Update

How Do Eclipses Happen? A Primer.

Revelation 12 King James Version (KJV)

12 And there appeared a great wonder in heaven; a woman clothed with the sun, and the moon under her feet, and upon her head a crown of twelve stars:

And she being with child cried, travailing in birth, and pained to be delivered.

And there appeared another wonder in heaven; and behold a great red dragon, having seven heads and ten horns, and seven crowns upon his heads.

4 And his tail drew the third part of the stars of heaven, and did cast them to the earth: and the dragon stood before the woman which was ready to be delivered, for to devour her child as soon as it was born.

5 And she brought forth a man child, who was to rule all nations with a rod of iron: and her child was caught up unto God, and to his throne.

Revelation 15

And I saw another sign in heaven, great and marvellous, seven angels having the seven last plagues; for in them is filled up the wrath of God. And I saw as it were a sea of glass mingled with fire: and them that had gotten the victory over the beast, and over his image, and over his mark, and over the number of his name, stand on the sea of glass, having the harps of God. And they sing the song of Moses the servant of God, and the song of the Lamb, saying, Great and marvellous are thy works, Lord God Almighty; just and true are thy ways, thou King of saints. …

Genesis 1:14

And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years:

Daniel 6:27

He delivereth and rescueth, and he worketh signs and wonders in heaven and in earth, who hath delivered Daniel from the power of the lions.

Luke 21:11

And great earthquakes shall be in divers places, and famines, and pestilences; and fearful sights and great signs shall there be from heaven.

Acts 2:19

And I will shew wonders in heaven above, and signs in the earth beneath; blood, and fire, and vapour of smoke:

How Do Eclipses Happen? A Primer.

By: Kelly Beatty | December 26, 2018. Sky and Telescope.

A solar eclipse, such as the one in August 2017, occurs only at new Moon, when the lunar disk passes directly between us and the Sun and the Moon’s shadow falls somewhere on Earth’s surface.

Conversely, a lunar eclipse takes place during full Moon, when our satellite passes through Earth’s shadow.

These alignments don’t happen at every new and full Moon because the lunar orbit is tipped about 5° to Earth’s orbital plane — only occasionally do the Sun, Earth, and Moon line up exactly enough for an eclipse to occur. (The technical name for that, by the way, is syzygy.) And, as the diagram above implies, those alignments occur roughly six months apart. In 2019, for example, two eclipses occur in January, two in July, and one in late December.

Three types of lunar eclipse are possible (total, partial, and penumbral) depending on how deeply the full Moon plunges into or near the umbra, our planet’s dark, central shadow.

If it goes all the way in, we see a total lunar eclipse that’s preceded and followed by partial phases. That was the case during the widely viewed event in September 2015, which marked the conclusion of a series of four consecutive total lunar eclipses in 2014–15! Such eclipse tetrads are not common — the last one occurred during 2003–04, but the next won’t begin until 2032.

If the Moon skims part way into the umbra, as shown at right, only the partial phases occur — you’ll see part of the Moon in nearly full sunlight, and part of it steeped in the deep, red-tinged umbral shadow.

And if its disk passes just outside the umbra, it still encounters the weak penumbral shadow cast by Earth. A sharp-eyed observer will notice that one side of the full Moon’s disk looks a little dusky.

Fortunately, every lunar eclipse is observable anywhere on Earth where the Moon is above the horizon. (But there’s still an element of luck involved — after all, the sky has to be clear!)

However, solar eclipses more tightly restrict where you can see them because the Moon casts a smaller shadow than Earth does.

If the Moon completely hides the Sun, the eclipse is considered total. With its brilliant disk completely covered, the Sun’s ghostly white outer atmosphere is momentarily revealed for durations from seconds to several minutes. In November 2013, for example, planeloads of eclipse-chasers converged in a remote portion of northern Kenya to watch just 11 seconds of totality.

A completely eclipsed Sun can be viewed only from a narrow track or path on Earth’s surface that’s typically just 100 miles (160 km) wide. Outside of that path, about half of the daylit hemisphere of Earth is able to watch a partial eclipse as the Moon obscures a portion of the Sun.

Occasionally the Moon passes directly in front of the Sun but doesn’t completely cover it. When that occurs, it’s usually because the Moon is farther from Earth than its average distance. (The Moon’s orbit isn’t perfectly circular; its eccentricity is about 5%.)

This geometric circumstance is known as an annular eclipse, so-called because you can see a ring, or annulus, of sunlight surrounding the lunar disk. Annular eclipses of the Sun occur about as often as the total ones do, and an annular’s path is likewise narrow. Outside of it observers see only a partial cover-up.

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