6.5 Eclipses Text pp

An eclipse occurs when one astronomical body casts its shadow on another. An eclipse occurs when one astronomical body casts its shadow on another.

A lunar eclipse happens when the Earth’s shadow falls on the Moon. A lunar eclipse happens when the Earth’s shadow falls on the Moon. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a full moon.

A solar eclipse happens as the Moon’s shadow falls on the Earth. It occurs when the Moon passes between the Sun and the Earth, and the Moon fully or partially blocks the Sun. This can happen only during a new moon.

Rarity of Eclipses As stated before, we would have eclipses every month but for the tilt. With the tilt, the moon lies above the Earth’s orbit for half the month and below it for the other half. As stated before, we would have eclipses every month but for the tilt. With the tilt, the moon lies above the Earth’s orbit for half the month and below it for the other half.

Eclipse Seasons Twice each year the Moon’s orbital plane (if extended) passes through the Sun. These times are eclipse seasons, and eclipses will happen only then – when the Moon crosses the Earth’s orbital plane. Twice each year the Moon’s orbital plane (if extended) passes through the Sun. These times are eclipse seasons, and eclipses will happen only then – when the Moon crosses the Earth’s orbital plane.

At all other times, the shadows of the Earth and Moon always fall on empty space. At all other times, the shadows of the Earth and Moon always fall on empty space.

During eclipse seasons when a solar eclipse occurs at new moon, conditions are right for a lunar eclipse to happen at either the previous or the following full moon. During eclipse seasons when a solar eclipse occurs at new moon, conditions are right for a lunar eclipse to happen at either the previous or the following full moon.

Because the tilt of the Moon’s orbit is not exactly fixed – the Moon’s orbit precesses, swinging once around about every 18.6 years. This makes the dates of the eclipse seasons shift by about 20 days each year. Because the tilt of the Moon’s orbit is not exactly fixed – the Moon’s orbit precesses, swinging once around about every 18.6 years. This makes the dates of the eclipse seasons shift by about 20 days each year. No matter when the eclipse season falls, at least two solar eclipses must happen each year. No matter when the eclipse season falls, at least two solar eclipses must happen each year.

Because the Moon is so small compared with the Earth, its shadow is small, and therefore you can see a solar eclipse only from within a narrow band. Because the Moon is so small compared with the Earth, its shadow is small, and therefore you can see a solar eclipse only from within a narrow band.

Eclipse View from the ISS. The International Space Station was in position to view the umbral – ground – shadow cast by the moon as it moved between Earth and the sun during a solar eclipse. This astronaut image captures the umbral shadow across southern Turkey, northern Cyprus and the Mediterranean Sea. P HOTO BY NASA P HOTO BY NASA

Mankind’s fascination with eclipses has been going on a long time, since at least November 30th, 3340 BC when Irish Neolithics built an eclipse tracking cairn site and recorded the event in stone. What is this?

Appearance of Eclipses During a lunar eclipse, the Earth’s shadow gradually spreads across the Moon’s face. It takes about an hour for the Moon to be completely covered. At totality, the Moon generally appears a deep ruddy color. During a lunar eclipse, the Earth’s shadow gradually spreads across the Moon’s face. It takes about an hour for the Moon to be completely covered. At totality, the Moon generally appears a deep ruddy color.

A little light falls on the Moon even at totality because the Earth’s atmosphere bends some sunlight into the shadow. A little light falls on the Moon even at totality because the Earth’s atmosphere bends some sunlight into the shadow. The light reaching the Moon is red because interactions with air molecules remove the blue light as it passes our atmosphere and is bent, as when we see the setting Sun. The light reaching the Moon is red because interactions with air molecules remove the blue light as it passes our atmosphere and is bent, as when we see the setting Sun.

A solar eclipse begins with a crescent “slice” taken out of the Sun’s edge as the Moon cuts across its disk. When the Moon’s disk completely covers the Sun, shadows become crisp and distorted, and sunlight filters through leaves as tiny bright crescents. A solar eclipse begins with a crescent “slice” taken out of the Sun’s edge as the Moon cuts across its disk. When the Moon’s disk completely covers the Sun, shadows become crisp and distorted, and sunlight filters through leaves as tiny bright crescents.

In one heartbeat you are plunged into darkness, and the corona of the Sun – its outer atmosphere – gleams around the Moon’s black disk. In one heartbeat you are plunged into darkness, and the corona of the Sun – its outer atmosphere – gleams around the Moon’s black disk. In just a few minutes, the Moon’s orbit uncovers the Sun, and it is daylight again.

annular eclipse annulus An annular eclipse occurs when the Sun and Moon are exactly in line, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulus, surrounding the outline of the Moon.

THIS IS NOT AN ECLIPSE!!! What is this?