On Eclipses
On Eclipses
by Anton Gigoryev
An Eclipse is no other than an Interception
or privation of the light of the luminaries,
viz. Of the Sun and Moon, A lunar Eclipse, or of the Moon,
is privation of light in the Moon, occasioned by the interposition
of the Earth between the Sun and the Moon;
a Solar Eclipse is an interception or obscuration
of the light of the Sun, caused by interposition
of the Moons body between the Sun and our sight.
William Lilly
Solar eclipses happen, when the Moon is placed between the Sun and the Earth, and the Moon hides by its own body the Sun. It happens at newmoons. Lunar eclipses happens, when the Earth is placed between the Sun and the Moon. In this case, the Moon is got into Earth’s shadow, and is not lighted by the Sun. It happens at fullmoons.
Lunar Eclipses
Lunar eclipses happen, when the Moon is going through the Earth’s penumbra and umbra. There are three cases:
- When the Moon immerses into the Earth’s umbra entirely. There is a total lunar eclipse in this case (generally, it is marked in ephemerides by T). A man on earth will see the whole Moon, step by step, become eclipsed.
- When only some part of the Moon immerses into the Earth’s umbra. There is a partial lunar eclipse in this case (generally, it is marked in ephemerides by P). A man on earth will see in this case, that only a part of the Moon, step by step, become eclipsed.
- When the Moon doesn’t immerse into the Earth’s umbra at all, but the Moon only passes through the Earth’s penumbra. It is called an appulse or penumbral lunar eclipse (generally, it is marked in ephemerides by A). A man on earth will not see any eclipse at all, because a Moon’s immersion into the Earth’s penumbra is practically invisible from the Earth.
Though astronomers call Moon’s pass through the Earth’s penumbra an eclipse, but from the astrological point of view it is not an eclipse, because in this case the Moon is not eclipsed for man’s eyes. Analysis of ancient astrological texts shows, that ancient astrologers did not take a penumbra into consideration at all.
The beginning of lunar eclipse is the beginning of Moon’s immersion into the Earth’s umbra, or the first umbra contact. The end of lunar eclipse is the Moon’s leaving from the Earth’s umbra, or the last umbra contact. A duration of eclipse is the time between first umbra contact and last umbra contact.
A lunar eclipse is visible at one and the same time on all that part of the Earth, where the Moon is placed above the horizon at this moment. For all the territories, where an eclipse is visible, it happens at one and the same moment, and lasts the same time. Because an eclipse is lasting some time, there are territories, where the eclipsed Moon is rising or setting.
Solar Eclipses
Solar eclipses happen, when the Moon is between the Sun and the Earth, the Moon hides by its own body the Sun’s light, and a shadow spot is falling onto the Earth surface. There is a more dark area in the center of this spot, it is a umbra. A total solar eclipse is visible in those places of the Earth, which are in umbra. A lighter part of this spot is a penumbra. A partial solar eclipse is visible in those places of the Earth, which are in penumbra. Of course, there is no umbra in partial solar eclipse, but only penumbra.
In contrast to lunar eclipse, a penumbra is visible in solar eclipse. Penumbra is a phase of partial eclipse. Therefore a beginning of solar eclipse is first penumbra contact, and an end of solar eclipse is last penumbra contact. The duration of a solar eclipse is the time between first penumbral contact and last penumbral contact.
Unlike lunar eclipse, solar eclipse is visible only in certain area on the Earth – the area of visibility. This area includes parts, wherein the eclipsed Sun is rising and setting. A solar eclipse does not appear at the same time at every point on the earth at which it is visible. Rather, an eclipse shadow moves from west to east at a speed of about 36 kilometres per minute. So the real eclipse takes place at different times at different places.
The track of umrbra spot on the earth surface is called the path of eclipse. Total solar eclipse is visible there. The track of penumba spot makes the area of visibility. There is partial solar eclipse in this area. The farther from the eclipse path, the less part of the Sun is obscured in the eclipse.
