Eclipses-Cycles

The sun is eclipsed whenever the moon comes between Earth and sun, while the moon is eclipsed whenever it passes into the sun’s shadow cast on Earth. As natural satellites (moons) and spacecraft orbiting and flying past another planet pass into the planet’s shadow, eclipses occur. An eclipsing binary system’s two-component stars orbit others in such a way as its orbital plane crosses over or very close to Earth, and each star eclipses the other regularly as seen from Earth. 

Eclipse Season

In an eclipse season, which lasts one or two months twice a year and occurs whenever the sun is close to the nodes of the moon’s orbit, up to three eclipses can arise. Since the relative geometry of the Sun, Moon, and Earth have shifted one month after this eclipse, it doesn’t happen every month. The time taken for the moon to reach a node, known as the draconic month, is shorter than the time taken for the moon to come to exact ecliptic longitude as that of the sun, known as the synodic month, that can be seen from Earth. The fundamental reason would be that the Earth (and Moon) has finished roughly 113 orbits around the sun during the duration that the moon has completed an orbit around the Earth: the moon must make up for this to restore into conjunction and opposition with the sun. Furthermore, the moon’s orbital nodes process westward in ecliptic longitude, taking around 18.60 years to complete an entire circuit; therefore, a draconic month is less than a sidereal month.

The period variation among synodic and draconic months is about 2+13 days in total. Similarly, as seen from Earth, the sun passes through nodes on its ecliptic course. The eclipse and draconic year seem to be the time it takes for the sun to return to a node: around 346.6201 days, which is approximately 120 years shorter than a sidereal year due to node motion.

Therefore, the new moon will fall near the opposite node around 5 or 6 lunations later. The sun will have also traveled to the opposite node in that period (half an eclipse year); therefore, the conditions will be favorable for one or even more eclipses.

Eclipse Cycles

Any eclipse cycle could be described as a combination of saros (s) and index I intervals, as can the gap between two eclipses.

Fortnight

A synodic month and a half (29.53 days). The Sun and Moon will still have migrated around 15° about a node (the moon now opposite wherever it was the last time); however, the luminaries might be in bounds enough to make an eclipse in the next syzygy. The partial solar eclipse on June 1, 2011, for instance, is guided by a total lunar eclipse on June 15, 2011, and another partial solar eclipse on July 1, 2011.

Synodic month

Furthermore, two instances one synodic month apart with the Moon and Sun at 29° apart on either side of the node, which both could induce a partial eclipse. It’s a penumbral lunar eclipse for a lunar eclipse.

Pentalunex

There are five synodic months in a year. Solar or lunar eclipses can happen one, five, or six synodic months apart.

Semester

A lunar year and a half. In an 8-eclipse cycle, eclipses would occur approximately one semester apart at opposite nodes. So because the number of anomalistic, draconic, or tropical months or years is near to a half-integer, any semester’s solar eclipse may rotate among hemispheres or total as well as annular eclipses. As a result, each year could only have one total eclipse and annular eclipse. (In the case of a lunar eclipse, eclipses would occur exactly one semester apart at alternating nodes in an 8-eclipse cycle.)

Each lunar eclipse would shift between the borders of Earth’s shadow each semester, and between Lunar Perigee or Lunar Apogee, due to the proximity of a half-integer of anomalistic, draconic months, plus tropical years. As a result, only one Lunar Perigee or Lunar Apogee can occur.)

Saros Series and Inex Series

A given saros plus index series could be ascribed to any eclipse. In the Gregorian calendar, the year of a solar eclipse is roughly provided by:

year = 28.945 × number of the saros series + 18.030 × number of the index series − 2882.55

The integer part will give the year AD when it becomes larger than 1, and when it is negative, the year BC is acquired by adding 2 to the integer part. For example, the eclipse in saros series 0 and index series 0 occurred in the middle of 2884 BC.

Conclusion

Eclipse seasons are times when eclipses are not always possible but also required. There are at least two eclipses (one solar and one lunar, in any order). A total of three eclipses (lunar/solar/lunar or solar/lunar/solar) are probable. I hope now you understand all about the eclipse cycle. For better understanding, you must read this information thoroughly. After reading this information, you’ll be able to clear all your doubts easily.