Consequences of revolution of the Moon

There are two main consequences of the revolution of the Moon. The Moon revolves around the Earth is an elliptical path. Thus it is near(perigee) and far(apogee) from the Earth in every month. Due to this, there are two effects

1. Tides
2. Eclipses

Tides: Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.

Most places in the ocean usually experience two high tides and two low tides each day (semidiurnal tide), but some locations experience only one high and one low tide each day (diurnal tide). The times and amplitude of the tides at the coast are influenced by the alignment of the Sun and Moon, by the pattern of tides in the deep ocean  and by the shape of the coastline and near-shore bathymetry

Tides vary on timescales ranging from hours to years due to numerous influences. To make accurate records, tide gauges at fixed stations measure the water level over time. Gauges ignore variations caused by waves with periods shorter than minutes. These data are compared to the reference (or datum) level usually called mean sea level.

While tides are usually the largest source of short-term sea-level fluctuations, sea levels are also subject to forces such as wind and barometric pressure changes, resulting in storm surges, especially in shallow seas and near coasts.

Tidal phenomena are not limited to the oceans, but can occur in other systems whenever a gravitational field that varies in time and space is present. For example, the solid part of the Earth is affected by tides.

Tide changes proceed via the following stages:

• Sea level rises over several hours, covering the intertidal zone; flood tide.
• The water rises to its highest level, reaching high tide.
• Sea level falls over several hours, revealing the intertidal zone; ebb tide.
• The water stops falling, reaching low tide.

Tides produce oscillating currents known as tidal streams. The moment that the tidal current ceases is called slack water or slack tide. The tide then reverses direction and is said to be turning. Slack water usually occurs near high water and low water. But there are locations where the moments of slack tide differ significantly from those of high and low water.

Tides are most commonly semi-diurnal (two high waters and two low waters each day), or diurnal (one tidal cycle per day). The two high waters on a given day are typically not the same height (the daily inequality); these are the higher high waterand the lower high water in tide tables. Similarly, the two low waters each day are the higher low water and the lower low water. The daily inequality is not consistent and is generally small when the Moon is over the equator.

Eclipses: There are three types of eclipses

1. Solar Eclipse: The Solar Eclipse is caused by the movement of the Moon. The Moon, while revolving around the Earth, comes in between the Earth and the Sun and the light rays from the Sun are blocked by the Moon, which casts a shadow on the Earth. This is known as the Solar eclipse. But there are two types in Solar Eclipses
   
   
   
             1) Total Solar Eclipse: This is caused in the Umbra region of the shadow
             2) Partial Solar Eclipse: This is caused in the penumbra region of the shadow
   
   
2. Lunar Eclipse:   A lunar eclipse is when the Earth comes between the Sun and the Moon causing a shadow of Earth on the Moon. The shadow can partially or totally cover the Moon, giving us partial and total eclipses.
   Unlike solar eclipses, lunar eclipses are obviously safe to observe without protective gear for the eyes. You may notice that the moon looks spectacularly bright just before and after the eclipse. The Moon's surface is rather reflective, and close to the time of a lunar eclipse you are seeing the most direct reflection possible from the Moon's surface. If it is a very clear night, you will get a beautiful view of the moon. You will see various phases of illumination similar to those observed over the course of a lunar cycle.
   A lunar eclipse occurs when the full Moon lines up precisely with the Earth and the Sun, and the Earth's shadow falls on the Moon. Greek astronomers had figured that out over 2000 years ago, and knew that the curved shadow on the Moon indicated that the Earth was a sphere.
   
   

   

   The most recent total lunar eclipse was on December 21, 2010,
   seen here from California near greatest eclipse.

   
   
   
   
   
   
   
3. Annular Solar Eclipse: Annular Solar Eclipse is caused when the Moon is exactly between the Sun and the Earth in such a way that the light rays converge to become an antumbra region from where the Sun looks like a ring when seen from the Earth. This is the Annular Solar Eclipse.