Question #29383

1 Answer
Oct 26, 2016

See explanation


The phases are created by the day-night spin of Moon, with respect

to sunlight. This period is is nearly two fortnights. As seen from the

Earth, the lighted surface of the its satellite moon appears to

grow and wane, alternately, within one lunar month. This causes

phases called new-crescent-gibbous-full -gibbous-crescent-new

cycle of phases.

In the Sun-Moon-Earth alignment, it is New Moon.

In the Sun_Earth- Moon alignment, it is Full Moon.

Earth orbits Sun in a plane called ecliptic.Moon orbits Earth as a

satellite in a plane inclined to ecliptic by about #5^o#.

In almost perfect alignments of the centers of this triad, New Moon

hides Sun for Solar Eclipse and Earth hides sunlight to Moon on

New Moon and creates Lunar Eclipse..

Each space body that attracts towards near and far other space

bodies (including you and me ) attracts by a force

#= (gamma m_1 m_2) / r_(12)^2#, where

#gamma# = universal gravitational constant, #m_1# = mass of the

attracting body, #m_2# = mass of the attracted body and #r_(12)# =

the distance between the two.

The force is more on close by bodies.

For the water bodies of the Earth that includes seas, the resultant

attraction of (greater ) lunar force and ( smaller ) force from the Sun

is a maximum around Full Moon Sun-Moon-Earth alignment and a

minimum around New Moon Sun-Earth-Moon alignment. And this

causes Spring (maximum wave ) tides and Neap ( minimum wave )

tides, respectively. Owing to this rise and fall, seawater enters and

recedes, alternately, in river mouths, bays and estuaries.