Moon eclipses

We  see  a moon eclipse, when the moon enters into the shadow of the Earth. This happens at full moon. Normally the moon does not pass the shadow of the Earth.  The moon passes unter the shadow or over the Earth's shadow. The Earth throws a shadow, because she is illuminated by the sun. This shadow consists of a lighter shadow, the penumbra, and a darker shadow in the middle of the cone. When the full moon enters the penumbra, the moon will get a little darker. When the moon moves on, and enters the darker shadow, the Moon changes his light from grey to red. The red can be very dark, or be of  a lighter red or is even orange.  When the moon is covered by the umbra. she shines in a dark copper-colored light.  Sometimes the moon is not totally covered by the shadow of the Earth, but only a part of the lunar disc is covered by the shadow. This moon ecclipse is callaed partial  lunar eclipse. 

Why do we always see the same side of the moon - Tidal Lock

In 27 days the moon surrounds  the earth.   In 27 days the moon also spins around itself. This phenomenon is called tidal lock. Exoplanets sometimes come very close to a star.  Wen a celestial object comes  very close to a star, this object can also be torn apart by the gravitational forces.  This sometimes happens to moons of the big planets in our solar system.   This  happend to moons, rocks that came to close to Jupiter or Saturn. 

In distant future no wonderful sun ecclipses

 But don’t panic:. Our Moon will not be torn apart. Because the moon  has the tendency to escape. In the future the moon will be so far away from the Earth, that there will be only ring ecclipses, not full sun ecclipses,  for the sun cannot be totally covered by the moon. 

The revolution of the Moon in 27 day is aloo called the sideral month, (the time when we can see the same star again). The duration of the Lunar phases, (from full-moon to full.moon) is 29 days. This duration is called the synodic month, from one synode to the next.     

Where Does The Rings of Saturn Come From?

The rings of Saturn consist of rock and ice. The rocks are the remnant of a moon that had been torn by the gravitational forces of Saturn. The ice particles come his moon Enceladus. Cold Geysires on  Enceladus' surface are constantly throwing particles into space. All gas planets have rings. Uranus has rings, and even Jupiter  has very thin rings. 

The Ecliptic

The ecliptic is also called the zodiac. The constellations our ancestors saw,  go back to  Greek mythology, and summerian mythology.  The point at which the sun, passes the equator from south to north at the beginning of the spring, is called the vernal equinox (spring point). When autum beginns the sun desendes at the  equator at the autum equinox  (autum point)   We find on the ecliptic the constellation of Pisces,  Aries,  Aquarius,  Capricorn,  Sagittarius,  Libra, Virgo,  Lion, Cancer,  Gemini and Taurus.

The Precession of the Earth's Axis

The axis of the Earth describes a circle in a periord of 26 000 years. So the axis points to diffent polar stars. In 11,000 years Wega in the constellation Lyra will be our polar star at the northern hemisphere. The equinoctes are also wandering around the ecliptic. 2000 years ago the vernal equinox, also called the  the point of Aries,  was situated in the constellation of Aries. In the past 2000 years the vernal equinox had wandered  into the Pisces.  

The expanding Universe

In the 1920s, Hubble was not only concerned with the expanding universe in America, but also LeMaitre. LeMaitre worked at this time in America working on various Institutions. As a result, he became aware of the measurements of the velocities of the Milky Way galaxies by Vesto Slipher. Slipher worked at Lowell Observatory. Hubble published at this time on the distances of Andromeda galaxy and the redshifts and thus the expansion of the universe. The LeMaitres publications have not become as popular in science as Hubble's.