Natural Satellite

The Moon is Earth's only natural satellite and he fifth largest satellite in the Solar System. It is the largest natural satellite of a planet in the Solar System relative to the size of its primary, a quarter the diameter of Earth and 1⁄81 its mass . The Moon is the second densest satellite after Io, a satellite of Jupiter.

 The Moon is thought to have formed nearly 4.5 billion years ago, not long after the Earth. Although there have been several hypotheses for its origin in the past, the current most widely accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars-sized body. The Moon is the only celestial body other than Earth on which humans have set foot.

 sometime in the early stage of the Solar System–about four and a half billion years ago–a large proto-Earth collided with a Mars-sized body named “Theia,” causing a huge cloud of material from both bodies to fly out into space. Some of the material remained in the Earth’s orbit and coalesced into the Moon. It’s a fascinating hypothesis.

Around the Solar System, multiple moons are the rule. Jupiter has 63 natural satellites, even Mars has two asteroid-like moons.

Does the Earth have any other moons?

Could Earth have more than one?

Officially, the answer is no. The Earth has a single moon. But Today only. It’s possible Earth had more than one moon in the past, millions or even billions of years ago.For example, Mars has two Moons, but not for long. It’s also possible that the Earth might capture a Moon in the future.

How many moons are there in the Solar System? according NASA’s  information. Mercury and Venus-0, Earth-1,Mars-2,Jupiter-63,Saturn-60,

Uranus-27,Neptune-13.The number of known moos has been steadily growing with the improvement of technology. The number has nearly doubled so.

Some of the moons in the solar system are known to have volcanoes, cryptovolcanos, and tectonic activity. Some are thought to have sub-surface oceans. Io is the most volcanically active body that scientists know of. At least four moons still have active tectonic plates. A few have observed atmospheres containing oxygen. Europa, among others is thought to be capable of supporting life as we know it, although this is unproven as yet. Iron metallic cores are not uncommon along with moons that have their own magnetic fields.

Ganymede is the largest moon in the solar system and our Moon is the fifth largest.

 It is in synchronous rotation with Earth, always showing the same face; the near side is marked with dark volcanic maria among the bright ancient crustal highlands and prominent impact craters. It is the brightest object in the sky after the Sun, although its surface is actually very dark, with a similar reflectance to coal. Its prominence in the sky and its regular cycle of phases have since ancient times made the Moon an important cultural influence on language, calendars, art and mythology. The Moon's gravitational influence produces the ocean tides and the minute lengthening of the day. The Moon's current orbital distance, about thirty times the diameter of the Earth, causes it to appear almost the same size in the sky as the Sun, allowing it to cover the Sun nearly precisely in total solar eclipses.

The Moon is thought to have formed nearly 4.5 billion years ago, not long after the Earth. Although there have been several hypotheses for its origin in the past, the current most widely accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars-sized body. The Moon is the only celestial body other than Earth on which humans have set foot.

 The Moon is the only celestial body on which humans have landed. While the Soviet Union's Luna programme was the first to reach the Moon with unmanned spacecraft in 1959, the United States' NASA Apollo program achieved the only manned missions to date, beginning with the first manned lunar orbiting mission by Apollo 8 in 1968, and six manned lunar landings between 1969 and 1972—the first being Apollo 11. These missions returned over 380 kg of lunar rocks, which have been used to develop a detailed geological understanding of the Moon's origins , the formation of its internal structure, and its subsequent history.

After the Apollo 17 mission in 1972, the Moon has been visited only by unmanned spacecraft, notably by the final Soviet Lunokhod rover. Since 2004, Japan, China, India, the United States, and the European Space Agency have each sent lunar orbiters. These spacecraft have contributed to confirming the discovery of lunar water ice in permanently shadowed craters at the poles and bound into the lunar regolith. Future manned missions to the Moon have been planned, including government as well as privately funded efforts. The Moon remains, under the Outer Space Treaty, free to all nations to explore for peaceful purposes.

some 30–50 million years after the origin of the Solar System.These include the fission of the Moon from the Earth's crust through, which would require too great an initial spin of the Earth, the gravitational capture of a pre-formed Moon, which would require an unfeasibly extended atmosphere to the energy of the passing Moon, and the co-formation of the Earth and the Moon together in the primordial accretion disksome 30–50 million years after the origin of the Solar System.

These include the fission of the Moon from the Earth's crust through centrifugal forces, which would require too great an initial spin of the Earth, the gravitational capture of a pre-formed Moon, which would require an unfeasibly extended atmosphere of the Earth to dissipate the energy of the passing Moon, and the co-formation of the Earth and the Moon together in the primordial accretion disk, which does not explain the depletion of metallic iron in the Moon. These hypotheses also cannot account for the high angular momentum of the Earth–Moon system, which does not explain the depletion of metallic iron in the Moon. These hypotheses also cannot account for the high angular momentum of the Earth–Moon system.

The Moon makes a complete orbit around the Earth with respect to the fixed stars about once every 27.3 days (its sidereal period). However, since the Earth is moving in its orbit about the Sun at the same time, it takes slightly longer for the Moon to show the same phase to Earth, which is about 29.5 days (its synodic period).

The Moon is a differentiated body: it has a geochemically distinct crust, mantle, and core. The moon has a solid iron-rich inner core with a radius of 240 kilometers and a fluid outer core primarily made of liquid iron with a radius of roughly 300 kilometers. Around the core is a partially molten boundary layer with a radius of about 500 kilometers. This structure is thought to have developed through the fractional crystallization of a global magma ocean shortly after the Moon's formation 4.5 billion years ago.

which is more iron rich than that of Earth. Geophysical techniques suggest that the crust is on average ~50 km thick.

One-half of the Moon appears to be illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is increasing. The right half of the Moon appears lighted and the left side of the Moon appears dark.  During the time between the New Moon and the First Quarter Moon, the part of the Moon that appears lighted gets larger and larger every day, and will continue to grow until the Full Moon.

 Moon's gravity is 1/6 of the Earth's, if an 80 kg person went to the moon his weight is 13.3 kg only.

photos:red moon:

Red and orange tinted Moon, as seen from Earth during a lunar eclipse, where the Earth comes between the Moon and Sun.

The Moon is a differentiated body: it has a geochemically distinct crust, mantle, and core. The Moon has a solid iron-rich inner core with a radius of 240 kilometers and a fluid outer core primarily made of liquid iron with a radius of roughly 300 kilometers. Around the core is a partially molten boundary layer with a radius of about 500 kilometers.

The Moon has an atmosphere so tenuous as to be nearly vacuum, with a total mass of less than 10 metric tons.

Eclipses can only occur when the Sun, Earth, and Moon are all in a straight line.

The Moon gives off no light of its own but reflects sunlight from its rocky surface. the moon shines is that it reflects the light of the Sun. What we call moonshine is actually sunshine  reflected by the Moon.

Another one is earthshine, meaning sunlight reflected by the Earth. We have only one way to see it. That occurs because some of the earthshine falls on the Moon and is reflected back to Earth again. By this dim light we can sometimes see the outline of the whole moon behind the crescent of a new moon.