The moon is the astronomical body which orbits around the Earth once per month. The moon is fifth largest satellite in the solar system. It is second brightest object after the sun visible in sky although it has not own light. The moon is the natural satellite of the earth and also known as “Luna”. Beyond the earth, moon is the only place where the human placed his foot.
On 13th September 1959, moon was first visited by Soviet Union Spacecraft Luna 2. On 20th July 1969, Apollo 11 was the first United state’s crew mission which was successful with landing on moon. Neil Armstrong (1930-2012) and Edwin Buzz Aldrin (1930- ) were two American astronauts who put their legs on moon’s surface.
Properties of Moon
- The moon is the natural satellite of the earth which is brightest after the sun but has not own light.
- Average distance from the moon’s center to that of the earth is 384402km.
- Diameter of moon is 3479km which is ¼ of the earth.
- The mass of the moon is 7.35 X 1022 kilograms which is 1/80 of the earth.
- Density of the moon is 3.3 gm/cm3 and surface gravity is 0.17
- Temperature on the surface of moon is 107 oC on day and -153 oC at night.
- The moon orbits around the earth in 27.332 days.
- We can see only one face of the moon from the earth because the moon’s rotation rate on its own axis and moon’s rotation around the earth is same. It is known as synchronous rotation or tidally locked.
- The moon is the cause of creation of tide in oceans.
Formation of Moon
According to the evidence the moon was formed 95 million years after the solar system developed. The earth and entire solar system was formed before 4.5 billion years ago. When the earth was in the stage of fully formed, there was a giant impact done between Thea and proto earth. Due to collision, iron core of thea would sunk into proto earth’s core and mantle of Thea accreted on the mantle of earth. Some of the material ejected due to this collision would have reached to the orbit around the earth and some material to the orbit around the sun. The materials which were orbiting around the earth quickly combined and made “Moon”. While the materials which were orbiting around the sun settled in Kepler orbit. The earth gained angular momentum and mass by this collision and the day also became about 5 hours longer than usual.
Structure of Moon
Similar to the earth, the moon has also inner Core, Mantle and Crust.
The outer surface of the moon with about 5km thickness is called “Crust”. The crust is mainly made of silicon, magnesium, oxygen, iron, calcium and aluminium. Beyond these some other elements like titanium, uranium, thorium, potassium and hydrogen are also present in crust.
The inner core is surrounded by “Mantle”. It covers most of the area of moon which is up to 50km distance from the surface of the moon. Main minerals of Mantle are olivine, orthopyroxene and clinopyroxene. Beyond the earth’s mantle it is more iron rich.
The inner “Core” is about 240 km radius which is made of metallic iron with small amount of sulfer and nickel. The temperature of the core is about 2600K but it is not enough to keep warm the outer surface of moon.
Surface of Moon
The moon’s surface is composed of impact craters, volcanoes, lava flows and depressions filled by magma.
The moon surface is visible as light and dark areas. The brighter surface is highland which is known as “Terrae” while darker surface is called “maria”. Mountains, heavy craters areas are covered in highlands which are about 4 to 5 km in height over average lunar surface while maria covers low lying plains which are 2 to 3km down to average lunar surface.
Moon’s surface is covered by number of craters which were formed by hitting the meteors on it which are having peaks in center and materials are thrown from crater forming like rays coming out from it. Second type of surface is multi-ringed basin which is formed by huge impact. Volcanoes, lava tubes, lava flows also seen on moon’s surface. The Moon has no true soil, it is called “Regolith” which is fine powder of rock fragments and volcanic glass particles.
Effect of moon on ocean’s tide
The gravitational attraction of the Moon and Sun makes the water in oceans bulge which is the reason of high and low tide in oceans. The Moon and sun plays important role for tides but moon’s effect is much more than sun because low distance of moon from the earth than the sun.
The moon’s gravitational force creates the tide is known “Tidal Force”. This tidal force bulges out the water of oceans on closet side and farthest side from the moon. It is called high tide.
Due to rotation of earth, our specific region on the earth passes through this bulge in each day so we face tide two times in a day. When we are in one of the bulges area we experience high tide and when we are not in that area we experience Low tide.
Extreme difference between high tide and low tide is experienced on Full moon and New moon when the sun, moon and earth are aligned and their gravitational forces pull ocean water in same direction. This tide is called “Spring Tide”.
On quarter moon or half moon, gravitational force of moon and sun counteract to each other so tidal range is low at that point which is called “Neap tide”.
The moon orbits the earth not in perfect circular path but in elliptical path. It has perigee (closest) and apogee (farthest) approaches from earth. There are two key features required for super moon, one is the moon is on perigee approach and moon is in full phase of brightness.
When the moon is closet (perigee) point to the earth in its elliptical path, it is appeared larger and brighter than as usual it is called “Super moon”. During this position, the moon is at 3,56,907 km away from earth compared to average 3,84,402 km distance. The Super moon is 7% to 15% larger and 30 % brighter than ordinary moon.
When the moon is at farthest (apogee) approach from the earth about 405000 km distance, it is called “Micro moon“.
The moon is visible when total lunar eclipse is done. The moon is covered by full shadow of the earth. The sunlight passes through earth’s atmosphere is bent and reflected toward the moon due to earth’s atmospheric effect which create the reddish colour of moon. It is called “Blood moon”.The reddish colour of moon depends on the dust and clouds presence in the earth’s atmosphere.
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Authored by BK Suthar.
This site is about various topics of astronomical and geographical things which present in universe and also surrounding us. It will give you information about various planets, incidents occurs in universe and also about nature.
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