Moon Zoom 2000x Facts and Formation
02 August 2018
The Moon (or Luna) is the Earth’s only natural satellite and was formed 4.6 billion years ago around some 30–50 million years after the formation of the solar system. The Moon is in synchronous rotation with Earth meaning the same side is always facing the Earth. The first unmanned mission to the Moon was in 1959 by the Soviet Lunar Program with the first manned landing being Apollo 11 in 1969.
- The dark side of the moon is a myth.
In reality both sides of the Moon see the same amount of sunlight however only one face of the Moon is ever seen from Earth. This is because the Moon rotates around on its own axis in exactly the same time it takes to orbit the Earth, meaning the same side is always facing the Earth. The side facing away from Earth has only been seen by the human eye from spacecraft.
- The rise and fall of the tides on Earth is caused by the Moon.
There are two bulges in the Earth due to the gravitational pull that the Moon exerts; one on the side facing the Moon, and the other on the opposite side that faces away from the Moon, The bulges move around the oceans as the Earth rotates, causing high and low tides around the globe.
- The Moon is drifting away from the Earth.
The Moon is moving approximately 3.8 cm away from our planet every year. It is estimated that it will continue to do so for around 50 billion years. By the time that happens, the Moon will be taking around 47 days to orbit the Earth instead of the current 27.3 days.
- A person would weigh much less on the Moon.
The Moon has much weaker gravity than Earth, due to its smaller mass, so you would weigh about one sixth (16.5%) of your weight on Earth. This is why the lunar astronauts could leap and bound so high in the air.
- The Moon has only been walked on by 12 people; all American males.
The first man to set foot on the Moon in 1969 was Neil Armstrong on the Apollo 11 mission, while the last man to walk on the Moon in 1972 was Gene Cernan on the Apollo 17 mission. Since then the Moon has only be visited by unmanned vehicles.
- The Moon has no atmosphere.
This means that the surface of the Moon is unprotected from cosmic rays, meteorites and solar winds, and has huge temperature variations. The lack of atmosphere means no sound can be heard on the Moon, and the sky always appears black.
- The Moon has quakes.
These are caused by the gravitational pull of the Earth. Lunar astronauts used seismographs on their visits to the Moon, and found that small moonquakes occurred several kilometres beneath the surface, causing ruptures and cracks. Scientists think the Moon has a molten core, just like Earth.
- The first spacecraft to reach the Moon was Luna 1 in 1959.
This was a Soviet craft, which was launched from the USSR. It passed within 5995 km of the surface of the Moon before going into orbit around the Sun.
- The Moon is the fifth largest natural satellite in the Solar System.
At 3,475 km in diameter, the Moon is much smaller than the major moons of Jupiter and Saturn. Earth is about 80 times the volume than the Moon, but both are about the same age. A prevailing theory is that the Moon was once part of the Earth, and was formed from a chunk that broke away due to a huge object colliding with Earth when it was relatively young.
- The Moon will be visited by man in the near future.
NASA plans to return astronauts to the moon to set up a permanent space station. Mankind may once again walk on the moon in 2019, if all goes according to plan.
- During the 1950’s the USA considered detonating a nuclear bomb on the Moon.
The secret project was during the height cold war was known as “A Study of Lunar Research Flights” or “Project A119” and meant as a show of strength at a time they were lagging behind in the space race.
The Moon formed 4.51 billion years ago,[f] some 60 million years after the origin of the Solar System. Several forming mechanisms have been proposed, including the fission of the Moon from Earth's crust through centrifugal force (which would require too great an initial spin of Earth), the gravitational capture of a pre-formed Moon (which would require an unfeasibly extended atmosphere of Earth to dissipate the energy of the passing Moon), and the co-formation of Earth and the Moon together in the primordial accretion disk (which does not explain the depletion of metals in the Moon). These hypotheses also cannot account for the high angular momentum of the Earth–Moon system.[
The prevailing hypothesis is that the Earth–Moon system formed after an impact of a Mars-sized body (named Theia) with the proto-Earth (giant impact). The impact blasted material into Earth's orbit and then the material accreted and formed the Moon.
The Moon's far side has a crust that is 30 mi (48 km) thicker than that of the near side. This is thought to be because the Moon fused from two different bodies.
This hypothesis, although not perfect, perhaps best explains the evidence. Eighteen months prior to an October 1984 conference on lunar origins, Bill Hartmann, Roger Phillips, and Jeff Taylor challenged fellow lunar scientists: "You have eighteen months. Go back to your Apollo data, go back to your computer, do whatever you have to, but make up your mind. Don't come to our conference unless you have something to say about the Moon's birth." At the 1984 conference at Kona, Hawaii, the giant impact hypothesis emerged as the most popular.
Before the conference, there were partisans of the three "traditional" theories, plus a few people who were starting to take the giant impact seriously, and there was a huge apathetic middle who didn’t think the debate would ever be resolved. Afterward, there were essentially only two groups: the giant impact camp and the agnostics.
Giant impacts are thought to have been common in the early Solar System. Computer simulations of giant impacts have produced results that are consistent with the mass of the lunar core and the angular momentum of the Earth–Moon system. These simulations also show that most of the Moon derived from the impactor, rather than the proto-Earth. However, more recent simulations suggest a larger fraction of the Moon derived from the proto-Earth.
Other bodies of the inner Solar System such as Mars and Vesta have, according to meteorites from them, very different oxygen and tungsten isotopic compositions compared to Earth. However, Earth and the Moon have nearly identical isotopic compositions. The isotopic equalization of the Earth-Moon system might be explained by the post-impact mixing of the vaporized material that formed the two, although this is debated.
The impact released a lot of energy and then the released material re-accreted into the Earth–Moon system. This would have melted the outer shell of Earth, and thus formed a magma ocean. Similarly, the newly formed Moon would also have been affected and had its own lunar magma ocean; its depth is estimated from about 500 km (300 miles) to 1,737 km (1,079 miles).
While the giant impact hypothesis might explain many lines of evidence, some questions are still unresolved, most of which involve the Moon's composition.
In 2001, a team at the Carnegie Institute of Washington reported the most precise measurement of the isotopic signatures of lunar rocks. To their surprise, the rocks from the Apollo program had the same isotopic signature as rocks from Earth, however they differed from almost all other bodies in the Solar System. Indeed, this observation was unexpected, because most of the material that formed the Moon was thought to come from Theia and it was announced in 2007 that there was less than a 1% chance that Theia and Earth had identical isotopic signatures. Other Apollo lunar samples had in 2012 the same titanium isotopes composition as Earth, which conflicts with what is expected if the Moon formed far from Earth or is derived from Theia. These discrepancies may be explained by variations of the giant impact hypothesis.
|Written by: Luis Clement|