Size of the Moon compared to the Earth
Phases of the Moon
The diagram below highlights the eight different phases of the Moon: Full Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter and Waning Crescent.
Facts about the Moon
- There is no dark side of the Moon. Both sides of the Moon see the same amount of sunlight, however because the Moon is tidally locked to Earth, only one face of the Moon is ever seen from Earth. This is because the Moon rotates around its axis in exactly the same time it takes to orbit Earth. The side we see from Earth is reflected by sunlight, while the “dark” side has only been seen by the human eye from a spacecraft and lies in darkness.
- The rise of fall of tides on Earth is caused by the Moon. Two bulges exist due to the gravitational pull the Moon exerts. One is on the side facing the Moon and the other on the side facing away from it. These bulges move around the oceans as the Earth rotates which causes the high and low tides found across the globe.
- The Moon is slowly drifting away from Earth. Every year, the Moon moves roughly 3.8 cm further away from Earth. Scientific estimates suggest this will continue to happen for 50 billion years. At that point, the Moon will take 47 days to orbit the Earth, compared to the current time of 27.3 days.
- You weigh much less on the Moon. A common fact about the Moon is that it has much weaker gravity than Earth. This is because its smaller mass and you would weight one sixth (about 16.5%) of your Earth weight while on the Moon.
- Only 12 people have ever walked on the Moon. It started with Neil Armstrong in 1969 as part of the Apollo 11 mission and ended with Gene Cernan in 1972 on the Apollo 17 mission. A total of 12 American males have walked on the Moon. Since 1972, all lunar missions have been unmanned spacecraft.
- The Moon will be visited by man again. NASA has plans to set up a permanent space station on the Moon, and man may walk on the Moon again sometime around 2019-2020.
- The USA considered detonating a nuclear bomb on the Moon in the 50s. A secret project during the height of the cold war – codenamed “Project A119”, also known as “A Study of Lunar Research Flights” was planned as a “show of strength” at a time when they were falling behind the USSR in the space race.
- There is no atmosphere on the Moon. There is no protection for the surface from cosmic rays, meteorites, asteroids, comets, or solar winds. This is why the Moon has such huge temperature variations and it is covered with impact craters. The lack of atmosphere also means no sound can be heard on the Moon and the sky is always black.
- The Moon has quakes. The gravitational pull of Earth causes small moonquakes several kilometres beneath the surface – causing ruptures and cracks. It is believed that, like Earth, the Moon has a molten core.
- The Moon is the fifth largest natural satellite. It is much smaller than the major moons of Saturn and Jupiter at 3,475 km in diameter, but the Moon is the largest in relation to the size of the planet it orbits. Earth is about 80 times the volume of the Moon, yet they are the same age. A popular theory is that the Moon was once part of the Earth and formed from a chunk broken off by a huge object that collided with Earth while it was still young.
- The “Man in the Moon” is an optical illusion seen when looking at the Moon’s surface from Earth. It is a result of the contrast between the lighter lunar highlands and darker lunar plains.
- The diameter of the Moon is the same distance from New York City to Phoenix, Arizona.
- There are over 500,000 craters on the Moon’s surface.
- A lunar eclipse is when the Earth passes between the Sun and the Moon and a shadow is cast on the Moon.
- A solar eclipse is when the Moon passes between the Sun and the Earth – causing a shadow to project onto the Earth’s surface.
More information and facts about the Moon
The Moon is unique in that it is the only spherical satellite orbiting a terrestrial planet. The reason for its shape is a result of its mass being great enough so that gravity pulls all of the Moon’s matter toward its center equally.
Another distinct property the Moon possesses lies in its size compared to the Earth. At 3,475 km, the Moon’s diameter is over one fourth that of the Earth’s. In relation to its own size, no other planet has a moon as large.
For its size, however, the Moon’s mass is rather low. This means the Moon is not very dense. The explanation behind this lies in the formation of the Moon. It is believed that a large body, perhaps the size of Mars, struck the Earth early in its life. As a result of this collision a great deal of the young Earth’s outer mantle and crust was ejected into space. This material then began orbiting Earth and over time joined together due to gravitational forces, forming what is now Earth’s moon. Furthermore, since Earth’s outer mantle and crust are significantly less dense than its interior explains why the Moon is so much less dense than the Earth.
When viewed from Earth, the many impact craters fround on the Moon’s surface are visible. The reason for this is simple. Unlike the Earth, the Moon is not geologically active, and so it does not possess an atmosphere nor does it possess volcanic activity. Consequently, the Moon does not undergo resurfacing as does the Earth.