[dropcap]M[/dropcap]oon. The only natural satellite of earth. Moon has been a piece of scientific as well as literary significance for a long time. Till date, new discoveries are made about it.
Ever wondered how the moon came into existence?
It wasn’t formed at the same time as earth but hundred million years later. There is this, giant impact hypothesis. According to which moon was created when a celestial body is known as theia, roughly the size of Mars collided with early earth and our moon came to existence!
There are many interesting characteristics of our only natural satellite, which holds the fascination of science:
The Moon’s center of mass is offset from its geometric center by about 2 km in the direction toward the Earth. Also, the crust is thinner on the near side. It doesn’t have uniform concentration throughout.
Moon doesn’t have any magnetic field like earth, but some of its surface rocks exhibit remanent magnetism indicating magnetic activities in the past.
Moon has near to no atmosphere. To be precise moon has a very thin atmosphere, almost vacuum, compared to earth’s atmosphere. Consisting of some unusual gases, including sodium and potassium, which are not found in the atmospheres of Earth, Mars or Venus. Due to its thin atmosphere, Moon is very hot at day time and very cold at nights.It is also exposed to the solar winds due to the same reason.
Moon’s gravitational force is lesser than earth, resultantly, a man weighs less on moon and also can bounce the way astronauts do!
We always see the same side of moon 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 can only been seen from spacecraft.
It takes almost 29 days(approximately) for the Moon to complete one revolution about earth.
Only 12 humans have set their foot on moon. Interestingly all of them have been Americans and that too, all males!
The very first unmanned spacecraft that reached moon was Soviet Union’s Luna 2 mission 1959.
The first manned spacecraft to reach moon was United States’ Apollo 11 in 1969.
There are 8 phases of moon cycle.
image credit:https://astronavigationdemystified.com/the-moon/
New Moon
A new moon is dark, occurring when the Moon’s orbit creates a Sun-Moon-Earth order. The Sun illuminates the Moon, but only on the side that doesn’t face Earth, hence, we can’t see it.
Crescent Moons
Crescent moons last about a week. The first crescent moon of the cycle is called the waxing crescent,as it is in the half of the cycle that leads to the full moon. The other crescent is called the waning crescent, the last phase before the new Moon occurs.
Full Moon
The full Moon happens when the Moon moves into a position that creates a Sun-Earth-Moon order. Sunlight beams past the Earth to fully illuminate the whole side of the Moon facing the earth.
Gibbous Moons
Gibbous moons, similarly as crescent moons, are either waxing or waning, depending on whether they’re in the first or second half of the Moon cycle. The waxing and waning gibbous moons,each are more than half-full and stays for about a week.
Quarter Moons
Quarter moons are called so because only a quarter of the Moon’s sphere is illuminated by the sun. The first quarter moon has its left side illuminated and appears during the waxing part of the cycle, while the right side is illuminated in the waning phase.
Moon’s gravitation pull towards earth is the cause of tides.
image credit:https://www.metoffice.gov.uk/learning/ocean/tides
These tides can be classified into three types:
1. Spring tides:
When the sun and moon are aligned, there are exceptionally strong gravitational forces, causing very high and very low tides which are called spring tides. These tides occur on full moon or new moon days.
2. Neap tides:
When the sun and moon are not aligned, the gravitational forces cancel each other out, and the tides are not as high and low as it is in the spring tides. These are called neap tides. These tides occur during quarter moons.
3. Proxigean spring tide:
It is a rare, unusually high tide. This very high tide occurs when the moon is unusually close to the Earth and in the New Moon phase. The proxigean spring tide occurs once in every 1.5 years.
Eclipse is yet another intriguing phenomenon associated with the moon.
An eclipse takes place when one heavenly body such as a moon or planet moves into the shadow of another heavenly body. There are two types of eclipses on Earth:Lunar Eclipse and Solar eclipse.
image credit:http://itsco.org/blog/2017-solar-eclipse
When Earth passes directly between the sun and the moon, a lunar eclipse takes place.
image credit:https://yubanet.com/regional/how-and-when-to-watch-the-total-lunar-eclipse/
During a solar eclipse, the moon casts two shadows. One is called the umbra; the other is called the penumbra.
image credit:https://stemcamp.ca/2018/05/06/space-sunday/image3-2/
The third type is an annular solar eclipse. An annular eclipse happens when the moon is farthest from Earth. Because the moon is farther away from Earth, it seems smaller. It does not block the entire view of the sun. The moon in front of the sun looks like a dark disk on top of a larger sun-colored disk. This creates an illusion of bright ring around the moon