Universe Guide

The Moon, Earth's Natural Satellite

What is a Moon?

In simplest terms, a moon is a celestial body that orbits a planet. The number of moons a planet can have varies from none in the case of Mercury and Venus to many tens such as in the case of Saturn and Jupiter. Our planet Earth has just one moon and that is what we see when we look up at night. Our moon is simply known as just The Moon. A moon can be the remnants of an collision between the planet and another planet such as in the case of our Moon or a captured asteroid such as those in orbit around Mars as the theory goes. At present, there is only one moon, Titan that has a thick atmosphere, other moons have relatively weak atmospheres such as Europa, Ganymede and Titania. ref:Futurism

We've known about our own Moon for thousands of years, its been in the sky since long before dinosaurs and in fact any living creature that has existed. However, the first non-Earth moon to be discovered were the moons of Jupiter when Galileo discovered the first Gallilean moons (Ganymede, Callisto, Io and Europa) as they are called orbiting Jupiter between 7th January and 13th March 1610. They're still be discovered, a moon in orbit round Neptune was discovered in 2013. Although a more recent one was discovered orbiting the kuiper belt object MakeMake. ref Wikipedia.

Extrasolar Moons / Exomoon

Moons aren't limited to only existing in our solar system. Exomoon is the shortened name for Extrasolar Moons. There's nothing to say that our solar system should be the only one whose planets have moons. It is believed that the planet 1SWASP J140747.93-394542.6 b has a possible exomoon in orbit round the planet. The planet and star is in the constellation of Centaurus in the southern hemisphere. Don't go looking for it with a telescope, you won't see the planet or the moon. Wikipedia.

Exomoons have been part of the science fiction narrative for a long time, anyone remember Moon of Endor from the end of the third Star Wars film, Star Wars VI - Return of the Jedi where the Rebels led by Han Solo carry out an attack to destroy the shield generator for the Death Star. The planet Endor is a giant gas planet which the Moon orbits. The Death Star is still tiny in comparison to the Moon of Endor. In recent times, in Avatar, the lush planet where all the adventures take place is a moon.

The Moon

The Moon that orbits the Earth is simply known as The Moon because for many centuries, it was the only moon that we were aware of and could see. The Moon is believed to have been created soon after the Earth was born. A planetoid called Theia smashed into the Earth and the debris flew off into space and eventually clumped together and became the Moon as we know it. The video I found on Youtube shows how sped up the Moon would have been created. The music is from World of Warcraft.

Video of the creation of the Moon

The Moon as you can see form the picture below is pock-marked, thousands of craters have been formed, some during the creation and some over time. The Moon has been a barrier, protecting the Earth from attacks from meteors that could have created a mass extinction

The Moon

The Moon remains the only celestial body that humans have journeyed to an landed as part of the Apollo space program. The first person to step foot on the Moon was Neil Armstrong who stepped foot on July 24, 1969 with Buzz Aldrin. They landed on the dark side of the Moon. The Moon does rotate but does so ever so slowly that you only get to see one side of the Moon.

The Moon is moving away from the Earth at an incredibly slow speed of about 3.78 centimeters a year. 3. We only get eclipses because although the Sun is further away, it is relatively the same size in the sky as the Moon. Eventually, the Moon will not be able to block out the light from the Sun as it can do now.

The Moon has a gravitational pull on the tides on the planet, when the Moon is full, the tides directly in its path and those at the opposite side to the planet are highest.

Since the Lunar Landing Missions stopped with Apollo 17 in 1972, the only things that have been to the Moon has been satellites. There is now interest in getting a manned lunar base which will be a stepping stone to Mars and then further afield. The gravity on the Moon is a lot less than Earth so the escape velocity required to get off and propel into space is less than on Earth. The reason why its less is because the gravity on the Moon is lower because the object is smaller. There are conspiracy theorists who believe we never got to the Moon and they point out the risk involved, anomalies in pictures and cost being just some of the reasons why. The Moon has a large repository of materials that are not easily found on the Earth such as Helium3 which is a great fuel. There is no Oil or Coal on the Moon because to find those, they would have needed to be have been an atmosphere and life to have existed and then turn into fossil fuels.

Religious Calendars

Whilst the Christian Calendar uses a Solar Orbit to determine the date, they still use a Lunar Calendar to work out when Easter Sunday will fall on. Easter Sunday is the first Sunday after a full Moon after the Spring Equinox, (March 21st). Unlike Christmas, Easter moves according to the Sun because when Jesus was crucified, the Jewish festival of Passover was taking place and it was deemed by The Council of Nicaea to use that as a framework for when Easter is to take place. 4

The Islamic Calendar or Al Hijra is based on the lunar calendar compared to the Gregorian Calendar that the Christian world use. The Gregorian Calendar is based on an orbit round the Sun, 365 days. The majority of the world uses the Gregorian calendar but some Islamic Countries such as Saudi Arabia use Al Hijra as their calendar. The first day of the new month is the first night on which the first crescent after a new moon is spotted. It still has 12 months but each month is 29.5 days giving a total of 354 days. To even out the months as you can't have .5 days, even months are 29 days and odd months are 30 days. Leap years in the lunar calendar are those in which dividing the year number by 30 gives remainder 2, 5, 7, 10, 13, 16, 18, 21, 24, 26 or 29. The Leap Day is added to Zul Hijja, the twelfth month of the year. 5.

The Moon Facts and Figures

Moon is one of the many natural planetary satellite moons of the planet Earth. The moon was discovered in Unknown by Known by the Ancients. The mass of the object is 73,476,730,924,573,500,000,000 kg. The equatorial circumference of the Moon is 10,917.0 km. The semi-major axis of the orbit around its planet is 384,400 km. The density of the Moon is 3.344 g/cm3. The orbit circumference, that is the total journey round the planet is 2,413,402.16 km.

The average orbit velocity/speed of Moon is 3,680.5 km/h. The Orbit Eccentricity is 0.0554, that is how much the orbit deviates from a circle, between 0 and 1. The Orbit Inclination is 5.16 degrees, that is how much the orbit deviates from a circle, between 0 and 1. The average orbit mean radius of Moon is 1737.5 km. The circumference of the Moon at the equator is 10,917.0 km. The volume of Moon at the equator is 21,971,669,064 km3. The surface area of the object is 37,936,694.79 km2.

The escape velocity, the speed which is need to break free is 8,552 km/h. The surface gravity of Moon is 1.624 m/s2 compared to Earth which for purpose of this site is 1. The sidereel rotation period, the time it takes for the Moon to rotate once is 27.322 Earth days. More information and the source for the Moon can be found at N.A.S.A.

Colours of the Moon

The actual colour of the Moon is a boring grey as seen in pictures taken in outer space. However due to our atmosphere, the Moon can appear as yellow or a blood red colour.

What is a Yellow Moon?

The Moon will appear as a Yellow Moon when light from The Sun is reflected off it at night.

Yellow Moon

What is a Grey Moon?

The moon's natural colour is a grey and this colour is best seen when the Moon appears in the morning or early evening when the Sun is still out. When you land on the Moon, this will be colour you will see.

What is a Blood Red Moon?

When the Earth Eclipses the Moon, the colour of the Moon will become a reddish colour. As it is red, there have been so called Prophets who have been announcing the end of the World. Well, there was a Blood Red Moon on the 28th September 2015 and we are still here. These so-called Prophets are nothing more than attention seekers and should be treated as just that.

What is a Blue Moon?

A Blue Moon is just a saying, it refers to when there are two full moons in a given solar calendar month. A solar calendar month can range from 28 days (February) up to 31 days such as December. For a month to have a blue moon, the first full moon of the year would be at the beginning of the month and the second at the end. A month could never have a blue moon when the first full moon is on or after 4th of the month. In the children's film, the Smurfs, the little creatures set out to create a blue moon to return back to their home.

What is a Supermoon?

The Moon as it orbits the Earth doesn't keep an equal distance from the Earth throughout. It can appear larger than normal and that's when it is referred to as a Supermoon. In the early days of the Earth, talking billions of years ago, the Moon was much closer than it was today and the Moon was much bigger in the sky. Although the Moon is moving away from us at a calculated 3cm a year, we will continue to have Supermoons for a while yet. A Supermoon can coincide with a Blood Red Moon which it did on the 28th September 2015.

What is the Dark Side of the Moon?

When you look at the Moon, you only see one side. The reason for this is because the Moon rotates on its axis at the same speed as it orbits round the Earth. When Apollo 11 carrying Neil Armstrong, Buzz Aldrin and Michael Collins to the Moon, they landed on the far side of the Moon which we don't see. Communication back was from the orbiting craft that would take them back to Earth.

First Moonbase

Having a base on the moon is future target of space agencies around the world. The only nation that has got to the moon and landed on it was the Americans with astronaut Neil Armstrong. Neil Armstrong landed on the moon on July 20th 1969 and there has been subsequent missions to the Moon up and until 1972 when Apollo 17 with Eugene Cernan was the last man on the moon. Since that time, no one's been back apart from satellites.

There is now a new race amongst the major nations of United States, Russia, China and India to put a base on the moon. They hope that the base will be a stepping stone to further afield such as Mars. To take off from the Moon requires less fuel than taking off from the Earth because the Earth has greater gravity.

The most famous fictional moonbase has to be Moonbase Alpha from the television series Space 1999 where a nuclear explosion on the moon caused it to go out of orbit and fly off into space. The moon flying off into space is not possible. The moon is moving away from the Earth extremely slowly but its not going to happen anytime soon, not for at least a billion years when by then the Sun will have expanded and life will have gone.

What if we didn't have the Moon?

The Moon is a stabalising factor for the planet, not just for calendars and people. If the moon wasn't here, our planet would wobble as it orbited the sun. If we didn't have the moon, our tides would always be the same, we wouldn't notice any change unless they were caused by the Sun but that doesn't do much. The nights would be darker as they'd be no moon to light up the sky. They'd be no eclipses because they'd be nothing to block the Sun.

Days on Earth would be shorter than they are now, they'd be eight hours in length instead of twenty four. The moon has the effect of slowing the Earth's rotational speed. We'd have thousand day years rather than what we have now. As the Moon moves away, our days will get shorter but again that is far far into the future.

The moon causes our planet not to tilt too much so if we didn't have it, the moon would be tilting erratically as we orbit the Sun. Our planet is titled at about 23 degrees caused by a catastrophic event early in the life but our tilt would be worst if there was no Moon.

Related Pages of Interest :-

Comments and Questions

There's no register feature and no need to give an email address if you don't need to. All messages will be reviewed before being displayed. Comments may be merged or altered slightly such as if an email address is given in the main body of the comment.

You can decline to give a name which if that is the case, the comment will be attributed to a random star. A name is preferred even if its a random made up one by yourself.

This website is using cookies. More info. That's Fine