# Moon

The Moon is the Earth's solitary natural satellite, roughly 384,000 km (239,000 mi) away. It has roughly 38,000,000 km$^2$ (15,000,000 sq mi) of surface area, and is not believed to harbor any life. The Moon is the only natural object in space outside the Earth that humans have landed on, but manned missions to the Moon ended in 1972. However, several organizations are working to get humans on the Moon again.
Did you know that you could fit every planet in the solar system (including Pluto) in between the earth and the moon?

## Understand
### History

The first spacecraft to land on the Moon was the Soviet Luna 2 on 13 September 1959, which had no passengers, and it simply crashed on the Moon while taking pictures. The Soviet Luna 9 was the first spacecraft to soft land (meaning that it landed on the Moon without crashing) on 3 February 1966, and Luna 10 was the first to orbit the Moon on 3 April 1966. None of the Soviet Luna program spacecraft had crews.
The United States started the Apollo program in 1967, after President John F. Kennedy made an ambitious plan in 1961 to send people to the Moon by the end of the decade - in part to distract from the Soviets beating the U.S. to the punch on virtually every space "first" up to that point. Apollo 8 was the first mission to orbit the Moon bringing famous images to millions of households in time for Christmas 1968. Then on 21 July 1969, Apollo 11 brought Neil Armstrong to become the first person to set foot on the Moon, followed 20 minutes later by Edwin "Buzz" Aldrin, fulfilling Kennedy's plan. They planted a U.S. flag and collected some rock and soil samples. All subsequent Apollo missions except for Apollo 13 successfully landed on the Moon, and all of them were crewed. Apollo 13 failed to land, and it became the best-known space accident where the astronauts actually survived. The Apollo program ended in 1972, and the last mission was Apollo 17. Meanwhile, the Soviets would end their Luna program with Luna 24 in 1976. Both the Soviet unmanned missions and the American manned missions brought back rock samples and the Americans in particular gave them to entities all around the globe as gestures of goodwill. The only other nation to return samples of lunar material to earth is China, doing so in late 2020.
Only 24 lucky souls$^{[deadlink]}$ have ever flown to the Moon during nine American missions from 1968 to 1972. Of those 24, only 12 of them landed and walked on the Moon. All 24 were men, so the status of "first woman on the Moon" is open for the taking if you have the money and the drive. All visitors to the moon to date have been from the U.S.A., so if you're from a different country, the title of being the first from your country to land on the moon is also available to you.
Due to the fact that the Moon takes the same time to rotate around its own axis as it does to revolve around the Earth, it is always the same side of the Moon that faces Earth. On 7 October 1959, the Soviet Luna 3 became the first mission to send back images of the far side of the Moon (the side facing away from Earth). All humans who have landed on the Moon have only explored the near side, with the far side still unvisited by humans, so the status of being the first human to visit the far side of the moon is up for the taking too. On 3 January 2019, China's Chang'e 4 made the first successful soft landing on the far side of the moon, albeit unmanned.
On 23 August 2023, India's unmanned Chandrayaan-3 mission made the first successful landing near the south pole of the moon, days after Russia's Luna 25 mission failed in its attempt and crashed. This made India only the fourth country to successfully land an object on the moon, after the Soviet Union, the United States and China.

### Landscape

The lunar landscape has features called maria (Latin for "seas", pron. MAH-ree-uh; singular mare pron. MAH-ray) which are large darker areas that were once mistaken by earthly observers for "lakes" and highlands. Besides that, there are a lot of impact craters as there is next to no erosion that would reduce their prominence over time. Also, the Moon has no atmosphere, so smaller asteroids will not burn up because of heat created by friction with air. Close to the poles there are "mountains of eternal sunshine" and "valleys of eternal darkness" which occupy positions that are either permanently bathed in sunlight or permanently dark. Potential future missions might use them for a reliable source of solar energy or reliable cool storage respectively and it is hoped that ice (for use as drinking water or fuel) might be found in a relatively easy-to-access way in some of the colder spots.

### Climate

Because the Moon has no atmosphere and rotates very slowly, it experiences extreme temperature variations depending on whether or not the sun is out. The temperatures range from 127 °C (261 °F) in the Lunar days to −173 °C (−279 °F) in the Lunar nights. There are no seasons on the Moon, because the Moon's axis of rotation only tilts by about 1.5 degrees, compared to the Earth's tilt of about 23.5 degrees. Apollo astronauts' ships and spacesuits were well insulated and had internal temperature regulation systems, and so will the ships and spacesuits of your mission. In the vacuum of space it is much easier to gain heat than to get rid of it, as the only method of heat transfer available (radiative) is much less efficient than convective heat transfer.

## Get in

The Moon has had no human visitors since the end of the Apollo program in 1972. Unmanned missions ended in 1976 (Soviet Union, Luna 24 probe), only resuming at the end of 2013 (China, Yutu ("Jade Rabbit") rover). As a result, only the United States has successfully landed humans on the moon. The only other countries to have successfully landed objects on the moon are the Soviet Union, China and India.
Several space agencies have proposed manned missions to the Lunar surface in the 2020s.
If you cannot get into space, you can still see the Moon from Earth; see Astronomy.

### Space Adventures

The space tourism company Space Adventures is planning to take some people around the Moon. The plan is to first spend about ten days at the International Space Station, then a six-day journey to the moon and back. The spacecraft won't land on the Moon, instead simply looping around it and coming back to Earth. It will fly within "a few hundred kilometers" of the Moon. The time of departure and the price is still undetermined, but the price will probably be in the hundreds of millions of dollars range. Contact them if you're interested and you have the dough.

### To the surface

As of June 2019, there are no serious plans for tourism on the surface of the Moon. All proposed missions to the Lunar surface are for professional astronauts only, and are not the type of thing where anyone could pay money to go to the Moon. Some private companies have proposed tourist trips to the lunar surface, but none of these have started serious development.
The U.S. is planning the mostly crewed Artemis program, although Artemis 1 will not be crewed, and Artemis 2 will just be a flyby. Artemis 3 is expected to launch in no earlier than September of 2026, and all Artemis missions from Artemis 3 will be landings and colonization. NASA also planned to build a "Gateway" in Lunar Orbit where astronauts can prepare for the landing and the trip back, which will launch no earlier than 2025.
Russia, Japan and China have all proposed crewed lunar landings in the 2030s.

## Fees and permits

The Outer Space Treaty, which more than 100 countries have signed, states that "the activities of non-governmental entities in outer space, including the Moon and other celestial bodies, shall require authorization and continuing supervision by the appropriate State Party to the Treaty". Contact your government to ask what kind of authorization, if any, is required. In the 21st century, some countries have introduced very generous legislation for "space mining" that apply to any company headquartered in that jurisdiction and are often an attempt by countries not considered "traditional" spacefaring powers to get "a piece of the pie".

## Get around
### By aircraft

Conventional aircraft are useless on the Moon since there is no atmosphere to generate the aerodynamic lift they require to fly. Internal combustion engines have to carry around both fuel and oxidizer (air or a substitute) and there are issues with cooling in a near perfect vacuum. When you orbit the Moon, you will be in a lunar module which will give you living space and can fly without surrounding air. The lunar module can also land on the Moon.

### By lunar rover

The primary method of transportation has been battery-powered lunar rovers, commonly known as "moon buggies", formally as Lunar Roving Vehicles (LRVs). Some lunar rovers can have passengers, such as the ones used by the last three Apollo missions. They were carried by the lunar module and never went faster than about 10 km/h (6 mph). They are still stranded at Mons Hadley, the Descartes Highland and the Taurus-Littrow valley. Whether they still are in any workable condition or can be brought into one with limited repairs is not known.

### By foot

Gravity on the Moon's surface is only one-sixth of that on the Earth, which compensates in part for having to wear a bulky pressurized spacesuit. Most of the Apollo astronauts have "walked" in a rather peculiar half-jumping fashion that is only possible due to the lower gravity and appears to be the best form of locomotion due to the somewhat motorically limiting nature of a space-suit. You will have to learn a new way to walk, as when the Apollo astronauts tried to walk like they do on Earth, they flew up into the air and fell. Depending on the design of your space suit, falling (particularly falling backwards) can be dangerous as the life support equipment is often contained in a "rucksack" on the back of the space suit.

### Future

Due to several considerations (lack of air, low gravity, no energy resources apart from sunlight) magnetic levitation railways have been proposed as a possible method of transportation once a moonbase (or several) is established. However, the plans for moonbases that exist are not detailed enough to include such features.

### Maps

NASA's Moon Trek mapping application has extensive information, images, and tools to help you plan a mission or just learn about the Moon. Google Moon also provides a vaguely decent map of the Moon, with information and labels for past landing sites.

## See

* Luna 2, Exact location unknown (near Aristides, Archimedes, and Autolycus craters). The first man-made object to reach the Moon. Luna 2 was crashed onto the Moon, so all you'll see would be pieces. (updated Jun 2019)
* Earth. Visible from only the near side of the Moon. It looks like what the Moon looks like on Earth; there are full earths, crescent earths, and new earths! However, contrary to popular misconceptions, if you don't move you will only ever see the Earth in the same place and no such thing as an "earthrise". But if you are orbiting the Moon, you'll see the Earth rise and set when you cross the border between the Near and Far sides of the Moon. The landscape of Earth changes, as clouds drift around – and as the Earth rotates. (updated Jun 2019)
* Dark Side of the Moon. Visit the part of the Moon that is not visible from the Earth. However, it is said "there is no dark side in the Moon, really. As a matter of fact it's all dark". The real truth is that any spot (except near the poles) is lit half the time: the same time a spot facing Earth is dark. During a full moon on Earth the entire Dark Side is dark, and during a new moon all of it is lit. We have satellite images, but only the Apollo astronauts who circled the Moon have ever seen it with their own eyes. Only one mission has ever landed or attempted to land there, the 2019 unmanned Chinese mission Chang'e 4, which required a relay satellite to be launched first to keep the contact with Earth. And, for some strange reason, there are much fewer maria (in case you don't remember it, the big dark areas) on the Dark Side of the Moon. (updated Jun 2019)
* Solar eclipse. The astronauts of Apollo 12 had seen and photographed it. When you see a solar eclipse on the Earth, it's because the Moon is directly in front of the Sun. But on the Moon, it's because the Earth is directly in front of the Sun. (updated Jun 2019)
* Lunar south pole. The south pole is where most of the Moon's water is believed to be, mostly in the form of ice. The first successful landing near the south pole was made by India's Chandrayaan-3 mission in 2023. (updated Aug 2023)

### Apollo landing sites

* Mare Tranquillitatis (Apollo 11 Landing Site), The Sea of Tranquility (near Sabine and Ritter craters). The location of the first manned Moon landing. On July 21, 1969, NASA astronauts Neil A. Armstrong and Edwin "Buzz" E. Aldrin set foot on the Moon to become the first humans to ever touch another celestial body. Look for the American flag that was knocked over by the exhaust of the departing ascent stage of Eagle, the lunar lander, and the television camera left behind. Try not to disturb the footprints in the soil — due to the lack of an atmosphere and erosion, the footprints will likely remain as they are, completely undisturbed, for millions of years to come. Lastly, try to find the plaque on the remaining descent stage of the lunar lander, which contains the names and signatures of the crew of Apollo 11, then–U.S. President Richard Nixon, and a message commemorating the location as being where the first landing took place. (updated Jun 2019)
* Oceanus Procellarum (Apollo 12 Landing Site) (southeast of the Montes Riphaeus). The location of the second manned Moon landing, Oceanus Procellarum (the Ocean of Storms) is also the location of the Surveyor 3 unmanned space probe, the only space probe to have landed on another planet and had parts of it returned to the Earth. This is the only mare to be called an ocean, because of its enormous size covering over 10 percent of the Moon's total area. To be exact, the Apollo 12 landed in the Mare Cognitus which is inside the Oceanus Procellarum. Like all other Apollo missions, Apollo 12 left a plaque, so try to find it! (updated Jun 2019)
* Fra Mauro Highlands (Apollo 14 Landing Site). The location of the third manned Moon landing, the Fra Mauro Highlands contain the massive, 80-km-diameter crater of the same name within. This was the intended landing site for Apollo 13, but since it didn't land, Apollo 14 landed here. Also the location of Alan Shepard's impromptu golf excursion, if you're one for putting. (updated Jun 2019)
* Hadley Rille (Apollo 15 Landing Site). The location of the fourth manned Moon landing, the Hadley Rille is located within an expanse of the Mare Imbrium (Sea of Rains) known as the Palus Putredinus (Marsh of Decay). A rille is a geographical feature on the Moon which looks like canyons or canals. The location of the first Lunar Roving Vehicle (the Lunar Rover for short) is here. Also the location of the Fallen Astronaut, a small plaque and aluminum sculpture, placed face down in the regolith by the crew of Apollo 15, that commemorates the 8 American astronauts and 6 Soviet cosmonauts who had lost their lives up to late July/August 1971. (updated Jun 2019)
* Descartes Highlands (Apollo 16 Landing Site). The location of the fifth manned Moon landing and the second of the three Lunar Roving Vehicles. Look for large rocks to take home; this was the site where the largest rock returned by the Apollo missions, nicknamed "Big Muley", was found. Also, look for "House Rock", a massive formation taller than a four-story building, in the vicinity of the landing site. Lastly, look for the family photo of astronaut Charlie Duke that he left behind on the surface. (updated Jun 2019)
* Taurus-Littrow (Apollo 17 Landing Site). The location of the sixth and (thus far) final manned Moon landing, Taurus-Littrow is a massive valley located in the Mare Serenitatis (Sea of Serenity), and named for the nearby Taurus range of lunar peaks and the Littrow crater. Look for the famed orange volcanic soil that was discovered on the Moon here, and the third and final Lunar Roving Vehicle. Also, look for "TDC" etched into the lunar regolith by Gene Cernan in honor of his then-nine-year-old daughter, Tracy. As with everything else on the Moon, this will likely last for millions of years due to the lack of erosion and atmosphere. (updated Jun 2019)

## Do

* Think of something profound to say on your arrival. Things that the Apollo astronauts said on their arrival includes:
** "That's one small step for [a] man, one giant leap for mankind." — Neil Armstrong, Apollo 11
** "Whoopie! Man, that may have been a small one for Neil, but that's a long one for me." — Pete Conrad, Apollo 12. Conrad was significantly shorter than Neil Armstrong.
** "And it's been a long way, but we're here." — Alan Shepard, Apollo 14
** "As I stand out here in the wonders of the unknown at Hadley, I sort of realize there's a fundamental truth to our nature. Man must explore. And this is exploration at its greatest." — David Scott, Apollo 15
** "There you are: Mysterious and Unknown Descartes. Highland plains. Apollo 16 is gonna change your image. I'm sure glad they got ol' Brer Rabbit, here, back in the briar patch where he belongs." — John Young, Apollo 16
** "Hey, who's been tracking up my Lunar surface?" — Harrison Schmitt, Apollo 17, the first and only professional scientist sent to the Moon on an Apollo mission
* Rock collecting is the most obvious hobby, and it's easy to do since the Moon is one giant rock. Dust collecting is also a favorite among tourists.
* Plant your nation's flag on the lunar surface. Be sure to take plenty of photographs to show to the folks back home.
* Play golf. There are no established golf courses available, but the Moon does provide you with an excellent opportunity to practice your sand trap shots. Apollo astronauts had played golf on the Moon, really. Another cool thing is, golf balls would fly 6 times as far as they do on Earth, because of the lower gravity.
* The moonwalk. Could be tricky in a spacesuit, but there is no better place to do it.
* Have fun jumping around with the low gravity. You can jump 2 m (6.6 ft) high!
* Take lots of pictures. Make sure you use a specially designed camera that can be operated with the bulky gloves that are usually part of a space-suit.
* Astronomy on the Moon is most likely great. While you can't see any stars in broad daylight on the Moon either, the lack of atmosphere means no twinkling and no obstructions and given that there is no artificial light or radio interference from Earth, there have been serious proposals to establish an observatory on the back side of the Moon.

## Buy

There are no shops of any sort on the Moon, so all supplies must be brought. Moon rocks would be a nice souvenir to take home, but if tourism ever gets common there might have to be regulation à la leave no trace camping.

## Eat

While ancient legends on Earth report the reflection of the Moon to appear as a wheel of green cheese, its soil is not edible. There are no restaurants or shops available on the Moon, no food service amenities and no moon pies. Take all the food you need with you. Astronaut food has been called incredibly bland, but then again so has airline food.

## Drink

    "Moon River, wider than a mile, I'm crossing you in style some day. Oh, dream maker, you heart breaker..."
There is some amount of water across much of the surface of the Moon in the form of ice, but it is unclear how easy it is to access.
Thus far, all manned missions have brought their needed water with them. The modern International Space Station has some water reclamation capability, but missions in the Apollo era did not. Due to its weight, water is expensive and costly to transport but there is no viable alternative. Any long term stay will have to rely on recycling water in some fashion.

## Sleep

The next phase of lunar exploration will probably involve the construction of permanent manned bases in the Moon's polar regions. In the meantime accommodation is limited to what you bring. The lunar landers of the Apollo program have all been equipped to be used for sleeping, so chances are that you'll be sleeping in whatever you landed in.
Because of the sunlight, there may be some difficulties going to bed. Apollo astronauts slept and woke on command, using the time zone of their departure place.

## Stay safe

The Moon is subject to international law under the Outer Space Treaty and the Moon Treaty (although none of the major space-faring nations have ratified the latter, so its applicability is questionable). Among other things, the Outer Space Treaty puts the responsibility of any man-made object with the state that launched it (a malfunctioning Soviet satellite named Kosmos 954 spread radioactive material all over northern Canada in 1978, for which the Soviet government eventually paid CAD3 million), so check with the laws of the government where you will be launched from.
Space however is generally inhospitable and this will become all too apparent once you leave the comforts of Earth. In addition to the obvious problems of freezing cold temperatures and the lack of a breathable atmosphere, in order to stay alive you will have to take precautions against:
* Solar storms and cosmic rays (there is no magnetic field to deflect these high energy particles)
* Meteor impacts (there is no atmosphere to burn them before they impact the surface)
Bear in mind that the temperatures also go well below freezing if you are not in direct sunlight. If you are, you run the risk of skin cancer. Luckily, spacesuits can protect you from extreme temperatures and will give you air.

## Stay healthy

There are no hospitals or emergency medical facilities on the Moon and communication with emergency services on the Earth are slow. Oxygen deficiency may also be a problem. However, there are no native infectious diseases on the Moon and neither are there pests, such as mosquitoes or tour touts. Make sure you maintain strict hygiene with everything you bring to keep it that way. If any medical emergency does arise, the nearest substantial healthcare provider is at least 3 days away – and you have to go to them, they aren't coming to you.

## Connect

Communications back to Earth, as deployed for the Apollo missions, are primitive but usable. Slow-scan television (SSTV) lunar transmissions must share communication bandwidth with telemetry data. Image data from the five Lunar Orbiter spacecraft is transmitted to Earth stations "M" (Madrid, Spain), "W" (Woomera, Australia) and "G" (Goldstone, California) and logged to tape. As real-time conversions from SSTV format for live broadcast on Earth were little more than primitive screenshots, by the time that the July 21, 1969, moonwalk gets uploaded to YouTube substantial losses in image quality are visible.
Transmission from lunar rover via a Command Service Module in lunar orbit to Earth is infeasible for visitors to the lunar poles or the dark side of the Moon, as line-of-sight transmission to Earth is simply not available. A 2008 NASA proposal advocates lunar-orbiting satellites as a workaround but no system has been deployed. The Chinese Chang'e 4 mission, which has made the only soft landing on the far side of the Moon to date, uses a satellite orbiting around the Earth-Moon L$_2$ point to relay signals between its Yutu 2 lunar rover and Earth. If a lunar base on the remote side ever gets built (perhaps for astronomy?) there might be an incentive to transmit the signal via cable (preferably built from lunar material) to the near side and only then send it to earth via antenna. While this would be a lot more expensive and difficult than a relay satellite at the L$_2$ point, it would eliminate possible interference with astronomical observations and give an increased bandwidth.
A postmark exists for "United States on the Moon", a rare one-of-a-kind collector item. A matching pair of 8¢ stamps were issued by USPS with captions "United States in Space", "A decade of achievement". The mail pouch is stored under Apollo 15 commander David Scott's seat on the lunar rover, last seen around Hadley Rille on August 2, 1971. Be sure to send or bring back a few moondust-covered postcards as souvenirs.
Plans for establishing a 4G network by 2019 are in place. Yes, really! It's being launched in order to allow lunar exploration vehicles to communicate with each other, and to transmit HD video of the Moon's surface back to Earth.
No matter what happens, to communicate between the Moon and the Earth, you will always have a delay of about 3 seconds. That's because nothing can go faster than light, so the signals that you send will go for about 1.5 seconds until it gets to the Earth, and when Earth responds, the signal will go for another about 1.5 seconds until it gets back to the Moon.

## Go next

* Earth, how can you live without it? (for now)
* Space. Due to the lower gravity the Moon has been considered a good starting point for exploration beyond as the amount of fuel to get an amount of payload into orbit is lower than from Earth's surface.