The Moon is our constant companion and is easily found in the night sky. Since ancient times, humanity has relied upon the rhythms of nature’s cycles for guidance.
For instance, one calendar month can be measured between full moons. Unfortunately, the Moon’s phases and orbit can often be confusing, and its size changes depending on where Earth, sun, and Earth all fit together.
The Moon is one of Earth’s satellites, measuring 2,159 miles (3 475 kilometres). Although larger than Pluto, four other moons exist that outshone our own.
The Moon is more significant than one-fourth of Earth, at 27 percent; this ratio is significantly greater (1:4) than other moons and exerts considerable influence over Earth, potentially playing a part in creating life itself.
How Far Away Is The Moon From Earth?
The Moon is about 238,860 km (382,500 miles) from Earth. This is equivalent to 30 Earth diameters.
How Large Is The Moon Compared To Earth?
The diameter of the Moon is about one-fourth that of the Earth. Regarding surface area, about 1/16th of the Earth’s surface is covered by the Moon. The Moon’s mass is approximately 1.2% that of Earth.
When Is The Closest Time For The Moon To Earth?
Perigee is the point in the Moon’s orbit where it comes closest to Earth, often known as the “supermoon.” At perigee, approximately 224,000 miles separate Earth from its Moon; supermoons appear larger and brighter than their counterpart apogee (furthest point away from Earth).
It can be hard to distinguish between micro moon and supermoon lunar events just by looking at them, so the effects become more apparent when considering tides.
Full and new moon tides experience the most significant changes: spring tides are two inches higher for supermoons than regular spring tides.
In contrast, micro moon spring tides show minor variance due to gravity being stronger during perigee than apogee periods when closer to Earth; this phenomenon occurs because lunar gravitational pull increases at perigee periods while less so during apogee when farther away.
What Would Happen If A Moon Crashed Into Earth?
Based on analysis of lunar samples and the composition of the Earth and Moon, many scientists believe that our large Moon formed due to Earth colliding with another more minor planet similar to Mars; in a sense, it has come into collision with us before!
The Moon is not on a path toward colliding with Earth; it is slowly retreating at an average annual rate of 1.5 inches per annum.
The Moon provides many essential functions, including stabilising our orbital tilt, altering season changes, influencing tides, and aiding nocturnal animals with navigation.
If it were suddenly gone from our lives entirely, it would cause drastic environmental shifts that animals on Earth might struggle to adapt to; we do not yet observe such dramatic effects due to its gradual retreat.
An Earth and Moon collision would be devastating for all life on our planet. The asteroid responsible for the dinosaur extinction was approximately 12 km wide. In contrast, our Moon spans 3,550 km, or about 300 times more significant.
However, something known as the Roche limit enumerates how close large satellites such as the Moon may approach Earth without being torn apart by tidal forces.
At approximately 11,500 miles from Earth, gravitational forces would cause the Moon to disintegrate due to Earth’s gravitational pull, sending debris flying down onto our planet that may eventually warm it beyond the survival threshold.
Such an event may subsequently extinguish all life on Earth except some extremophiles that can thrive despite climate change.
How Did The Moon Form?
Origins of the Moon remain controversial; however, new evidence points towards it having formed through an impact that sent pieces of primitive Earth flying into space.
Scientists estimate the mass and size of an object believed to have made contact with Earth was likely equivalent to 10% of Earth’s mass and Mars’s size, respectively.
Researchers believe it happened approximately 95 million years after the formation of our solar system (circa 4.6 billion years old).
2015 research added further support to this theory, using simulations of planet orbits in an early solar system and newly discovered differences in the abundance of Tungsten-182 detected on Earth and the Moon.
There are other theories for the formation of the Moon. One such approach, known as the “large impact theory,” holds that Earth captured or fissioned from Venus and then stole back the Moon for itself.
What Is The Moon Made Of?
It is believed that the core of the Moon represents only 1-2% of its mass, measuring an estimated diameter of around 420 miles (680 kilometres). It is most likely made of iron but may contain considerable sulphur or other substances.
The Moon’s mantle measures approximately 825 miles (1,330 km) and comprises dense rocks rich in magnesium and iron.
Magma from within its depths has slowly seeped to the surface over billions of years, causing volcanic eruptions from four billion to three billion years.
The lunar crust measures 42 miles (70 kilometres). Due to several significant impacts that have befallen it over the years, much of its outermost part has been battered and broken up, providing access to intact material just beneath this fragmented area – about 6 miles (9.6 kilometres).
The Moon, like the four innermost planets in our solar system, is composed of rock. Like them, its surface is riddled with craters left from ancient impacts caused by asteroids striking its surface millions of years ago. However, they remain intact today due to no weather in this distant world,
The average composition by weight of the lunar surface is roughly 43% oxygen. Spacecraft orbiting the Moon have identified signs of water that may have come from deep underground sources and hundreds of pits that could house long-term explorers on its surface.
Lunar Reconnaissance Orbiter observations have revealed more water on slopes facing south on the Moon’s south pole;
However, scientists note this amount may be equivalent to what can be found in desert environments. A 2017 study suggests the interior may also contain pockets of liquid.
Does The Moon Have An Atmosphere?
A thin layer of dust, or even a footprint, can remain on the Moon for hundreds of years. Heat only stays near the surface with much of an atmospheric layer.
This causes temperatures to vary widely. On the dayside of the Moon, temperatures can reach as high as 273 degrees F. (134 Celsius).
How Does The Moon’s Orbit Around Earth And Cause Tides?
NASA Stats:
- Distance from Earth average: 384,400 km (238,855 miles)
- Perigee (closest approach to Earth): 225.700 miles (363.300 km)
- Apogee (farthest point from Earth): 252,000 miles (405 500 km).
- Orbit circumference: 1,499,618.58 miles (2,413,402 km)
- Mean orbit velocity: 2,287 mph (3,680.5 kph)
Tides are caused by the Moon’s gravitational pull on Earth and occur to some degree in lakes, the Earth’s atmosphere, and its crust.
Low tides occur when the water level decreases due to gravity and inertia. Since high waves form closer to the Moon, low tides occur between these two bumps of high and low tides.
Tidal braking, caused by the Moon, lengthens each day by taking on energy that Earth loses through heat loss and gradually increasing distance from it – increasing by about 1.5 inches yearly.
The gravitational force from the Moon could have played an essential role in making Earth habitable by moderating Earth’s axial wobble, leading to relatively stable climate conditions for billions of years in which life flourished.
This interaction has had profound repercussions for the Moon. According to a new study, Earth’s gravitational pull stretched it into its unique, deformed form early on.
What Is An Eclipse?
An eclipse occurs when the Sun, Earth, and Moon align in line, with the Earth standing between the Sun and Moon and casting its shadow across its face. Lunar eclipses can only take place during complete moon cycles.
Due to the Moon being in the shade during a lunar eclipse, its shadow may produce an orange or blood-red tint in the sky.
Solar eclipses occur when the Moon casts Earth’s shadow onto it as it travels between the Sun and Earth. They only happen during the new Moon.
Solar eclipses may be annular, total, or partial, depending on how much of the Moon’s shadow covers a specific location on Earth. Unfortunately, its footprint on our surface would never allow a total solar eclipse at any particular site.
Does The Moon Have Seasons?
Earth’s rotational axis is tilted by about 23.5° about an imaginary disk representing Earth’s orbital path around the sun.
The Northern and Southern Hemispheres are tilted slightly toward or away from the sun, depending on the season. This affects the amount of sunlight they receive.
The Moon does not experience seasons because its axis tilts only 1.5 degrees. Some areas are constantly lit by the sun, while others are permanently in shadow.
Early Observations Of Earth
Ancient Greek philosophers knew moonlight was created from sunlight reflected off an object orbiting Earth or a planet.
Ancient Greeks believed that dark regions on the Moon represented seas, while its brighter areas represented land. This belief led them to name these regions “maria,” Latin for oceans, and “terrae,” Latin for land. This idea continues today through words like “maria” or “terrae.”
Galileo Galilei was a Renaissance astronomer who first used a microscope to observe the Moon. In 1609, he reported its rough and mountainous surface – contrary to what was believed then.
Race to the Moon
In 1959, the Soviet Union launched the first spacecraft to reach the surface of the Moon and take photos from both sides. Both nations then conducted uncrewed missions during the Cold War to study its surface more thoroughly.
Early moon probes failed or were only partially successful. Yet, over time, these missions provided information about the surface and geology of the Moon.
Pioneer, Ranger, and Surveyor missions from the United States while Luna and Zond probes from Soviet Russia provided data.
In the 1960s and ’70s, the United States launched astronauts into orbit around and onto the surface of the Moon. Apollo 8 astronauts became the first to orbit it on December 24, 1968.
Apollo 11 was the inaugural surface mission to successfully land astronauts on the Moon in 1969, followed by five more successful missions (including Apollo 13, which didn’t quite make it there but returned safely home) since. To date, humans have only visited one extraterrestrial body – our Moon.
During their efforts, Apollo returned an estimated 842 lbs to Earth, which have since been studied. New uses have been discovered through technological improvements.
For instance, 2013 saw water detected in samples collected by Apollo 15, 16, and 17, which was previously thought to be highly unlikely given that previous analysis indicated these rocks were dry.
Soviet Russia continued its robotic lunar exploration throughout the 1960s and 70s. Luna 16 was the first robotic mission to successfully return lunar samples in September 1970 after multiple failed tasks.
Two months later, the Soviets unveiled Lunokhod 1, their inaugural robotic lunar vehicle. By 1973, Lunokhod 2 set an off-world driving distance record that stood for over 40 years before NASA’s Mars Opportunity rover, operating since 2014, overtook it.
Modern Missions
After NASA’s Apollo ended and an interlude lasting more than ten years had passed, the U.S. spacecraft returned to explore the Moon.
Since then, other space agencies such as Japan, the European Space Agency, China, India, and Israel have joined the race to reach the Moon.
So far, only China has successfully operated on its surface. At the same time, both landers sent by India and Israel crashed upon landing on it.
Russia, Japan, and the United Arab Emirates are currently discussing future lunar missions.
President Donald Trump directed NASA in 2019 to begin working toward returning humans to the Moon by 2025 through Artemis, NASA’s crewed exploration initiative powered by their heavy-lift rocket Space Launch System.
Artemis 1 was the inaugural mission in NASA’s Artemis Program and completed an unmanned orbit around and back of the Moon in 14 hours and 47 minutes (equivalent to 647 GMT).
Launched from Launch Complex 39B of Kennedy Space Center Florida on November 16, it splashed down in the Pacific Ocean at 12:40 pm EST on December 11 after covering over 1.4 million miles (2.3 million kilometres).
Water on the Moon
Before and after the Apollo and Luna missions brought samples, most believed the Moon’s surface was dry.
Chandrayaan-1 was the first mission to discover water on the Moon. It identified hydroxyl molecules spread across its surface and concentrated near its poles.
Subsequent missions, including Lunar Prospector and LCROSS missions and Lunar Reconnaissance Orbiter, have shown that global hydration exists on its surface.
However, pockets with high concentrations of frozen water may be near permanently shadowed regions near the lunar poles.
Scientists have also recently discovered that the lunar surface releases water when bombarded by micrometeoroids. A few centimetres thick layer of dry soil protects its surface; only large micrometeoroids can penetrate its defences and create craters when they strike;
Their shockwave is powerful enough to cause water-coated grains in the soil to release their holdback, with most going into outer space as a result of being released back into play.
NASA’s Stratospheric Observatory for Infrared Astronomy confirmed for the first time that water was present on the Moon for the first time in October 2020.
This evidence supports previous claims of water’s presence not just being isolated to cold, shadowed areas. Instead, it may exist all across its surface.
SOFIA identified H2O molecules in Clavius Crater on the Earth side as one of its most enormous visible craters on the lunar surface.
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