The moon has been viewed in awe and wonder for thousands of years. Throughout history people from many cultures thought that it was everything from a mythological god to a tool of the gods.
Stories, songs, poetry, books, and films have been created about the moon and it wasn’t all that long ago that people thought that there were living creatures that had homes and lives on the moon.
No one ever gave the moon a real name because they didn’t think that there were any planets that had a moon (or moons). Now, we call all of the satellites orbiting a planet, their moons.
It’s thanks to the moon that we have a climate that’s stable, a tidal rhythm that has helped life to thrive, and is one of the main tools to guide humans during travel.
The Basics about the Moon:
- Distance from the Earth: Around 239,000 mi.
- Year (time to orbit the Earth): About 27 Earth days.
- Day: About 27 Earth days.
- Min temperature: -387 degrees F.
- Max temperature: 253 degrees F.
The moon is the brightest object in our night sky and allows our Earth to be livable by moderating the wobble of Earth on its axis.
It’s believe that the moon was created when there was a collision by a huge object with early Earth. Scientists think that the object had to be around the size of the planet Mars and when it collided, it took out big chunks from Earth that eventually formed together due to Earth’s gravitational pull.
Although it was in a molten state for millions of years, the “magma ocean” crystallized and the less-dense rocks came to the surface and formed the crust of the moon.
Our moon is the fifth largest moon of all of the 190+ that are orbiting the planets within our solar system.
The moon has three parts to it: a core, a mantle, and a crust. It’s important to know what the moon is made up of to understand the features.
The core of the moon is smaller than that of the cores of other terrestrial bodies. It’s believed to be solid and iron-rich, and is around 149 mi/240 km in radius. It’s surrounded by a liquid iron shell that is around 56 mi/90 km thick. A layer that is partially molten surrounds the iron core and is around 93 mi/150 km thick.
The moon’s mantle is from the top of the layer that is partially molten to the bottom of the crust of the moon. It’s made up of mostly minerals such as olivine and pyroxene, and they are made up of magnesium, iron, silicon, and oxygen atoms.
The crust is around 43 mi/70 km thick on the near-side of the moon’s hemisphere and 93 mi/150 km thick on the far-side. The crust consists of oxygen, silicon, magnesium, iron, calcium, and aluminum, with other amounts of titanium, thorium, potassium, and hydrogen.
At one time in the moon’s history it had active volcanoes but they haven’t erupted in millions of years and are all dormant.
There is only a minor atmosphere on the moon, and it is so sparse that it can’t slow down or stop any of the meteoroids, asteroids, or comets that strike the surface. For this reason, the moon’s surface has an incredible number of craters. The Tycho Crater is over 52 mi/85 km wide.
These impacts have continued over billions of years and have ground up the surface of the moon into pieces that are as large as boulders to fine powder. Almost the entire surface of the moon is covered in a charcoal-gray powdery dust and rocks that are called the “lunar regolith.” Beneath the fractured bedrock area is a region called the “megaregolith.”
The dusty powder that is on the moon was thought to be similar to the dust on Earth. However, when the astronauts spent time on moon’s surface they discovered that they had cuts and slits in their spacesuits.
They couldn’t explain them until scientists looked at the moon dust under a microscope and discovered that they looked like sharp pieces of miniature glass.
Without the benefit of erosion and wind like we have on Earth, the tiny particles of dust had sharp edges and it was the dust that was collecting on the spacesuits that was causing the slices as they moved in them.
The surface of the moon has lighter areas that are called the highlands. It also has darker features that are referred to as “maria,” which is Latin for seas.
These are impact basins that were lava filled around 4.2-1.2 billion years ago. Both the dark and light areas are made up of different compositions and show how the moon’s early crust might have risen and crystallized from the magma ocean.
The craters may be billions of years old and scientists study them to get an idea of the history of impacts that the moon experienced. This history can tell them a lot about impacts from other bodies in the inner solar system.
The surface of the moon also has some of the equipment that the astronauts left, including an American flag, a camera, and medallions to honor the U.S. and Soviet astronauts that were lost in the quest to explore space.
Gravity on the moon is one-sixth of that on Earth and if you ever watched the videos of the astronauts on the moon you would see them bouncing across the surface.
Is There Water on the Moon?
The first satellite and spacewalk explorations found what they thought was a dry and barren landscape on the moon. However, in 2008, the Indian Chandrayaan-1 space mission detected hydroxyl molecules across the surface of the moon and at a concentration at the moon’s poles.
Additional missions including the Lunar Prospector, LCROSS, and the Lunar Reconnaissance Orbiter have exposed that the surface of the moon has a global hydration and that there are concentrations of water ice in the lunar pole areas that are permanently in shadows.
The Man in The Moon:
The moon and the Earth are tidally-locked, so that the rotations are in sync and that’s why we only see one side of the moon all of the time. Anyone that has looked up at the night sky may recognize the face that everyone calls the “man in the moon.” This is an illusion of a human face and it always faces the Earth.
The moon is in a synchronous orbit around the Earth, which means that it makes one rotation each time that it circles Earth. Scientists don’t know why the moon settled into the orbit but it suggests that the face of the man in the moon is just a mere coincidence.
However, a new study conducted by a professor of planetary science, Oded Aharonson, at the California Institute of Technology in Pasadena, California indicates that the moon once turned on its axis faster when it was younger.
They found that the rate that the moon began to slow before it became tidally-locked into its current orbit explains why this particular side faces the Earth. The explanation involves the fact that although we might think the moon looks round, it’s actually more elongated, kind of like an American football.
Over 4 billion years ago the moon was forming and while it was still mostly molten, Earth’s gravity caused it to stretch. Once the moon started to cool it maintained this oblong shape and the man in the moon is seen on one of the ends of the elongation.
The moon’s rotation slowed over time due to the gravity of Earth tugging on it. The tidal forces of the tugging also created bulges that are on the side that faces Earth. The bulge churned the interior of the moon until it started to contract and expand and the bulge’s position changed.
The internal friction stopped the spinning of the moon until its rotation rate matched its rate of revolution and it became locked into the current orbit.
Scientists analyzed the moon’s physics by figuring out the rate that the moon slowed down and how it determined which side of the moon faces the Earth. The research team used computer simulations to examine the odds of this occurring.
Does the Moon ring like a Bell?
The Apollo lunar modules were constructed for the purpose of landing the astronauts on the moon’s surface.
However, after the LM’s returned the astronauts to the command module NASA decided to use the spacecraft for a scientific experiment. They directed the lunar modules so that they would have a controlled crash into the moon.
The crash created moonquakes and the scientists measured the vibrations as they moved through the moon. Astoundingly, they found that the vibrations sounded like they were ringing like a bell.
The seismic experiments were to try to find out about the internal structure of the moon, measure how long the vibrations lasted and how powerful they were. Measuring how large the waves would get was a method to figure out what the moon was made up of.
Part of the Apollo Lunar Surface Experiment Packages that had been set up by the astronauts on Apollos 12, 14, 15, and 16 included remote seismic stations. Different variations of them were left on Apollos 11 and 17.
All of these remote technologies measured all types of seismic activity on the moon. Any data was transmitted back to Earth-stations where the signals were magnified by 10 million for scientific interpretation.
Something strange happened on Apollo 12. After astronauts Pete Conrad and Al Bean had landed at the Ocean of Storms on Nov. 14, 1969, they then returned to the command module and sent the lunar module heading back to the moon.
It had an impact that was forty miles away from the Apollo 12 landing site and hit with the force of one ton of TNT. The shockwave built up and peaked in only eight minutes, but it took an hour to completely dissipate.
A similar occurrence happened with Apollo 13 when they sent the lunar module 85 miles from the seismic equipment left by Apollo 12. It hit with a force of 11 ½ tons of TNT and the seismic impact peaked after only seven minutes and had shockwaves thirty times greater and four times longer than experienced by the Apollo 12 team.
Scientists were surprised at the duration of both of the impacts. The sound was so much like the ringing of a bell that scientists began to rethink what the moon might be made of. The answer was figured out later when they recognized that some moonquakes occur deep below the surface and some are thermal quakes caused by the sun thawing the frozen surface at each new lunar day.
Still others are created by an impact, and the last type is a moonquake that happens around tens of miles below the surface. In both cases, the lunar module created a moonquake of the last type and these are the most violent of all of the moonquakes.
On Earth, we have moisture that acts as a dampening effect for quakes. The moon doesn’t have that kind of moisture so there is nothing to deaden the vibrations. In the case of the moonquake, the vibrations just keep going back and forth through the solid stone and the “bell” sound are the shock waves going through the stone.
- The side of the moon that we see is called the near side, while the other side facing away from Earth is called the far side. However, people still refer to it as the “dark side” of the moon.
- The 1966 Luna Program by the Soviet Union was the first successful landing of an unmanned spacecraft on the surface of the moon.
- The far side of the moon looks very different from the near side due to a lack of ancient pools of solidified lava.
- The moon is very cold at night and extremely hot during the day.
- The “phases” of the moon are: New Moon, Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, Crescent, New Moon….
- A lunar eclipse happens when the Earth is between the sun and the moon.
- When an astronaut puts on a spacesuit it’s called “donning,” and removal of the spacesuit is called “doffing.”