Evolution of the Moon

An artistic approach to science; objects are not to scale in dimension or time

Descriptions in bold were written by students at North High School, Denver
Additional text supplied by education specialists at the Lunar and Planetary Institute

About 4.5 billion years ago, two early solar system bodies began their existence.  Lava ruled the infant orbs.  Thus they formed what we know as the primordial Earth and Moon.

 

Timeline 1 As the rocky materials orbiting Earth accreted, the Moon (rising in the horizon) grew larger and hotter. Heat from accretion caused the outer surface, and perhaps more, of the Moon to melt, forming an ocean of magma.

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As time marched on, the Earth and Moon began to cool and a hard surface crust formed over both mysterious bodies.  Debris filled the early solar system and massive asteroids and comets crashed into the Earth and Moon with terrific cataclysmic force.

Timeline 2 From its formation until 3.8 billion years ago, an abundance of material remained in space and debris of all sizes constantly pummeled the Moon and all other planetary bodies. The impactors left their mark; huge impact basins such as Imbrium, Crisium, and Serenitatis, hundreds of miles across, occur where they struck the Moon.

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Chemical reactions continued on the Earth.  Water in vast quantities began to rule the planet, while the airless Moon continued its change.

Timeline 3 Although cooling, the Moon was still hot. Isolated pockets of hot mantle material slowly rose to the surface, melting at lower pressures. This magma poured out through cracks in the lunar surface — fissures — many of which were created by the earlier impacts. The magma flooded across the lowest regions on the lunar surface to fill the impact basins. Although impacts continued, they probably weren’t as frequent as depicted here, and they would have originated from a variety of directions.

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As early water began to cover most of the Earth’s surface, the Earth’s closest neighbor remained parched and dry.

Timeline 4 The magma cooled to cover portions of the Moon with dark basalt, making the “maria” or “seas” that we see today.  Although impacts continued, they probably weren’t as frequent as depicted here, and they would have originated from a variety of directions.

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The Earth experienced many evolutionary changes in its early existence.  The oceans began teaming with life, the land was introduced to its own residents.  These too underwent major changes along with the Earth’s atmosphere.  Earth succumbed to the great ice ages periodically as the ghostly Moon looked on.

Timeline 5 The Earth has changed tremendously in the last billion years, as the atmosphere filled with oxygen, diverse life evolved, and ice ages came and went.  Throughout that time, our Moon has been geologically inactive except for small meteoroids pummeling its surface, breaking the rocks and gradually adding to the layer of fine lunar dust — regolith — that covers the surface.

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Nothing in the universe slows down time, and change is an unwritten law of nature.  Behemoths of the animal kingdom no longer ruled the Earth, for a new life form began to flex its muscle and independence…the human race.  These new creatures once having left their caves, began to create substantial civilizations.  And yet, the Moon, like a bystander at a ball game, could only watch.

Timeline 6 The Mayan, Aztec, and other mesoamerican civilizations built pyramids and observatories to note the positions of celestial objects; in addition to the Sun and Venus, they particularly noted the changing appearance and position of the Moon.

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Modern civilization now blankets the Earth, while the desolate Moon remains as it has throughout time, arid, dusty and hoping one day for humans… of its own.


Timeline 7 ArrowClick on the image to play the animation.

 

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Sound compiled and edited by North High School, using a variety of sources in the public domain.