Recent volcanoes that rocked the lunar surface prove the moon was not as dormant as previously thought. The Lunar Reconnaissance Orbiter has cleared up the mystery of IMP’s, or irregular mare patches, found on the moon. Earth’s companion was hot much longer than astronomers believed.
When people gaze at the moon they usually see the man in the moon looking back down at them. In the United States people see a face, but in Europe they envision an entire man. In East Asia people see a rabbit; in India, a pair of hands; in Hawaii a tree and in New Zealand a woman. The human brain tries to make sense out of chaos and searches for meaning in random patterns. This natural phenomenon is called pareidolia. So humans, who have spent millennia contemplating the orb, see pictures amidst the dark and light patches of the moon’s surface. This pattern of patches never changes.
There are two basic reasons for the unchanging face of the moon. First, because the moon rotates and revolves at the same rate, the same side always points towards Earth. Earth’s view of the moon never varies. There really is a dark side of the moon. At times, the far side of the moon faces the sun, but it never faces the earth. It remained a mystery until Christmas Eve 1968 when the astronauts on America’s Apollo 8 became the first people to view the dark side and send images back to the rest of humanity. The pioneer flight around the moon increased curiosity about the man’s nearest extraterrestrial neighbor.
The second reason the moon always looks the same is because the surface has not changed for over a billion years, or so scientists thought. The moon and the earth formed concurrently approximately four and a half billion years ago. Both were extremely volcanically active in their early stages. Whereas the earth has retained a liquid outer core and a plastic layer between the crust and mantle, it was thought the much smaller moon had completely cooled between one and one and a half billion years ago. During its volcanic period, the surface became covered with light-colored anorthosite made mostly of plagioclase feldspar. Later, massive eruptions caused dark-colored basalt to spill across the plains. The lunar maria formed, covering 17 percent of the moon. Basalt is dark because it contains the iron-rich minerals pyroxene, olivine and ilmenite. Fortunately for humans, the multi-colored side of the moon faces earth. The far side of the moon is almost entirely light-colored but with dramatic impact craters from meteorites. There is no atmosphere or water on the moon to cause weathering or erosion. There is no rock cycle to form sedimentary or metamorphic rocks. So the lunar landscape remains fixed.
For over three billion years magma roiled under the lunar crust, formed volcanoes, and erupted to create the colors and contours of the moon. Now the moon is a chunk of cold rock. New evidence has emerged that volcanoes have erupted fairly recently on the moon. NASA’s Lunar Reconnaissance Orbiter has identified numerous areas that may have experienced volcanic eruption as recently as 33 million years ago. In 1971 the crew of Apollo 15 took pictures of a strange patch of rock that was eventually named Ina. Over the years, 70 more “irregular mare patches,” or IMP’s have been discovered. With the close examination provided by the Lunar Reconnaissance Orbiter, astronomers have come to the conclusion that the IMP’s are remnants of recent volcanic activity. It may not seem that 33 million years ago is recent, but in a geologic time scale of five billion years, it is just yesterday. The dinosaurs were already dead, mammals were wandering the earth, and grasses beginning to grow.
The moon was not dormant for billions of years, but may have experienced volcanic activity as recently as 33 million years ago. Closer examination of the moon is revealing more of its mysteries. The moon and the earth have interacted for 4.5 billion years. The earth caused a bulge in the moon which slowed the moon’s orbit. In turn, as water covered the earth the moon affected the tides. The friction of the tides slowed the rotation of the earth from a few hours to the current 24. Because of the duality of its proximity and great distance, humans remain fascinated with the moon. The more they learn, the more there is to know.
By: Rebecca Savastio