Our Moon: A look into the past, present and future

By Katy Nielsen

It controls the tides, regulates the seasons and has guided civilizations at night for thousands of years, yet few people know about this neighboring stellar object, how it formed and what will become of the moon. Its importance to the evolution of species and the development of earth might be fundamental to understanding humanity’s existence.

“The moon is very much part of our culture,” said Anthony F. Aveni, professor of astronomy and anthropology at Colgate University in Hamilton, NY. “It’s unfortunate we’ve lost contact with how much the moon is part of our daily lives and history. Now we just cast it aside.”

The first mission to the moon was the Soviet Union’s unmanned Luna 2 launched on Sept. 12, 1959 and landed on the moon Sept. 14. The U.S. responded with its Apollo 11 mission on July 20, 1969, which was the first manned mission to travel to the moon.

Since then, there have been six manned missions, but another mission with humans onboard is not planned for the near future because of high costs. However, scientists continue to study the moon. A recent discovery of metal in the moon’s water-filled craters is generating buzz among scientists and sparking renewed interest in it.

The moon’s future: spiraling away

Right now, the moon’s average distance from Earth is 384,403 kilometers, but that number increases every year. The moon is drifting away, and the Earth’s rotation is decreasing, which creates longer days.

“The moon’s getting farther away from us, about four centimeters a year,” said R. J. Rand professor in the Department of Physics and Astronomy at the University of New Mexico. “What’s impressive is we can measure the distance easily with radar. We bounce a radar signal from a telescope off the moon and measure how long the radar takes to come back.”

According to Douglas Hamilton, professor of Astronomy at University of Maryland, the earth and moon system will stabilize billions of years from now.

“At that time, the moon won’t appear to move in our sky the way it does now, and the tides won’t travel across the oceans the way they do now,” Rand said.

When that happens, one side of the Earth will face toward the moon, the same way one side of the moon faces the Earth now. This is called tidal locking, which has already happened to Pluto and its moon, Charon.

Tidal locking will happen billions of years from now, at which point the sun will play a significant role in what happens to the Earth next.

“The sun will slowly cause energy of the moon’s orbit to leak away, and the moon will come back and crash into the Earth,” Hamilton said. “But not to worry, by the time it happens the sun will already have exploded. The sun blows out into a red giant in five billion years.”

Lunar creation

Billions of years ago, an unknown planet the size of Mars collided with Earth, an event that lasted as long as 10 or 15 minutes. Scientists refer to the impact as a glancing blow, which means the object skimmed Earth without obliterating it.

The remaining particles—those not vaporized after the impact—coalesced because of Earth’s gravitational pull and created one large mass, our moon.

“It was a huge impact,” said Larry Ciupik, senior astronomer at Adler Planetarium, 1300 S. Lake Shore Drive. “If you don’t have a glancing blow, you don’t form anything but a single body. The Earth would have eventually absorbed the

whole thing.”

The planet that collided with Earth contained a large concentration of metal elements including gold and nickel, which led scientists to believe the collision caused an increase in Earth’s metal content.

Life without the moon

The moon functions as a season regulator, tide controller and overall stability enforcer for the planet, according to Ciupik. Without it, we may never have evolved into human beings, he said.

“The Earth’s weather would be very different because the moon keeps us kind of stable at about a 23 and a half degree tilt.

If the tilt varies a lot, over time, you get ice ages,” Ciupik said. “Vast climate changes would have occurred a lot more. That would have been a big problem for life.”

The Tides

The existence of the human species might be related to the constant movement of the oceans. Tides are created by friction between the Earth and the moon. Together, the objects pull on each other and cause the oceans to move.

“Our high tides all come from the gravity of the moon,” Hamilton said. “The sloshing of the oceans has interesting implications for life in tide pools and inter-tidal regions. It is possible life began in these environments.”

Leap Seconds

Every couple of years, the National Bureau of Standards adds one second to the world clock. These seconds are referred to as leap seconds. This is happening because the Earth’s orbit is gradually slowing down because of the friction between the Earth and moon.

Throughout history, the moon has functioned as a calendar for civilizations. It is a time keeper in ways similar to the sun.

“The moon is part of our calendar,” Ciupik said. “It also is affecting the length of the day. Eventually it will have more of an effect on us than it does now. We’re talking a long time, millions of years.”

The ancient Gauls had a calendar based on lunar months, aligned with a solar year, according to Michael Dietler, professor in the Department of Anthropology at University of Chicago.

“Archaeologists know the moon served as a temporal ordering marker,” Dietler said. The fact that the moon is altering the speed at which the Earth orbits will play a greater role in the distant future, but for now, leap seconds will continue to compensate for the shift.

Moon quakes

Like the Earth, the moon experiences quakes that shake its surface. Scientists refer to these as moon quakes, and they tend to occur when the moon gets close to the Earth on its

elliptical orbit.

“Unlike the Earth, the moon is a dead world that cooled off long ago, so there are no plate tectonics, there are no volcanoes,” Hamilton said. “There are only two things that lead to moon quakes: One is if something hits the moon, like a meteor, and the second is when the moon is distorted by the Earth’s gravity.”

When astronauts landed on the moon, they left seismometers to monitor surface activity.

“We’ve measured quite a few quakes, and we’ve actually used them to learn about the interior of the moon,” Rand said.

The seismic waves travel into the interior of the moon, teaching scientists about density changes in the moon’s core. That information relates to the moon’s composition and tells researches its past.

The vanishing eclipse

According to Ciupik, we live at a time when eclipses are visible to us, but millions of years ago they weren’t. Back then, the moon was much closer to the Earth, so the sun could not block it out. Eventually, the moon will be too small to block the sun out.

“Eclipses won’t be visible millions of years in the future,” Ciupik said. “So we live at a very special time.”

Right now, the moon and sun create an illusion in our sky. They appear to be the same size, and this allows the solar and lunar eclipses to take place.

Water on the moon

If water is separated into hydrogen and oxygen it can be used to breathe and drink. This is especially significant if humans build a lunar station.

“We thought it was totally dry for a long time,” Ciupik said. “But water can be used as rocket fuel. Think about hydrogen and oxygen separated and that’s rocket fuel.”

The moon has one-sixth the gravitational force as the Earth. Working in zero gravity is difficult for astronauts because they have no force to push against, Ciupik said.

In a Feb. 12 article published by NASA, titled “Waiter, there’s metal in my moon water,” author Bill Steigerwald presented a discovery that the moon’s water, located in its craters, contains magnesium, mercury, calcium and silver.

Scientists continue to learn more about the moon, and how, despite being a dead planet, it shares many of Earth’s characteristics.