The theory of two moons

"Blue Moon, you saw me standing alone. Without a dream in my heart, without a love of my own …" is the first line or two of a traditional ballad written by Rodgers and Hart in 1935. But a recent paper presented by astronomers proposes that maybe our moon was not alone in the night sky. Astronomers Erik Asphaug and Martin Juzi presented the idea that perhaps the moon was joined by a smaller moon in orbiting the Earth over four and a half billion years ago, but that the two moons eventually collided.

The scientists have proposed this theory in an effort to explain why the dark side of the moon has a landscape that is quite different from the visible side of the satellite. From imagery taken by lunar orbiters and telescopes as well as our moon missions, scientists know the dark side of the moon which we never see is quite hilly in contrast with the relatively smoother side of the moon that faces us. In addition our lunar satellite appears somewhat lopsided.

Asphaug and Juzi explained in their paper the reason for this was a collision between our present moon and its lightweight partner that orbited our planet over 4 billion years ago. According to the scientists, the difference in masses between the two theoretical moons caused the lighter moon to collide with our present moon.

Asphaug said this collision was a relatively slow motion crash albeit at 5000 miles per hour. To observers on Earth, one would have seen the lighter moon dissolve into our larger moon and as it did it created debris and rocks that would have spread across the surface of our moon. "There would be no crater because there was not sufficient speed to create one."

He compared it to watching a bullet take ten minutes to bury itself into a rock. "People would be bored looking at it because it's taking 10 minutes just for the bullet to bury itself in the moon http://www.foxnews.com/scitech/2011/08/03/earth-once-had-second-moon-astronomers-say/? intcmp=obinsite. This is an event if you were looking at, you'd need a big bag of popcorn." At the end of the day, the moon's surface would be completely different between the near and far sides of it.

We only live for a relatively short time period on this planet we call Earth and a story like this makes one wonder what life was like in the infancy of our solar system. Those who study our history and cosmology describe quite a violent beginning with planets, asteroids and comets colliding with each other in a cosmic game of demolition derby. Very few life forms probably would have survived such a turbulent age.

One current theory is this most recent story of the moon is typical of how our planets formed. One theory about the origin of our solar system is it started out as dense dust and rock surrounding the sun and as the dust cooled and slowed it began to solidify into masses and these millions of masses began colliding at high speeds gradually cleaning the orbits of the sun of all the debris and creating the planets we now know today.

While this is a simplistic description, it is one of the basic theories of how the solar system originated.

It must have been a grand time to observe this creation process and seeing it may answer many more questions. Water would have come from ice rocks and comets colliding with the planets and evaporating to create atmospheres.

The moon has been our cosmic neighbor for the entire history of humanity. It has awed, inspired, scared and pleased millions and millions of people through the years. We cannot imagine our world without a moon.

The world probably would be different without this celestial neighbor. Imagine the oceans without the tides. Imagine the night without that full moon. In essence the sky would continually be a new moon sky. Many songs that use the moon would not exist such as "Blue Moon", "Moonbeam", "Moon River", "Fly Me to the Moon" and even Ozzy Osborne's "Bark at the Moon".

Cultures that used the lunar calendar like the native Americans would have had problems as well. The lunar month which lasts about 29.5 days which is almost twelve and a half cycles in our current year.

I'm not sure if most people are aware of it, but we only see one side of the moon. As it turns out not only does the moon orbit the Earth but it spins in conjunction with us so that we only see the same side of the moon all the time. This of course has led to theories that something may be hidden on the dark side of the moon such as lunar bases or extraterrestrial outposts although this is probably more flights of fancy than fact.

It was a proud period of American history when we landed on the moon and our astronauts explored the lunar surface on television in 1969. This also led to one of the largest conspiracy theories of our time in that some proposed the landing was faked on a soundstage. This fantasy was the inspiration about a conspiracy to fake a mission to Mars in the 1978 film "Capricorn One."

So even though the moon is thousands of miles away, it still awes us, inspires us and thrills us even today as it spends its days circling our world. In many ways, the world would not be the same without it.

Til next time …