May 1, 2008 Astrophysicists used the Spitzer Space Telescope to scan a cluster of about 500 stars for evidence of a collision similar to the one that produced Earth's moon. The telescope searches in the infrared part of the spectrum, which allows researchers to search for the dust clouds created by massive collisions. The surface area of the dust would absorb light from the star and become warm. Researchers hypothesize that a maximum of five to ten percent of all moons form in the way that the Earth's did.
The moon is the brightest light in the night sky. We've sent space missions there, people have written countless songs and poems about it and now, astrophysicists are providing new insight on how the Earth's moon was created and what makes it special.
"Well, the moon is certainly the most dramatic thing in the sky, so I'm sure people have had ideas about where it came from the beginning," George Rieke, Ph.D., an astrophysicist at the University of Arizona in Tucson, Ariz., told Ivanhoe.
Dr. Rieke says our moon is unique -- formed by a massive collision in space. "There was another planet about the size of Mars that was on a disastrous orbit across the Earth's orbit and so the Earth and this other planet ran into each other," he says.
It happened 30 to 50 million years after the formation of the sun. "It was a huge collision that threw dust and debris out into space and some of that material somehow reassembled and orbited around the Earth and eventually built up a moon," Dr. Rieke explained.
Now, an infrared detector like this one on NASA's Spitzer Telescope is giving University of Arizona astrophysicists a wealth of new information from space. Researchers looked for evidence of dust debris around 430-million-year-old stars. Surprisingly, only one star was surrounded by dust, revealing that no other moon was formed like or since ours. "Nothing like that occurred around any of the other planets in our solar system," Dr. Rieke said.
Scientists believe our moon set the stage for life on earth as we know it. But it could have been very different. "It could have been, if the other planet was a little bit bigger that it would have just destroyed the Earth and there wouldn't be any Earth left," Dr. Rieke explained.
You may never look at the moon quite the same way again. "We should be a lot more thankful when we go out at night and find our way around through the full moonlight or just admire what it looks like," Dr. Rieke said. Astrophysicists believe that moons like the Earth's form in only five to ten percent of planetary systems in our universe.
THE FORMATION OF THE MOON: The Earth’s moon formed just 30 to 50 million years after the sun was formed, when an object the size of Mars collided with Earth, and released a giant cloud of dust along with the moon. After examining a cluster of about 500 stars with the Spitzer Space Telescope, the researchers found very little evidence of collisions. If there had been such an event, large amounts of dust would have remained in the solar system long after the creation of a moon. The telescope would have indirectly observed pieces of dust that had absorbed light from the star in their solar system and become warmer than the surroundings.
ABOUT THE SPITZER TELESCOPE: The Spitzer Space Telescope was launched on August 25, 2003. Spitzer detects the infrared energy radiated by objects in space. Most of this infrared radiation is blocked by the Earth's atmosphere and cannot be observed from the ground. Spitzer allows us to peer into regions of space that are hidden from optical telescopes. Many areas of space are filled with vast, dense clouds of gas and dust that block our view. Infrared light however can penetrate these clouds, allowing us to peer into regions of star formation, the centers of galaxies, and into newly forming planetary systems. Infrared also brings us information about the cooler objects in space, such as smaller stars which are too dim to be detected by their visible light, extrasolar planets, and giant molecular clouds.
The American Astronomical Society and the American Geophysical Union contributed to the information contained in the video portion of this report.