by neufer » Thu Aug 21, 2008 6:01 pm
emc wrote:So are you telling me there's no hope of making bunny ears appear in our moon shadow?
Maybe if you can get Gort to help out...
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Artist Wants to Paint Moon, But Physics May Foil Plan
By Robert Roy Britt Senior Science Writer
posted: 07:00 am ET 10 August 2001
http://www.space.com/scienceastronomy/g ... 810-1.html
<<An artist hoping to recruit millions of laser-pointer owners to "paint the Moon" may instead be disappointed by physics.
James T. Downey, the artist behind the project, is intent on creating a "collaborative work of celestial art" by illuminating a fleeting red spot on our only natural satellite.
The event, an effort to help people "find the excitement of space," is scheduled for two nights, one in October and another in November. Downey has chosen a target location for the beams on the dark portion of the Moon while it's in its first-quarter. Each attempt would last five minutes. A web site, called "Paint the Moon," has been set up with instructions for where and how to point your laser and why you should participate.
"Inexpensive yet surprisingly powerful laser-pointing devices have become ubiquitous in America," said Downey. "Millions of people own such a device. Laser light stays coherent over vast distances, the beams spreading very little."
Lasers are powerful devices, concentrated bursts of energy that can damage the eye, cut through metal or, theoretically, shoot down enemy missiles. And all at the speed of light. Astronomers use lasers to measure distances between telescopes and even to enhance observations in order to improve resolution of light coming from distant stars. Experiments planted by Apollo astronauts allow scientists to use lasers to more accurately gauge the distance from Earth to the Moon, and even detect moonquakes.
But all technology has its limits. It seems there are not enough people in North America to make Downey's idea work.
"As I suspected, the number required is not millions of people, but more than millions of millions of millions of people," said Donald Umstadter, a laser expert at the Center for Ultrafast Optical Science at the University of Michigan, Ann Arbor.
Umstadter became curious about the project when SPACE.com asked him if it was feasible to illuminate the Moon in this way. He asked one of his graduate students, Chad Vandenbosch, to look into the possibility as a mathematical exercise.
To calculate how many people it would take to successfully make a temporary red spot on the Moon visible from Earth, Vandenbosch estimated several factors. He considered a typical handheld laser pointer's power and how much of the light would be absorbed by Earth's atmosphere, as well as how much of the laser light would be reflected by the Moon vs. how much would be absorbed.
As a premise, he based the calculations on what would be needed to make the spot visible to people in cities, where bright lights would obscure a faint spot that might otherwise be visible in rural locations.
A reader says there's another reason why this won't work.
Vandenbosch said there is a little wiggle room in his calculations due to the estimate of background light.
"The main thing to glean from the calculation is that the divergence of these pointers, due to their small aperture and a basic law of optics governing the diffraction of light, results in a huge diameter beam, and thus very dim beam, by the time it arrives at the Moon," Umstadter said.
Downey, the artist, was intrigued and a bit dismayed when he learned of Vandenbosch's science, but plans to proceed with the artistic attempt nonetheless.
"I knew that it would be a long shot from the start," Downey said. "But success is something that can be measured in a lot of ways. We may not be able to accomplish actually painting the Moon, but still the act of participating in something such as this has value."
In what way?
"If I can get people thinking about the Moon as something they might be able to touch, if I can get science teachers to talk about the physics involved, Moon phases, etc., if I can just help people find the excitement of space as part of the human drama again, then the project will have been a grand success."
Downey also doesn't want to spoil a good party.
"In emails, I hear from people who are planning parties around the event, who become enraptured with the whole notion and tell all their friends," he said. "Of course, I also hear from people who think the entire idea is just plain lunacy, and tell me I should be locked up for spreading such tripe. But hey, art is like that."
Downey came up with the idea as part of a novel he's writing, set 50 years into the future. "A couple of characters are discussing oddball things back at the beginning of the millenium, and this comes up. I thought that it would be fun if someone read my book (assuming I can get it published, of course) and actually tried to organize such an event, thereby having life imitate art.">>
[quote="emc"]So are you telling me there's no hope of making bunny ears appear in our moon shadow? :([/quote]
Maybe if you can get Gort to help out...
----------------------------------------------
Artist Wants to Paint Moon, But Physics May Foil Plan
By Robert Roy Britt Senior Science Writer
posted: 07:00 am ET 10 August 2001
http://www.space.com/scienceastronomy/generalscience/laser_moon_010810-1.html
<<An artist hoping to recruit millions of laser-pointer owners to "paint the Moon" may instead be disappointed by physics.
James T. Downey, the artist behind the project, is intent on creating a "collaborative work of celestial art" by illuminating a fleeting red spot on our only natural satellite.
The event, an effort to help people "find the excitement of space," is scheduled for two nights, one in October and another in November. Downey has chosen a target location for the beams on the dark portion of the Moon while it's in its first-quarter. Each attempt would last five minutes. A web site, called "Paint the Moon," has been set up with instructions for where and how to point your laser and why you should participate.
"Inexpensive yet surprisingly powerful laser-pointing devices have become ubiquitous in America," said Downey. "Millions of people own such a device. Laser light stays coherent over vast distances, the beams spreading very little."
Lasers are powerful devices, concentrated bursts of energy that can damage the eye, cut through metal or, theoretically, shoot down enemy missiles. And all at the speed of light. Astronomers use lasers to measure distances between telescopes and even to enhance observations in order to improve resolution of light coming from distant stars. Experiments planted by Apollo astronauts allow scientists to use lasers to more accurately gauge the distance from Earth to the Moon, and even detect moonquakes.
But all technology has its limits. It seems there are not enough people in North America to make Downey's idea work.
"As I suspected, the number required is not millions of people, but more than millions of millions of millions of people," said Donald Umstadter, a laser expert at the Center for Ultrafast Optical Science at the University of Michigan, Ann Arbor.
Umstadter became curious about the project when SPACE.com asked him if it was feasible to illuminate the Moon in this way. He asked one of his graduate students, Chad Vandenbosch, to look into the possibility as a mathematical exercise.
To calculate how many people it would take to successfully make a temporary red spot on the Moon visible from Earth, Vandenbosch estimated several factors. He considered a typical handheld laser pointer's power and how much of the light would be absorbed by Earth's atmosphere, as well as how much of the laser light would be reflected by the Moon vs. how much would be absorbed.
As a premise, he based the calculations on what would be needed to make the spot visible to people in cities, where bright lights would obscure a faint spot that might otherwise be visible in rural locations.
A reader says there's another reason why this won't work.
Vandenbosch said there is a little wiggle room in his calculations due to the estimate of background light.
"The main thing to glean from the calculation is that the divergence of these pointers, due to their small aperture and a basic law of optics governing the diffraction of light, results in a huge diameter beam, and thus very dim beam, by the time it arrives at the Moon," Umstadter said.
Downey, the artist, was intrigued and a bit dismayed when he learned of Vandenbosch's science, but plans to proceed with the artistic attempt nonetheless.
"I knew that it would be a long shot from the start," Downey said. "But success is something that can be measured in a lot of ways. We may not be able to accomplish actually painting the Moon, but still the act of participating in something such as this has value."
In what way?
"If I can get people thinking about the Moon as something they might be able to touch, if I can get science teachers to talk about the physics involved, Moon phases, etc., if I can just help people find the excitement of space as part of the human drama again, then the project will have been a grand success."
Downey also doesn't want to spoil a good party.
"In emails, I hear from people who are planning parties around the event, who become enraptured with the whole notion and tell all their friends," he said. "Of course, I also hear from people who think the entire idea is just plain lunacy, and tell me I should be locked up for spreading such tripe. But hey, art is like that."
Downey came up with the idea as part of a novel he's writing, set 50 years into the future. "A couple of characters are discussing oddball things back at the beginning of the millenium, and this comes up. I thought that it would be fun if someone read my book (assuming I can get it published, of course) and actually tried to organize such an event, thereby having life imitate art.">>