If you've heard the story of the birth of Jesus of Nazareth you've almost certainly heard of the star which guided the three wise men to Jesus. Here is a great link about The Christmas Star.
Let me answer a question that you may have for me, "do you believe that story?"
The more I study, the deeper I get an understanding of the nearly infinitely larger macrocosmos and the seemingly equally infinite microcosmos the more I believe in God. Not just "a" god but the God written about in the Bible used by Christians and the older writings used in the Jewish religion. Oh, I believe that a lot of the stories in there are inadequate expressions of older generations who failed to completely understand, as we do, the fullness of their experience.
In every way that I examine our existence I see less likelihood that we "just happened". Intelligent design is the buzzword today for creation. I think more than anything my thoughts are affirmed in science which gives me faith. If you study quantum physics and master the understanding of the increasingly small and if you study the heavens and explore the increasingly large I believe it is impossible to not question how it all happened which ultimately leads to the question of why it all happened.
Sunday, December 25, 2005
Tuesday, December 20, 2005
Cloudy Night Astronomy
So it's rainy, snowy, stormy, or just plain yucky outside but you're itching to get a glimpse of your favorite space object. What to do? You're in luck! Some guy invented the internet just for you.
You could do a little digging and find these resources on your own but since I've already done some of the work I thought it would speed up your enjoyment to share. Some of these sites have images that are very large and if you're on dial up they'll take a long time to download. Fortunately the developers of many of the sites used low res (low resolution small file size images) so you can enjoy a smaller version of the same photo.
I've tried to include only sites that give indepth information about the images you'll find or sites that provide good search engines. Otherwise how will you learn anything new?
http://www.seds.org/images/ is from Students for the Exploration and Development of Space (SEDS) hosted by The University of Arizona. It includes a searchable and browsable database of a lot of images and all good quality with too short information - but the search engine makes up for some lack of info. The main site does provide a great amount of indepth information, too.
http://www.kopernik.org/spaceimages/index.asp The Kopernik Polish Cultural Society of Broome County was founded in 1973 to help commemorate the 500th anniversary of the birth of Mikolaj Kopernik, a man known to the world as Copernicus - "the father of modern astronomy". The Kopernik Society undertook construction of the Kopernik Observatory in the fall of 1973. When the Observatory was opened to the public in June of 1974, the Kopernik Society donated the facility to the community to be operated by Roberson Museum and Science Center. Since that time hundreds of thousands of school children and families have seen the wonders of the universe through the Observatory's large telescopes.
http://hubblesite.org/gallery/ probably doesn't need much explanation. Some of the greatest deep space images of all time. The Hubble space telescope will soon be decomissioned but we have the images and you can access them any time from the dryness and comfort of your own home.
http://science.hq.nasa.gov/multimedia/index.html who could do space images and information better than NASA? You guessed it: nobody. Here is one of the most information packed collection of space images I've found. Enjoy!
http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery.html the NSSDC photo library provided by NASA and FirstGov is very cool, too. It also provides, being a part of NASA, the same quality of images and information.
http://www.space.gc.ca/asc/app/gallery/search.asp great images from the Canadian Space Agency. Good information with each photo but a litte hard to use unless you know what you're looking for. The search engine is good but you'll need to know what to search for. Try typing in nebula or mars.
http://www.spacetoday.org/Weblinks/spacepix.html Space Today Online is very easy to read and provides very good basic language information. If you like Beginning Astronomy - Sky Watchers you'll love STO, too! "STO is a definitive news, information and education site on the World Wide Web dedicated to space science, astronomy and related subjects. By communicating the record of human activities in and about space, Space Today Online delivers on its commitment to a greater public understanding of and enthusiasm for human space research and travel."
You could do a little digging and find these resources on your own but since I've already done some of the work I thought it would speed up your enjoyment to share. Some of these sites have images that are very large and if you're on dial up they'll take a long time to download. Fortunately the developers of many of the sites used low res (low resolution small file size images) so you can enjoy a smaller version of the same photo.
I've tried to include only sites that give indepth information about the images you'll find or sites that provide good search engines. Otherwise how will you learn anything new?
http://www.seds.org/images/ is from Students for the Exploration and Development of Space (SEDS) hosted by The University of Arizona. It includes a searchable and browsable database of a lot of images and all good quality with too short information - but the search engine makes up for some lack of info. The main site does provide a great amount of indepth information, too.
http://www.kopernik.org/spaceimages/index.asp The Kopernik Polish Cultural Society of Broome County was founded in 1973 to help commemorate the 500th anniversary of the birth of Mikolaj Kopernik, a man known to the world as Copernicus - "the father of modern astronomy". The Kopernik Society undertook construction of the Kopernik Observatory in the fall of 1973. When the Observatory was opened to the public in June of 1974, the Kopernik Society donated the facility to the community to be operated by Roberson Museum and Science Center. Since that time hundreds of thousands of school children and families have seen the wonders of the universe through the Observatory's large telescopes.
http://hubblesite.org/gallery/ probably doesn't need much explanation. Some of the greatest deep space images of all time. The Hubble space telescope will soon be decomissioned but we have the images and you can access them any time from the dryness and comfort of your own home.
http://science.hq.nasa.gov/multimedia/index.html who could do space images and information better than NASA? You guessed it: nobody. Here is one of the most information packed collection of space images I've found. Enjoy!
http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery.html the NSSDC photo library provided by NASA and FirstGov is very cool, too. It also provides, being a part of NASA, the same quality of images and information.
http://www.space.gc.ca/asc/app/gallery/search.asp great images from the Canadian Space Agency. Good information with each photo but a litte hard to use unless you know what you're looking for. The search engine is good but you'll need to know what to search for. Try typing in nebula or mars.
http://www.spacetoday.org/Weblinks/spacepix.html Space Today Online is very easy to read and provides very good basic language information. If you like Beginning Astronomy - Sky Watchers you'll love STO, too! "STO is a definitive news, information and education site on the World Wide Web dedicated to space science, astronomy and related subjects. By communicating the record of human activities in and about space, Space Today Online delivers on its commitment to a greater public understanding of and enthusiasm for human space research and travel."
Saturday, December 17, 2005
Watching Satellites
Did you know that you can see satellites with just your eyes? Incredible as it may seem this is one of the things that really got me interested in looking skyward. I was 20 years old when I realized that I saw my first satellite. After that I looked for them frequently. They look, to me, just like stars only they are moving ... some very quickly.
The next memorable experience of satellite watching was when my son was about 12. I told him we could see satellites just like on "Rocket Boys" and that got him excited. Within about 20 minutes he saw his first satellite flying over. Unlike me he's still not very interested in star watching or space exploration.
Do you want to see a satellite? It's really quite simple. I've noticed that the best time to view is either about 30 minutes after the sun sets or about 30 minutes before the sun rises. Obviously you need to have clear skies because satellites circle the earth high above the clouds. Most are orbiting at about 500 miles above the surface of the planet.
There are several internet sites that have information about spotting satellites. Here are some including my favorite one other than Starry Night software.
J-Track Satellite Tracking from NASAis my favorite free to use tacking software. It's pretty simple to use and gives you the exact time to walk out and look up. As long as you know where you live (go to this link and type in your address) you can be sitting inside playing a video game or reading about space exploration and walk out just in time to look up and see the satellite pass over.
Heavens Above is a site that I've used often but it provides great information about satellites and their locations. This site is more text based and a little harder to use than J-Track (above) but they have recently added more active graphics.
Most satellites are smaller than your family car. Some, such as the International Space Station or the one of the NASA Space Shuttles are much larger. Some satellites are orbiting in what is called a Geostationary Operational Environmental Satellite(GOES) which means it appears to you, if you are standing on the ground looking up, to be stationary. They orbit the earth high above and at a speed matching the rotation speed of the planet. They are also harder to see because they orbit the earth at about 22,000 miles high. The Shuttles orbit at about 140 miles and is very easy to spot when in orbit.
Polar Orbiting Earth Satellites (POES) go around the earth at about 1000 miles and move very quickly, about 1000 miles per hour. With any satellite the orbiting speed depends on the height of the orbit. The higher the orbit the slower it can move in relation to the surface.
The earth rotates from east to west at 1041 miles per hour. If you want to match the speed of the rotation of the earth and you are high above it you need to do some math to determine your "space speed". Physics are required and an understanding of centripetal force is key to determining the correct speed of orbit. That's a little too advance for this article but if you want a sneak preview just look at this link.
To end this article I recommend you plan on spending some time laying on your back or in a reclining chair on a clear night just after sunset and looking for "stars" that are moving. You'll know when you find a satellite. They don't flash, the don't change speed or direction and they move a little faster than most jetliners. Let me know what you see, we're all interested!
The next memorable experience of satellite watching was when my son was about 12. I told him we could see satellites just like on "Rocket Boys" and that got him excited. Within about 20 minutes he saw his first satellite flying over. Unlike me he's still not very interested in star watching or space exploration.
Do you want to see a satellite? It's really quite simple. I've noticed that the best time to view is either about 30 minutes after the sun sets or about 30 minutes before the sun rises. Obviously you need to have clear skies because satellites circle the earth high above the clouds. Most are orbiting at about 500 miles above the surface of the planet.
There are several internet sites that have information about spotting satellites. Here are some including my favorite one other than Starry Night software.
J-Track Satellite Tracking from NASAis my favorite free to use tacking software. It's pretty simple to use and gives you the exact time to walk out and look up. As long as you know where you live (go to this link and type in your address) you can be sitting inside playing a video game or reading about space exploration and walk out just in time to look up and see the satellite pass over.
Heavens Above is a site that I've used often but it provides great information about satellites and their locations. This site is more text based and a little harder to use than J-Track (above) but they have recently added more active graphics.
Most satellites are smaller than your family car. Some, such as the International Space Station or the one of the NASA Space Shuttles are much larger. Some satellites are orbiting in what is called a Geostationary Operational Environmental Satellite(GOES) which means it appears to you, if you are standing on the ground looking up, to be stationary. They orbit the earth high above and at a speed matching the rotation speed of the planet. They are also harder to see because they orbit the earth at about 22,000 miles high. The Shuttles orbit at about 140 miles and is very easy to spot when in orbit.
Polar Orbiting Earth Satellites (POES) go around the earth at about 1000 miles and move very quickly, about 1000 miles per hour. With any satellite the orbiting speed depends on the height of the orbit. The higher the orbit the slower it can move in relation to the surface.
The earth rotates from east to west at 1041 miles per hour. If you want to match the speed of the rotation of the earth and you are high above it you need to do some math to determine your "space speed". Physics are required and an understanding of centripetal force is key to determining the correct speed of orbit. That's a little too advance for this article but if you want a sneak preview just look at this link.
To end this article I recommend you plan on spending some time laying on your back or in a reclining chair on a clear night just after sunset and looking for "stars" that are moving. You'll know when you find a satellite. They don't flash, the don't change speed or direction and they move a little faster than most jetliners. Let me know what you see, we're all interested!
Tuesday, December 06, 2005
List of Astronomy Clubs
Getting started in astronomy can find some easy and fun help. Learning from the experiences and experience of others is a great way to get rolling. Here is a list of several Astronomy Clubs throughout the world (mostly in the United States):
Saguaro Astronomy Club
The Saguaro Astronomy Club (SAC) was formed in 1977 to promote fellowship and the exchange of information among its members -- amateur astronomers. SAC members meet monthly for both general meetings and observing sessions, and regularly conducts and supports public programs on astronomy.
The Northern Virginia Astronomy Club (NOVAC)
NOVAC is located in the state of Virginia, in the United States of America. Our members primarily reside in the counties near Washington D.C. Our primary purpose is providing enjoyment and education to the public (and ourselves!) through amateur astronomy. We strive to be a friendly club with a focus on observing, and we are one of the largest clubs in the United States with almost 1000 members.
Rockland Astronomy Club
Founded in 1958, Rockland Astronomy is one of the East Coast's premier astronomy club
and astronomy education organization. Providing an exciting array of activities
not available elsewhere. Rockland Astronomy will be your portal to the
wonders of the universe through our outstanding lectures, workshops, star parties,
planetarium shows, films, and much,much more.
The Society for Telescope, Astronomy and Radio
S*T*A*R is a registered non-profit educational amateur astronomy society located in Monmouth County, New Jersey. Membership is open to anyone interested in any area of astronomy.
The Raleigh Astronomy Club
The Raleigh Astronomy Club is a non-profit organization dedicated to educating and promoting amateur astronomy and is a member of the Astronomical League.
The Atlanta Astronomy Club
The AAC was founded in 1947 By Dr. William Calder, Chair of Astronomy at Agnes Scott College, to promote amateur astronomy and professional and amateur collaboration. It is one of the oldest and, with over 380 members, one of the largest clubs in the southeastern United States.
North Houston Astronomy Club
NHAC is a non-profit organization sponsored by Kingwood College, North Harris Montgomery Community College District. NHAC is dedicated to increasing the awareness and knowledge of the science of Astronomy.
The Huachuca Astronomy Club
The Huachuca Astronomy Club (or HAC) is Cochise County, Arizona's premier astronomy club. The pronunciation of the Native American word 'Huachuca', as best as I can do, is Waa-chew-Ka. The closest translation to English is 'Thunder Mountain'. With 'home base' at Cochise College in the heart of Sierra Vista, the Huachuca Astronomy Club also serves the communities of Hereford, Palominas, Fort Huachuca, Bisbee, historic Tombstone, Douglas, Huachuca City, Benson, Willcox, Sonoita (in Santa Cruz County), and other surrounding areas. Even Tucson is represented, by some who prefer the Huachuca Astronomy Club's smaller-town, friendlier atmosphere. (Tucson is approximately 60 miles NW from Sierra Vista.)
The Prairie Astronomy Club
The Prairie Astronomy Club was founded in 1961 as a non-profit organization dedicated to encouraging the study of Astronomy and related subjects for the benefit of its members and the general public. The club presently has over 80 members with a wide variety of interests ranging from simple naked-eye sky gazing to deep-sky objects, variable star observing, and the use of computers. The club holds monthly meetings open to the general public on THE LAST TUESDAY OF EACH MONTH, unless the date conflicts with a major holiday. The meetings are held at 7:30 p.m. at the HYDE MEMORIAL OBSERVATORY located in HOLMES PARK in southeast LINCOLN, NEBRASKA.
Alachua Astronomy Club, Inc.
The AAC was founded September 1987 when Dr. Armen C. Tarjan (Charlie) contacted astronomy professor Howard L. Cohen and asked if Gainesville had an astronomy club. Professor Cohen responded, "Not any longer,* but do you want to start one!" The AAC flourished over the next eleven years and was incorporated as a not for profit organization under the laws of the State of Florida on the fifteenth day of the month of January 1999 at 17:08 Universal Time.
Santa Cruz Astronomy Club
The Santa Cruz Astronomy Club serves all communities in Santa Cruz County, California as well as many members from neighboring areas via our Newsletter the Observer. The emphasis of our club is Observational Astronomy, family participation and public enjoyment of the wonders of the starry night.
East Valley Astronomy Club
East Valley Astronomy Club (EVAC) is a group of more than 200 astronomy enthusiasts in the eastern part of Valley of the Sun. We started out in 1987 as a small band of amateur astronomers in the eastern suburbs of Phoenix, hence the name "East Valley Astronomy Club." We incorporated as a non-profit organization in 1996. Our membership now includes people from all over the valley, even a few from out of town. Our purpose is simple: to forge a network of friendly people with a common interest in star-gazing and astronomical science. We also promote public awareness and education of astronomy by sponsoring viewing sessions for both the general public and local area schools.
North Shore Amateur Astronomy Club
Two of the principal goals of the NSAAC are to promote a wider appreciation of astronomy and to help people choose the most appropriate telescope or binocular for their interest and budget. You do not need a telescope for stargazing, and you do not have need one to become a member of the NSAAC ! In fact, we recommend that you join us for a few observing sessions and look through the many varieties of telescopes owned by our members before making a purchase.
New Mexico Tech Astronomy Club
New Mexico Tech Astronomy Club is a student supported and run club that focuses primarily on public outreach. Outreach is available to anyone for free. The club runs the Etscorn Observatory at New Mexico Tech where most of our public outreach is conducted. Members can also use the facilities almost anytime. Club members are mostly Tech students but we also have members from all over New Mexico who participate in varying degrees. Occasionally the club goes on field trips and sometimes get special VIP tours at such places as the VLA and Chaco Canyon.
Castle Point Astronomy Club
The club is proud to possess various astronomical telescopes that are available to the members for loan, in order that they may have the opportunity to survey the skies at their leisure. This both enables those unable to afford their own telescope the opportunity to enjoy observation, and also enables those thinking of purchasing a telescope to get the feel of using one!
Amhurst Astronomy Organization
Founded 1993, AA is a Public-Service, Non-Profit Organization Supporting : Astronomy, Education, Members, Science, & The Public. AA Conducts 100+ Scheduled Programs & 600+ Individual Member Programs.
Saguaro Astronomy Club
The Saguaro Astronomy Club (SAC) was formed in 1977 to promote fellowship and the exchange of information among its members -- amateur astronomers. SAC members meet monthly for both general meetings and observing sessions, and regularly conducts and supports public programs on astronomy.
The Northern Virginia Astronomy Club (NOVAC)
NOVAC is located in the state of Virginia, in the United States of America. Our members primarily reside in the counties near Washington D.C. Our primary purpose is providing enjoyment and education to the public (and ourselves!) through amateur astronomy. We strive to be a friendly club with a focus on observing, and we are one of the largest clubs in the United States with almost 1000 members.
Rockland Astronomy Club
Founded in 1958, Rockland Astronomy is one of the East Coast's premier astronomy club
and astronomy education organization. Providing an exciting array of activities
not available elsewhere. Rockland Astronomy will be your portal to the
wonders of the universe through our outstanding lectures, workshops, star parties,
planetarium shows, films, and much,much more.
The Society for Telescope, Astronomy and Radio
S*T*A*R is a registered non-profit educational amateur astronomy society located in Monmouth County, New Jersey. Membership is open to anyone interested in any area of astronomy.
The Raleigh Astronomy Club
The Raleigh Astronomy Club is a non-profit organization dedicated to educating and promoting amateur astronomy and is a member of the Astronomical League.
The Atlanta Astronomy Club
The AAC was founded in 1947 By Dr. William Calder, Chair of Astronomy at Agnes Scott College, to promote amateur astronomy and professional and amateur collaboration. It is one of the oldest and, with over 380 members, one of the largest clubs in the southeastern United States.
North Houston Astronomy Club
NHAC is a non-profit organization sponsored by Kingwood College, North Harris Montgomery Community College District. NHAC is dedicated to increasing the awareness and knowledge of the science of Astronomy.
The Huachuca Astronomy Club
The Huachuca Astronomy Club (or HAC) is Cochise County, Arizona's premier astronomy club. The pronunciation of the Native American word 'Huachuca', as best as I can do, is Waa-chew-Ka. The closest translation to English is 'Thunder Mountain'. With 'home base' at Cochise College in the heart of Sierra Vista, the Huachuca Astronomy Club also serves the communities of Hereford, Palominas, Fort Huachuca, Bisbee, historic Tombstone, Douglas, Huachuca City, Benson, Willcox, Sonoita (in Santa Cruz County), and other surrounding areas. Even Tucson is represented, by some who prefer the Huachuca Astronomy Club's smaller-town, friendlier atmosphere. (Tucson is approximately 60 miles NW from Sierra Vista.)
The Prairie Astronomy Club
The Prairie Astronomy Club was founded in 1961 as a non-profit organization dedicated to encouraging the study of Astronomy and related subjects for the benefit of its members and the general public. The club presently has over 80 members with a wide variety of interests ranging from simple naked-eye sky gazing to deep-sky objects, variable star observing, and the use of computers. The club holds monthly meetings open to the general public on THE LAST TUESDAY OF EACH MONTH, unless the date conflicts with a major holiday. The meetings are held at 7:30 p.m. at the HYDE MEMORIAL OBSERVATORY located in HOLMES PARK in southeast LINCOLN, NEBRASKA.
Alachua Astronomy Club, Inc.
The AAC was founded September 1987 when Dr. Armen C. Tarjan (Charlie) contacted astronomy professor Howard L. Cohen and asked if Gainesville had an astronomy club. Professor Cohen responded, "Not any longer,* but do you want to start one!" The AAC flourished over the next eleven years and was incorporated as a not for profit organization under the laws of the State of Florida on the fifteenth day of the month of January 1999 at 17:08 Universal Time.
Santa Cruz Astronomy Club
The Santa Cruz Astronomy Club serves all communities in Santa Cruz County, California as well as many members from neighboring areas via our Newsletter the Observer. The emphasis of our club is Observational Astronomy, family participation and public enjoyment of the wonders of the starry night.
East Valley Astronomy Club
East Valley Astronomy Club (EVAC) is a group of more than 200 astronomy enthusiasts in the eastern part of Valley of the Sun. We started out in 1987 as a small band of amateur astronomers in the eastern suburbs of Phoenix, hence the name "East Valley Astronomy Club." We incorporated as a non-profit organization in 1996. Our membership now includes people from all over the valley, even a few from out of town. Our purpose is simple: to forge a network of friendly people with a common interest in star-gazing and astronomical science. We also promote public awareness and education of astronomy by sponsoring viewing sessions for both the general public and local area schools.
North Shore Amateur Astronomy Club
Two of the principal goals of the NSAAC are to promote a wider appreciation of astronomy and to help people choose the most appropriate telescope or binocular for their interest and budget. You do not need a telescope for stargazing, and you do not have need one to become a member of the NSAAC ! In fact, we recommend that you join us for a few observing sessions and look through the many varieties of telescopes owned by our members before making a purchase.
New Mexico Tech Astronomy Club
New Mexico Tech Astronomy Club is a student supported and run club that focuses primarily on public outreach. Outreach is available to anyone for free. The club runs the Etscorn Observatory at New Mexico Tech where most of our public outreach is conducted. Members can also use the facilities almost anytime. Club members are mostly Tech students but we also have members from all over New Mexico who participate in varying degrees. Occasionally the club goes on field trips and sometimes get special VIP tours at such places as the VLA and Chaco Canyon.
Castle Point Astronomy Club
The club is proud to possess various astronomical telescopes that are available to the members for loan, in order that they may have the opportunity to survey the skies at their leisure. This both enables those unable to afford their own telescope the opportunity to enjoy observation, and also enables those thinking of purchasing a telescope to get the feel of using one!
Amhurst Astronomy Organization
Founded 1993, AA is a Public-Service, Non-Profit Organization Supporting : Astronomy, Education, Members, Science, & The Public. AA Conducts 100+ Scheduled Programs & 600+ Individual Member Programs.
Sunday, December 04, 2005
How Do We Measure the Speed of Light?
You may have learned that the speed of light is 186,282 miles per second. (299,792,458 meters per second.) You may also know that Alpha Centauri is in the nearest stellar system which is also a part of our galaxy and it is about 4.35 light years away. But how do we know this?
Before it was proven by Thomas Young that light traveled in waves just like sound it was believed that light was composed of particles (Newton's idea) which traveled through the "ether". Now we know there is no ether as it was presented and light travels in waves. Recently scientists were able to greatly slow the speed of light by transmitting it through an optically dense substance called Bose-Einstein Condensate. The Condensate is made up of atoms of rubidium cooled to almost absolute zero. There is a lot more information about bosons and condensates but most of them are far above the basics of physics needed to be known to understand how to measure the speed of light.
Albert Einstein's Theory of Relativity uses "c" to represent the constancy of the speed of light. It is now believed that light itself may be able to travel faster than the speed of light at least within light (not important for this discussion) and through experiments we have been able to slow down and even stop (freeze) light. But for all current and practical knowledge we believe that the speed of light through a non-vacuum is 3 x 10(8th) meters per second.
Galileo may have been the first scientist to try and measure the speed of light and he used a very rudimentary set of tools: two lanterns. He and an assistant separated themselves by about a mile Galileo would uncover his lamp allowing light to shine and as soon as his assistant saw the light from Galileo's lamp he would uncover his. Galileo judged this to be instantaneous. Well, he was almost right. It takes about 1700 billionths of a second for light to travel one mile.
Ole Roemer used the moons of Jupiter to prove that the speed of light could be measured (that it was not infinite). He noticed that when the orbits of Jupiter and Earth were closer he could see the moons of Jupiter much earlier than when Earth and Jupiter were at their farthest distance. In fact that amount of time turned out to be 16 minutes and 40 seconds though Roemer evidently held it to be 22 minutes and a few seconds. While Roemer did calculate the speed of light from these numbers he was actually of by 50%. Roemer calculated the speed of light to be 1.5 x 10(8th) meters per second - 1/2 slower than actual. The formula he used was to calculate the time it took for the light of Io to reach the surface of the earth in both the perigee and apogee of the orbits of Earth and Jupiter. Knowing the orbit of Earth to be 2 astronomical units he simply divided that time by the distance. He was wrong but he was on the right track. The year was 1675.
In 1849 we finally had the first non-space related measurement of the speed of light by a French physicist named Armand Hippolyte Louis Fizeau. Fizeau used a wheel with "teeth" cut into it along with a mirror and a lamp to accurately measure the speed of light. Separating himself and the light by about 8 kilometers he rotated the toothed wheel until it went fast enough to block out the light from the previous opening in the wheel which allowed the light to pass through. Since he knew the distance and the speed of the wheel he accurately measured the speed of light within a few meters per second.
Before it was proven by Thomas Young that light traveled in waves just like sound it was believed that light was composed of particles (Newton's idea) which traveled through the "ether". Now we know there is no ether as it was presented and light travels in waves. Recently scientists were able to greatly slow the speed of light by transmitting it through an optically dense substance called Bose-Einstein Condensate. The Condensate is made up of atoms of rubidium cooled to almost absolute zero. There is a lot more information about bosons and condensates but most of them are far above the basics of physics needed to be known to understand how to measure the speed of light.
Albert Einstein's Theory of Relativity uses "c" to represent the constancy of the speed of light. It is now believed that light itself may be able to travel faster than the speed of light at least within light (not important for this discussion) and through experiments we have been able to slow down and even stop (freeze) light. But for all current and practical knowledge we believe that the speed of light through a non-vacuum is 3 x 10(8th) meters per second.
Galileo may have been the first scientist to try and measure the speed of light and he used a very rudimentary set of tools: two lanterns. He and an assistant separated themselves by about a mile Galileo would uncover his lamp allowing light to shine and as soon as his assistant saw the light from Galileo's lamp he would uncover his. Galileo judged this to be instantaneous. Well, he was almost right. It takes about 1700 billionths of a second for light to travel one mile.
Ole Roemer used the moons of Jupiter to prove that the speed of light could be measured (that it was not infinite). He noticed that when the orbits of Jupiter and Earth were closer he could see the moons of Jupiter much earlier than when Earth and Jupiter were at their farthest distance. In fact that amount of time turned out to be 16 minutes and 40 seconds though Roemer evidently held it to be 22 minutes and a few seconds. While Roemer did calculate the speed of light from these numbers he was actually of by 50%. Roemer calculated the speed of light to be 1.5 x 10(8th) meters per second - 1/2 slower than actual. The formula he used was to calculate the time it took for the light of Io to reach the surface of the earth in both the perigee and apogee of the orbits of Earth and Jupiter. Knowing the orbit of Earth to be 2 astronomical units he simply divided that time by the distance. He was wrong but he was on the right track. The year was 1675.
In 1849 we finally had the first non-space related measurement of the speed of light by a French physicist named Armand Hippolyte Louis Fizeau. Fizeau used a wheel with "teeth" cut into it along with a mirror and a lamp to accurately measure the speed of light. Separating himself and the light by about 8 kilometers he rotated the toothed wheel until it went fast enough to block out the light from the previous opening in the wheel which allowed the light to pass through. Since he knew the distance and the speed of the wheel he accurately measured the speed of light within a few meters per second.
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