For Your Viewing Enjoyment:
[img]http://i76.photobucket.com/albums/j19/t ... age001.jpg[/img]
[img]http://i76.photobucket.com/albums/j19/t ... age002.jpg[/img]
[img]http://i76.photobucket.com/albums/j19/t ... age003.jpg[/img]
[img]http://i76.photobucket.com/albums/j19/t ... age005.jpg[/img]
Dick
An Interesting Adjunct to Celestial Navigation
Moderator: Jim Walsh
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tartansailor
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Joe CD MS 300
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Oswego John
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Awesome - Thanks
Dick,
Thanks for submitting the post relating to the sizes of the planets, etc.
Someone, another member I think, sent the same post to me about a year or more ago. I well remember the initial shock and awe when I first scrolled that post.
I thought I had saved it but couldn't find it wherever I looked. You can bet that I'll take better care of this copy.
Thanks again,
O J
Thanks for submitting the post relating to the sizes of the planets, etc.
Someone, another member I think, sent the same post to me about a year or more ago. I well remember the initial shock and awe when I first scrolled that post.
I thought I had saved it but couldn't find it wherever I looked. You can bet that I'll take better care of this copy.
Thanks again,
O J
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Neil Gordon
- Posts: 4367
- Joined: Feb 5th, '05, 17:25
- Location: s/v LIQUIDITY, CD28. We sail from Marina Bay on Boston Harbor. Try us on channel 9.
- Contact:
At my age
That's why I always put Antares over the tip of the port spreader when heading home. The other ones are too hard to see without glasses.
Same for intergalactic travel, by the way... no sextant or paper charts required; it's more akin to piloting and dead reckoning...
"Just go straight for a few zillion light years, then turn left at Antares. You can't miss it."
(Note: Never give directions like "Turn left at the star by the Dunkin Donuts," or "Turn left at the star where the old space station used to be.")
Same for intergalactic travel, by the way... no sextant or paper charts required; it's more akin to piloting and dead reckoning...
"Just go straight for a few zillion light years, then turn left at Antares. You can't miss it."
(Note: Never give directions like "Turn left at the star by the Dunkin Donuts," or "Turn left at the star where the old space station used to be.")
Fair winds, Neil
s/v LIQUIDITY
Cape Dory 28 #167
Boston, MA
CDSOA member #698
s/v LIQUIDITY
Cape Dory 28 #167
Boston, MA
CDSOA member #698
Neil,
watch this comparison as an animation.
http://www.youtube.com/watch?v=EDNEV9EW06g
Ponder the big three question- What is the brightest star we can see?. What is the biggest star.? What is the closest star?
watch this comparison as an animation.
http://www.youtube.com/watch?v=EDNEV9EW06g
Ponder the big three question- What is the brightest star we can see?. What is the biggest star.? What is the closest star?
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Neil Gordon
- Posts: 4367
- Joined: Feb 5th, '05, 17:25
- Location: s/v LIQUIDITY, CD28. We sail from Marina Bay on Boston Harbor. Try us on channel 9.
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Pondering
Here's my best guess:Len wrote:Ponder the big three question- What is the brightest star we can see?. What is the biggest star.? What is the closest star?
The brightest you can see after sunset and before sunrise is Sirius. The sun would win during the day or if it doesn't matter if you can actually see it.
The Pistol Star is the largest known. No way to know what we don't know though.
The sun wins for closest whether it's day or night. Prozima Centauri is next.
Fair winds, Neil
s/v LIQUIDITY
Cape Dory 28 #167
Boston, MA
CDSOA member #698
s/v LIQUIDITY
Cape Dory 28 #167
Boston, MA
CDSOA member #698
It's the Sailstice!
Thanks, Dick, for showing those, they're very well done.
My astronomical observations for today are that the sun rose here at 7:32 (way too late), and that it just set at 4:12 (way too early).
From now on this situation will be improving, which is why I call it the sailstice - every day is longer and every one is a day closer to sailing!
My astronomical observations for today are that the sun rose here at 7:32 (way too late), and that it just set at 4:12 (way too early).
From now on this situation will be improving, which is why I call it the sailstice - every day is longer and every one is a day closer to sailing!
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tartansailor
- Posts: 1523
- Joined: Aug 30th, '05, 13:55
- Location: CD25, Renaissance, Milton, DE
Sailstice
Duncan,
You are right, the winter solstice;!
I completely forgot??
It's only getting better.
Here at La 38°49' Sunrise was 7::16 AM
and Sunset 4::43 PM
Best,
Dick
You are right, the winter solstice;!
I completely forgot??
It's only getting better.
Here at La 38°49' Sunrise was 7::16 AM
and Sunset 4::43 PM
Best,
Dick
sailstice - not as it seems
Speaking of astronomical things...
The latest sunrise and earliest sunset, depending on the observer's latitude, occurs anywhere from a few days after (sunrise) and before (sunset) 21 December to a few weeks after and before 21 Dec. The higher the latitude, the less the number of days difference. The shortest day of the year is still 21 Dec. At the Tropic of Cancer, the earliest sunset is about Thanksgiving, and the latest sunrise is about mid-January.
Without getting too deep into things, this occurs because the Earth's orbit is elliptical, and the Earth travels a little faster at one end of the ellipse than the other, which means the sun arrives at the meridian a little earlier in the day than it should on the "downside" of the ellipse and a little later on the "upside". The figure "8" that appears on some nautical charts, aka "analemma", is there to help navigators determine just how far ahead or behind the sun is on any given day of the year.
The latest sunrise and earliest sunset, depending on the observer's latitude, occurs anywhere from a few days after (sunrise) and before (sunset) 21 December to a few weeks after and before 21 Dec. The higher the latitude, the less the number of days difference. The shortest day of the year is still 21 Dec. At the Tropic of Cancer, the earliest sunset is about Thanksgiving, and the latest sunrise is about mid-January.
Without getting too deep into things, this occurs because the Earth's orbit is elliptical, and the Earth travels a little faster at one end of the ellipse than the other, which means the sun arrives at the meridian a little earlier in the day than it should on the "downside" of the ellipse and a little later on the "upside". The figure "8" that appears on some nautical charts, aka "analemma", is there to help navigators determine just how far ahead or behind the sun is on any given day of the year.
sailing to the stars
My three questions were very ambiquos- "see"--how ,when etc. While searching for a good answer I ran across an article on SOLAR SAILS that may get our "ships" into deep space.
Curiously, the sails are made of a new carbon based mateial (see below). Maybe this technonlogy can be applied to our earthly sails.
SPACE.com Exclusive: Breakthrough In Solar Sail Technology
By Greg Clark
A remarkable new carbon-fiber material is causing a revolution in the way scientists are thinking about laser and solar sails, according to engineers at NASA's Jet Propulsion Laboratory (JPL).
The fiber is a departure from solar sails of the past: it is about 200 times thicker than the thinnest solar sail materials, but so porous that it weighs the same.
"It's one of those things that comes along every so often that's kind of a technology breakthrough and at the same time, an honest-to-goodness paradigm shift," said Robert Frisbee, who analyzes advanced propulsion mission concepts at JPL.
"Always, I mean at least since the 1920s, people have thought of solar sails, laser sails, as basically being thinner and thinner sheets of solid material."
In space, solar sails would reflect photons of sunlight, thus harnessing their momentum. The sails, which could also be propelled by lasers, must be super-lightweight in order to benefit from the massless particles bouncing off their surfaces.
In addition, the sail surfaces must be tremendously reflective to maximize the propulsive force from the particles of sunlight.
Only in the past decade has it even been possible to manufacture sails that are thin enough, light enough and able to be coated with the proper reflective coating that sails require. But recent advances have finally made solar sails an option for certain featherweight spacecraft of the future.
Solar sails are now the propulsion method of choice for proposed NASA programs that strive to travel past the boundaries of the solar system, and to keep a gargantuan telescope hovering in space. Still, there is more work to be done.
The new carbon fiber mesh, which is developed by Energy Science Laboratories, Inc. in San Diego, California, could be the first step. The mesh is composed of a network of carbon fibers crisscross linked into a matrix that is mostly empty space. One hundred of these carbon fibers bunched together would make up a strand the size of a human hair
A piece of rigid carbon sail material, made by Energy Science Laboratories, Inc. "floats" in the air above a model's hand. At 3 grams per square meter, the fiber is 25 times lighter than standard copier paper. (Credit: ELSI)
The finished product, which is about as thick as the cover of a hardback book, is lighter than all but the thinnest plastic sheeting. Even the thin plastic that wraps a cigarette pack, or a batch of index cards is heavier than this carbon fiber material, said Tim Knowles, president of Energy Science Laboratories.
"You know how when you finally get that crap off the index cards, it's clinging to your fingers, and you've got to sort of shake your hand to get rid of the wrapping? Well, that stuff has an area mass of 15 grams per square meter," Knowles said. "Our stuff has an area mass of about 5 [grams per square meter]."
There are a few problems with traditional sail membranes: these sheets tear easily, they require a relatively heavy support structure to stretch them out and keep them tensioned, and they can build up static electricity. Moreover, ultraviolet light degrades these membranes and they melt easily at high temperatures, so they can never get too close to the sun. Another drawback: they can't be propelled by high-energy lasers.
However, the carbon fiber mesh is 25 times lighter than a sheet of typical office paper the same size, yet rigid enough that you can pick up a piece at one corner and the sheet will not bend, Knowles said.
"It's really my candidate for magic."
"We're making things that are 10 times lighter than that little plastic, but they stand in your hands like a stiff cardboard plate. You can take the material and then pleat it -- zigzag pleat it -- and then hold this sort of stack with your hand on the table," he said. "But when you move your hand, it jumps up like a jack-in-the-box, and falls flat on the table and you can't even see where it was creased."
The fabric is receiving tremendous notice because of its promise to self-deploy. Instead of having complicated and cumbersome deployment mechanisms to unpack and stretch out films in space, this carbon scrub-pad material could be packed so that it pops out flat once it is released.
"It's really my candidate for magic," Frisbee said. "Now we've sort of turned everything on top of its head… It's like in the cartoons when the little light bulb goes on over the guy's head. It's got people thinking in new ways about an old problem."
The carbon fiber is also a great leap because it can tolerate temperatures as high as 4,500 degrees Fahrenheit (2,500 degrees Celsius). This gives it a great versatility and durability that other materials lack, said Charles Garner, a JPL senior engineer who works with solar sails.
"The dream would be then you can make these ultra-, ultra-lightweight solar sails out of carbon fiber that can be either taken very, very close to the sun to get a big kick, or can be hit with large amounts of laser power or microwave power," Garner said.
Recent experiments at JPL have demonstrated that lasers can indeed push this carbon material, which glows hot orange and white from the power of the laser beam, but keeps its integrity as a sail.
Henry Harris, a JPL engineer who is managing research into laser and microwave propulsion, said the materials are a huge advance.
"We got the temperature of the sail up to 2,600 degrees Centigrade (4,712 degrees Fahrenheit), which is really good news," Harris explained. "What it means is that it's like any kind of engine: we can run the engine at much higher power levels than we had previously anticipated because we're using advanced materials. And so that has tremendous implications for the future of interstellar spaceflight."
Implications, Knowles said, that do not end with solar sails.
"When you see the stiffness of these things you don't have to limit yourself to thinking about sails. They can be antennas, they can be propulsion systems like sails, or they can be support structures for other things that a spacecraft needs," such as solar cells, or optical sensors, or even flexible electronics circuits, he said.
Curiously, the sails are made of a new carbon based mateial (see below). Maybe this technonlogy can be applied to our earthly sails.
SPACE.com Exclusive: Breakthrough In Solar Sail Technology
By Greg Clark
A remarkable new carbon-fiber material is causing a revolution in the way scientists are thinking about laser and solar sails, according to engineers at NASA's Jet Propulsion Laboratory (JPL).
The fiber is a departure from solar sails of the past: it is about 200 times thicker than the thinnest solar sail materials, but so porous that it weighs the same.
"It's one of those things that comes along every so often that's kind of a technology breakthrough and at the same time, an honest-to-goodness paradigm shift," said Robert Frisbee, who analyzes advanced propulsion mission concepts at JPL.
"Always, I mean at least since the 1920s, people have thought of solar sails, laser sails, as basically being thinner and thinner sheets of solid material."
In space, solar sails would reflect photons of sunlight, thus harnessing their momentum. The sails, which could also be propelled by lasers, must be super-lightweight in order to benefit from the massless particles bouncing off their surfaces.
In addition, the sail surfaces must be tremendously reflective to maximize the propulsive force from the particles of sunlight.
Only in the past decade has it even been possible to manufacture sails that are thin enough, light enough and able to be coated with the proper reflective coating that sails require. But recent advances have finally made solar sails an option for certain featherweight spacecraft of the future.
Solar sails are now the propulsion method of choice for proposed NASA programs that strive to travel past the boundaries of the solar system, and to keep a gargantuan telescope hovering in space. Still, there is more work to be done.
The new carbon fiber mesh, which is developed by Energy Science Laboratories, Inc. in San Diego, California, could be the first step. The mesh is composed of a network of carbon fibers crisscross linked into a matrix that is mostly empty space. One hundred of these carbon fibers bunched together would make up a strand the size of a human hair
A piece of rigid carbon sail material, made by Energy Science Laboratories, Inc. "floats" in the air above a model's hand. At 3 grams per square meter, the fiber is 25 times lighter than standard copier paper. (Credit: ELSI)
The finished product, which is about as thick as the cover of a hardback book, is lighter than all but the thinnest plastic sheeting. Even the thin plastic that wraps a cigarette pack, or a batch of index cards is heavier than this carbon fiber material, said Tim Knowles, president of Energy Science Laboratories.
"You know how when you finally get that crap off the index cards, it's clinging to your fingers, and you've got to sort of shake your hand to get rid of the wrapping? Well, that stuff has an area mass of 15 grams per square meter," Knowles said. "Our stuff has an area mass of about 5 [grams per square meter]."
There are a few problems with traditional sail membranes: these sheets tear easily, they require a relatively heavy support structure to stretch them out and keep them tensioned, and they can build up static electricity. Moreover, ultraviolet light degrades these membranes and they melt easily at high temperatures, so they can never get too close to the sun. Another drawback: they can't be propelled by high-energy lasers.
However, the carbon fiber mesh is 25 times lighter than a sheet of typical office paper the same size, yet rigid enough that you can pick up a piece at one corner and the sheet will not bend, Knowles said.
"It's really my candidate for magic."
"We're making things that are 10 times lighter than that little plastic, but they stand in your hands like a stiff cardboard plate. You can take the material and then pleat it -- zigzag pleat it -- and then hold this sort of stack with your hand on the table," he said. "But when you move your hand, it jumps up like a jack-in-the-box, and falls flat on the table and you can't even see where it was creased."
The fabric is receiving tremendous notice because of its promise to self-deploy. Instead of having complicated and cumbersome deployment mechanisms to unpack and stretch out films in space, this carbon scrub-pad material could be packed so that it pops out flat once it is released.
"It's really my candidate for magic," Frisbee said. "Now we've sort of turned everything on top of its head… It's like in the cartoons when the little light bulb goes on over the guy's head. It's got people thinking in new ways about an old problem."
The carbon fiber is also a great leap because it can tolerate temperatures as high as 4,500 degrees Fahrenheit (2,500 degrees Celsius). This gives it a great versatility and durability that other materials lack, said Charles Garner, a JPL senior engineer who works with solar sails.
"The dream would be then you can make these ultra-, ultra-lightweight solar sails out of carbon fiber that can be either taken very, very close to the sun to get a big kick, or can be hit with large amounts of laser power or microwave power," Garner said.
Recent experiments at JPL have demonstrated that lasers can indeed push this carbon material, which glows hot orange and white from the power of the laser beam, but keeps its integrity as a sail.
Henry Harris, a JPL engineer who is managing research into laser and microwave propulsion, said the materials are a huge advance.
"We got the temperature of the sail up to 2,600 degrees Centigrade (4,712 degrees Fahrenheit), which is really good news," Harris explained. "What it means is that it's like any kind of engine: we can run the engine at much higher power levels than we had previously anticipated because we're using advanced materials. And so that has tremendous implications for the future of interstellar spaceflight."
Implications, Knowles said, that do not end with solar sails.
"When you see the stiffness of these things you don't have to limit yourself to thinking about sails. They can be antennas, they can be propulsion systems like sails, or they can be support structures for other things that a spacecraft needs," such as solar cells, or optical sensors, or even flexible electronics circuits, he said.
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Neil Gordon
- Posts: 4367
- Joined: Feb 5th, '05, 17:25
- Location: s/v LIQUIDITY, CD28. We sail from Marina Bay on Boston Harbor. Try us on channel 9.
- Contact:
Solar sailing
Len,
These sails sound like they're only good for a downwind run. How do we get back?
These sails sound like they're only good for a downwind run. How do we get back?
Fair winds, Neil
s/v LIQUIDITY
Cape Dory 28 #167
Boston, MA
CDSOA member #698
s/v LIQUIDITY
Cape Dory 28 #167
Boston, MA
CDSOA member #698
I gotta have some of that
... when can I have one?
Re: Solar sailing
[quote="Neil Gordon"]Len,
These sails sound like they're only good for a downwind run. How do we get back?[/quote
Neil,
The universe bends.Keep sailing long enough you will come back to where you started. No need to come about!!
These sails sound like they're only good for a downwind run. How do we get back?[/quote
Neil,
The universe bends.Keep sailing long enough you will come back to where you started. No need to come about!!