BIKEPGH MESSAGE BOARD ARCHIVE

Brooke Pioneer Trail, W.Va description: "The first couple of miles of the Brooke Trail are out in the open and then it goes to mixed woods and sun. At MP 3.3 is the requisite sewer plant. At MP 3.9 is the start of an astronomical display with Neptune painted on the trail. The display ends with the sun at MP 6.9 with the remaining planets painted at their appropriate intervals." Is that something like what you're thinking of?

Sure, I think it would be cool to do. The planet walk on the Brooke Pioneer Trail is mentioned in the earlier thread (but called the Wheeling Trail planetwalk). Here's a page with some photos and other info. Theirs is 3 miles long from the Sun to Neptune, and it appears that to make the planets big enough to notice, they weren't painted to scale. Only the distances are to scale. Ours could be much bigger, and with planets to scale.

^yes. I think it would be cool to use the medallion at the fountain as the sun and scale it off of that - I think it's about three and a half feet or so. Or we could use the wall around the fountain (+100 feet?) and we would probably be able to go all the way to DC for Pluto. We could also mark the planets on the Ohio and Allegheny trails too - making the orbit circular unless someone wants to go to the complexity of figuring out the elliptical orbits.

You could use colored lines across the trails to designate the (mean) orbits of the planets, and a medallion set on the line in the trail to give the scale of the planet itself. With a plaque adjacent to the trail explaining the overall installation. That would be pretty mind boggling, to ride half-way to DC and see something the size of a quarter as a planet.

The Lehigh Parkway has one, on plaques, on the path. Here's a semi-informative URL: http://lvaas.org/staticpages/index.php?page=Planet_Walk&disp_mode=print

yes. I think it would be cool to use the medallion at the fountain as the sun and scale it off of that – I think it’s about three and a half feet or so. Or we could use the wall around the fountain (+100 feet?) and we would probably be able to go all the way to DC for Pluto. Using the medallion would give us a planet walk about the same size as the others. The inner planets would be much smaller than an inch (Mercury would be 0.15"), Jupiter would be four inches wide, and the whole walk would fit on the Jail Trail. Much of it would be within Point State Park. But if we used the whole fountain as the Sun (it's about 195 feet in diameter), then Pluto's average distance would be near Point of Rocks on the C&O. Its eccentric orbit would stretch from just north of Fort Frederick on the C&O, to a little past the end of the trail in DC. I like the idea of a really big model to illustrate a really big thing, taking advantage of our very long trail. Here's a map (same as in the other thread) using the whole fountain as the Sun. Here's a spreadsheet. You can edit it and put in your own diameter for the Sun, and it should fill in the scaled distances and sizes. Of course, a 100+ mile long thing isn't really a walk, it's more of a bike/hike. Pittsburgh Planet Bike? I guess we'd need permission to use that name. Pittsburgh Planet Trail? Great Allegheny Planet Passage?

Oooo I like the 195 foot sun! The Earth is about 21 inches big almost four miles away --- now that's scale. I wonder if we could get someone from the Science Center on board with this to give it some officialness. Edit: The Dahn'tahn Solar system; The Yins Orbiter

I like this project! I want to help with it.

There's one that starts outside the Air and Space Museum in DC that is on a one 10-billionth scale. Distance to pluto at that scale is 2000 feet. http://voyagesolarsystem.org/

Love the idea of a planetwalk. We could do both the large and small ones. There wouldn't be much overlap in the people who would see them. One would be for walkers or short distance bike riders, the other for long distance bikers. How can I help? I'm a bike enthusiast and an astronomer (CMU). I'm not sure what "officialness" I can lend, but there you have it. Do you need help building the installations, calculating orbits (um, that's not hard) or writing up blurbs for the trail markers? I like the idea that there would be a band across the trail at the point of the orbit and that we can make this go out in more directions than just one (up different bike trails). Good thoughts, all. How does one proceed with outstanding ideas like this? Is there funding available for materials? Do you work by committee? Thanks!

There's no committee as yet, no funding, just a bunch of people chatting on a message board. I think we need two main things, permission and funds. If we want a walkable-scale model, all within the city, getting permission would start with somebody talking to Friends of the Riverfront, and/or the city. If we go for a big model, we'd need to talk to the GAP folks for the outer planets. Neptune would be on the C&O Trail, run by the National Park Service. (I think we should just ignore Neptune until the rest is built.) For funds, we might start with the Carnegie Science Center and see if they'd be interested in supporting such a project. Even if they don't want to put any money into it directly, I think having some existing organization behind the project would make it much easier to get a grant for materials. As far as building it, what would we need? The inner planets are on asphalt, whether we built the big-scale version or the small one. So, paint to draw dots and lines, plus a URL (and maybe QR code) that leads to a project web site. We could probably do that much without a grant, just a Kickstarter-type project. With more funds, each planet could have a trailside sign, like the existing Friends of the Riverfront ones. I'm guessing those signs run at least a few thousand dollars each. The outer planets (using the bigger scale) are on crushed limestone (except Neptune, on dirt), so paint won't work. Those would need a sign. Perhaps it would be feasible to turn 8-20 feet of trail at those points a different color of limestone, to show the size of each planet. (Of course, if we used a smaller scale suitable for walking, say one mile to Neptune, all the planets would be on asphalt, but the inner ones would likely be too small to notice on the ground. They would need to be a dot on a sign, about a tenth of an inch in diameter.) Does anyone here know anyone at Friends of the Riverfront, or at the Carnegie Science Center? If not, perhaps Diane would be the best person to contact the CSC?

I agree with Steven's synopsis. One thing to add. If a sign or plaque were installed at each orbit location; it would be cool to have a grade school adopt-a-planet and determine what facts to put on it. It might even encourage a yearly bike ride. Obviously this would be easier to coordinate if the CSC were involved.

I rather like the idea of the large-scale model. It allows for us to say Voyager 2 is in Virginia Beach VA or Hartford CT or some such. Which in itself is cool, in that it makes Pittsburgh the center of the known universe.

Whatever you decide to do, I believe you're going to need to coordinate with someone in the State Park system for permission to install something at the Point. For the C&O you're going to be dealing with the Nation Park system. Might be more red tape involved than anyone initially figured. How about approaching a politician with the idea? You might need to get one of them to help. I also think that getting the Science Center behind it would carry some weight. You should probably contact Linda Boxx with the idea too. Not only would you want her involved for anything regarding the GAP, but she could probably advise and/or help with who to talk to about the C&O. I'm sure that each local trail council where you want to mark/display a planet is going to have to have a say in it too.

Good ideas, thanks all. I just sent the email below to Friends of the Riverfront, the Carnegie Science Center, and the Allegheny Trail Alliance. I'll let you know when I hear back. Greetings. I'm one of a group of Pittsburgh cyclists who have been discussing the idea of building a scale model of the solar system along the Great Allegheny Passage from Pittsburgh. We think this would benefit the region, both as an educational tool, and as a point of interest for all trail users. We're starting to contact appropriate local organizations to gauge interest or support for the idea. Can you let me know who at your organization would be the best person to contact to discuss this idea, or forward this email to them? Several other trails have such scale models, but the GAP provides a unique opportunity to construct a model on a considerably larger scale. There are major advantages to such a model, though it presents unique challenges too. Most solar system models of this sort either accurately represent the distance between planets, or the relative sizes of the planets, but not both. The problem is that if you choose a scale that keeps all the planets inside a typical park, or on a short stretch of trail, then the inner planets, if constructed to scale, are too tiny. For example, a trail near Wheeling WV has such a model. Their Neptune, a simple circle painted on asphalt, is 2.8 miles from their Sun, using their scale of 1:1 billion. But at that scale, Neptune would be a circle just 2 inches in diameter. Earth would be a dot just half an inch in diameter. So the trail abandons its interplanetary scale and uses larger circles to represent the planets, so they'll be easily visible. The relatively small size of their trail requires this compromise. But imagine if Pittsburgh's iconic fountain at Point State Park represented the Sun, and the trail stretched out along the Great Allegheny Passage. At that scale, Earth would be a circle almost 2 feet wide, located on the Baldwin Borough Trail near Becks Run Road, an easy ride from downtown Pittsburgh. A huge planet like Jupiter wouldn't be represented by a small dot, but a circle 20 feet wide. The inner planets would all be in easy biking distance of Pittsburgh, with the remainder stretching out toward Washington on the GAP (with Neptune located on the C&O). This scale represents the great distances to the outer planets on a scale that's easily understandable, yet still makes them seem appropriately far away. That's one of the possibilities we've been discussing. We're still talking about what materials might be used (paint on asphalt, signage, web site, etc.), which organizations would need to give their permission for such work, and how the project might be funded. Our informal group includes volunteers with expertise in everything from astronomy to web design, so we'd like to start talking to organizations like yours to get a better idea of our next steps forward. Thanks in advance for any pointers or suggestions.

+10 (Sun + 8 planets + Pluto) Edit: Can we add a rock garden of some sort for the Asteroid Belt?

Well, a "rock garden" done to scale, would be more like a sand garden.

Some sand, but Ceres (the biggest) would be 1.6 inches in diameter on the fountain-as-Sun scale. The other bodies would all be under 1 inch in diameter, though there would be hundreds or maybe thousands of them bigger than a grain of sand. (The maximum size of a grain of sand is 2 mm, which corresponds to an asteroid diameter of around 50 km.) But how do we best represent a region that's still mostly empty space, even if it's got a bit more stuff in it than the surrounding regions of even emptier space? Plenty of movies like Star Wars show spaceships navigating through dense clusters of rocks, dodging dozens of whizzing asteroids. It would be good if our model served as an antidote to that, showing how you can go right through it and almost certainly won't even notice it's there. (Wikipedia mentions collision odds during a trip through the asteroid belt of under one in a billion.) Do we just show a few of the biggest asteroids, widely scattered over perhaps 8 miles of trail? Does that convey how extremely sparse they are?

This is where the project gets interesting. I think it's useful to have some representation of where the Asteroid Belt is, in relation to Mars and Jupiter. But physically, how to do that? I was envisioning a couple of benches alongside the trail with some gravel around them, and a sign. Geographically, it looks like it could end up somewhere around Boston. But this is where the fields of astronomy, architecture, and art all intersect. Also I like how (coincidentally?) both Jupiter and Saturn are in or close to fairly large towns (West Newton and South Connellsville, respectively), which helps the cause. Putting Pluto at Mile 0, or as close as feasible, also has its attraction. Having it there might drum up interest in the trail itself, and what's on the other end.

Because orbits are elliptical, there is a range of places any one body can be placed with respect to the fountain and still be accurate. This should allow for more interesting placement.

Sure, and the asteroid belt in particular is really wide. I found one source that says it's from 2 AU to 4 AU, or from Kennywood to Buena Vista. It might be interesting with the planets to show how elliptical the orbits are, with markings for the closest and farthest points. Venus and Neptune aren't nearly as elliptical as Mercury, for instance. But I'm not really sure how many details like that we'd want to include. Does it become too much to absorb at some point?

I think the simple stuff we keep to a sign at a single spot on the trail, and the complex stuff we put on a website, using a QR code on the sign to take you to the website. Let's let the astronomers come up with the bright ideas there. I'll just speak as the geeky kid who sat in the library decades ago, poring over Herbert S. Zim books, memorizing tables. Earth=93M miles, Mars=141M, etc. If we can get the general public to understand even that much, we've done our job.

I learned about this thread yesterday from a colleague here at CMU, who informed me because she knows I am working on an extension to the Sagan Planet Walk, an existing project centered in upstate New York. Here is an excerpt of my reply to her. All calculations are back-of-the-envelope: Steven says the Sun would correspond to the fountain at Point State Park, which a quick website search suggests is about 200 feet in diameter (about 61 meters). Another quick web search has the diameter of the Sun at 1.4 x 10^9 m -- so the proposed scale model is approximately 23 million-to-1. Earth is therefore about 0.55 meters, or 1.8 feet across, as he indicates. The distance between Earth and Sun would be approximately 6.5 km, or 4 miles. At that scale, the Carnegie Science Center is close -- too close, unfortunately. As the crow flies , it's 0.392 miles away from the fountain, which corresponds to about 9,000,000 miles. Even at perihelion, Mercury is more than 3x farther away. I'm interested not only in length (body and distance) scales, but also time and velocity scales. A few quick observations: 1) The speed of light is 300 million m/s, which scales to 13 m/s, or 30 mph. Again, I'm not a cyclist; there are road safety issues; and the scale model is straight-line distance, not road distance. But I can imagine a "light speed" race that would require someone to hit an average of 30 mph for 4 miles, maintained for 8 minutes. That would represent the speed of a photon emitted from the Sun's surface to the Earth. [Today I saw the previous thread from a few years ago had also mentioned the speed of light.] 2) Voyager 1 is traveling at approximately 62,000 km/h, or 17,000 m/s. At scale, that's only 7.4 x 10^-4 m/s, or 0.0017 mph. I wish I could think of a good comparison for that. suggests it is 90x slower than a sloth, or 10,000x faster than grass growing. It would be interesting to represent Voyager 1, including occasionally moving its monument marker to represent its real-life motion. 3) Another possibility is to actually have the planets in motion around Point State Park. But they would move rather fast -- 108,000 kph corresponds to 0.0047 kph at scale. This is more than 100 meters every day -- it would require an extraordinary commitment to move the planet markers every day! [Today I saw the previous thread mentioned several representations for each planet -- this makes better sense.] 4) Of course there's also the possibility of placing something on the Moon. [This statement refers to art projects I am designing for launch in 2015.] That would be about 8.8 x 10^15 m away -- just a little under a light year, at the 23 million-to-1 scale. Perhaps this could represent the edge of the Oort cloud. I think the speed of light at ~30mph and the Oort cloud at lunar distance are the most interesting. Let me know if I can help.

A projected image of the above, over an image of the square mile or so of the Point, on a website, is a lot easier to portray than moving three-dimensional objects.

Great post, William Alba! Wonderful! William Alba: 2) Voyager 1 is traveling at approximately 62,000 km/h, or 17,000 m/s. At scale, that’s only 7.4 x 10^-4 m/s, or 0.0017 mph. I wish I could think of a good comparison for that. suggests it is 90x slower than a sloth, or 10,000x faster than grass growing. That seems just about the right speed for my riding! Now Business: When and where can some of us meet to start this thing going? How about ane evening next week? Is Tuesday, May 13th good? I can't really make it before 7:30. Place? How about the Big Dog Coffe shop at 2717 Sarah St? That was the place where flock reorganized at some point. I would have no objection to leaving the Big Dog coffe shop behind for the convience of the big dog science geeks at CMU - or any other place that I can get to from work at my standard .0017 mph. Pros and cons for any of this are highly encouraged! (I'm just making this up as I go along.)

Yes, I think Voyager's position, and the speed at which the planets revolve around the Sun, might be better conveyed on a web site. As Stu mentioned, Voyager 2 is as far off as Virginia Beach VA. I think getting them to put up a moveable marker (or putting something on the Moon!?) is beyond where we should be aiming for now. But I can imagine a time-lapse video on a web site, showing Point State Park with animated planets circling around its fountain as the sun (the real one) rises and sets, as a way of presenting orbital velocity. Or perhaps a sped-up Gopro-type video of a trip along the GAP, with animated planets drawn on top (maybe as a demo for presenting what we want to build). Tuesday 5/13 works for me, any time in the evening, any place. Monday or Wednesday that week would also work. (But I'm not sure what a meeting would accomplish that can't be done more easily online.)

As Stu mentioned, Voyager 2 is as far off as Virginia Beach VA. I think getting them to put up a moveable marker (or putting something on the Moon!?) is beyond where we should be aiming for now.

I agree the logistics of representing Voyager on the Earth might be difficult. I wonder... if Voyager 2 corresponds to Virginia Beach or Hartford, would Voyager 1 (which hasn't traveled as far) be near Ithaca, New York? I am working with some folks at the science museum there, so if we move forward, I'd be happy to raise the possibility. Because I am already sending other projects to the Moon, placing an object there might actually be easier to implement (!) than coordinating with folks in Virginia or Connecticut. However, I want to avoid sending a mixed message -- the Sagan Planet Walk, which I already plan to extend to the Moon, is a 5 billion-to-1 scale model, and it's somewhat confusing to simultaneously extend a 23 million-to-1 model. I'd be happy to meet anytime on this. Note that CMU is rife with end-of-academic-year business, and this Tuesday I am in meetings almost non-stop from 9:30am to 5:30pm. It might be better to continue discussing on this forum for now, as Steven suggested. Then again, I'm a complete newcomer non-cyclist, so just let me know how I can help.

This is the ideal message board project. It's all ideas at this point, and maybe some behind-the-scenes lobbying and paperwork. I don't see any pressing need to meet face to face, at least not anytime soon. When I said Hartford or Va-Beach, I was merely throwing a dart at the map. The idea was, the two Voyagers are beyond the other end of the GAP/C&O trail, so I picked a couple of plausible locations up and down I-95, rather than saying "n nautical miles out in the Atlantic". Something visualizable by the common man. Think web sites, which you can get to via a QR code from your phone along the trail. Or which can be an easy click or two while sitting in a classroom. And ways to make those concepts easy to wrap your head around.

Little marker for Voyager on teh Appalachia trail? Maybe some of the extensive WV bike trails? Think of it this way - "The meadow river - the final frontier." it will be a while before Voyager moves much.

Back on May 1, I sent the email shown above to Friends of the Riverfront, the Carnegie Science Center, and the Allegheny Trail Alliance. The Program Manager at Friends of the Riverfront sent my email on to their Executive Director back in May. I never got a response back. She tried again on June 9. I still haven't heard anything back, and just emailed her again. The Assistant Secretary/Treasurer at the Allegheny Trail Alliance sent the idea to several of their board members, who wanted details on implementing and maintaining the project. One said they might be willing to consider it if the Carnegie Science Center was on board and there was a more detailed proposal. I sent them some notes on an inexpensive implementation (a small simple sign for each planet, leading to a web site, paint on asphalt trail for the inner planets), how it might look with more funds (coloring the crushed limestone trail surface for the outer planets, bigger interpretive signs throughout), and so forth. Haven't heard back yet. I've sent multiple emails to various people at the Carnegie Science Center, and have not had any reply at all. I'm going to try calling them this week.

Cincinnati has a geologic timeline something like this idea, along its riverfront walkway. The timeline covers 450 million years of earth history and each square covers one million years. http://queencitytour.blogspot.com/2013/03/geologic-time-line.html

Steven - anything I can do to help this along?

Thanks, but right at this point I think there's just waiting for the various organizations to digest the proposal and respond. Today I spoke to Brendan Mullan, the new director of the Buhl Planetarium at the Carnegie Science Center, about the project. He sounded interested, but thought funding would be hard. I followed up with a long detailed email proposal, focusing on a cheap crowd-funded implementation at first, with fancier stuff later. The response from Friends of the Riverfront, as it turns out, was to forward the proposal to the Allegheny Trail Alliance, which I'd already contacted directly. I'm currently waiting for a response from the ATA to the detailed proposal I sent them last week. So I think the ATA will need to be on board before FotR gets involved, and probably likewise for all the other local trail groups that operate different parts of the GAP. And it would help convince the ATA if the Carnegie Science Center were on board in some capacity.

Here's the detailed email I sent to Mr. Mullan today: It was good talking to you today. As I mentioned, I'm one of a group of Pittsburgh cyclists who have been discussing the idea of building a scale model of the solar system along the Great Allegheny Passage bike trail that extends from Pittsburgh to Cumberland MD. We think this would benefit the region, both as an educational tool, and as a point of interest for all trail users. We're starting to contact appropriate local organizations to gauge interest or support for the idea. Several other trails have such scale models, but the GAP provides a unique opportunity to construct a model on a considerably larger scale. There are major advantages to such a model, though it presents unique challenges too. Most solar system models of this sort either accurately represent the distance between planets, or the relative sizes of the planets, but not both. The problem is that if you choose a scale that keeps all the planets inside a typical park, or on a short stretch of trail, then the inner planets, if constructed to scale, are too tiny. For example, a trail near Wheeling WV has such a model. Their Neptune, a simple circle painted on asphalt, is 2.8 miles from their Sun, using their scale of 1:1 billion. But at that scale, Neptune would be a circle just 2 inches in diameter. Earth would be a dot just half an inch in diameter. So the trail abandons its interplanetary scale and uses larger circles to represent the planets, so they'll be easily visible. The relatively small size of their trail requires this compromise. But imagine if Pittsburgh's iconic fountain at Point State Park represented the Sun, and the scale model stretched out along the 150 mile Great Allegheny Passage. At that scale, Earth would be a circle almost 2 feet wide, located on the Baldwin Borough Trail near Becks Run Road, an easy bike ride from downtown Pittsburgh. A huge planet like Jupiter wouldn't be represented by a small dot, but a circle 20 feet wide. The inner planets would all be in easy biking distance of Pittsburgh, with the remainder stretching out toward Washington on the GAP (with Neptune located on the C&O). This scale represents the great distances to the outer planets on a scale that's easily understandable, yet still makes them seem appropriately far away. Exactly what this would look like would depend on funding. The project could be approached in stages. The initial minimum-budget version would be entirely funded with a Kickstarter-type donation campaign, and use volunteer labor and donated materials as much as possible. If that sparked sufficient interest in the community, we could improve the elements and make additions. The project could include these elements: 1. Given the scale we're proposing, with the Point State Park fountain as the Sun, then Mercury, Venus, and Earth would be located on asphalt trail surface (Earth on the Baldwin Borough trail not far from Becks Run Road, the others on the Eliza Furnace trail). Diameter of each planet would range from 8 to 21 inches. These would be rendered as painted circles on the asphalt surface. Each would be accompanied by a sign on the adjacent wall or fence, displaying at a minimum the project name (such as Allegheny Trail Planet Walk -- the actual project name is TBD), the name of that planet, and a URL and perhaps QR code so trail users could find more information on the web. A project web site would then have a page supplying details about that planet and about the project, a map showing the other planets, and so forth. Ideally, we'd also develop an app that would provide the same info as the web site, but in a form that users could bring along on their smartphones or tablets to locations without Internet access. Our group includes various people with web design and software development expertise, so we expect the web/app component would be straightforward, with all labor donated and few or no expenses. 2. A similar sign for the Sun would be located near the fountain in Point State Park. As far as making the signs, our bicycle community includes various people with expertise in metalwork (making bicycles, for instance), so it's possible we could get long-lasting metal signs made with donated labor and perhaps materials, for this minimal-budget version of the project. Or perhaps they could be more like the plastic lawn signs used in political campaigns, replaced as needed. We'd need to look at the tradeoffs between longevity, cost, and how much info we could put on each type of sign. (With a bigger budget, we might have signs similar to the existing historical interpretive signs and maps that Friends of the Riverfront has installed along the riverfront trails. But that would likely be only in a later stage of the project, and I imagine it would require a grant or corporate sponsorship or something of that kind.) 3. Mars would be located on the Steel Valley trail, on the crushed limestone segment at the Homestead Waterfront. At just 11 inches wide, I don't see a practical way to draw it permanently on the crushed limestone trail surface. So perhaps a round 11" diameter trailside stone marker could be installed in the ground. Or perhaps the sign affixed to the adjacent fence could merely include an 11" circle to represent the size of the planet, or an 11" diameter ball could be fashioned and secured to the fence. 4. The outer planets Jupiter (near West Newton), Saturn (near Connellsville), and Uranus (near the Big Savage Tunnel) would all be on crushed limestone trail surface, and range from 7 to 20 feet in diameter. We're hoping it will be possible to represent them by coloring the trail surface, perhaps by mixing crushed limestone with some darker type of crushed stone and spreading that on the trail for a distance of 7 to 20 feet, or by applying a paint or dye to the limestone. We'd start by contacting users of other trails around the world to see if there's some existing, proven technique for coloring a crushed limestone trail surface, something that results in a good riding and walking surface, is safe around animals and plants, and lasts. But it might require some experimentation to get right. These three sites would each be accompanied by a sign, like the others. Since two of the three sites are luckily quite close to towns, we're hopeful that many trail users with smartphones will have Internet access at these sites. Still, more elaborate and self-contained signs would be particularly welcome at these more remote locations, if our budget permits them. 5. , Neptune would be near Fort Frederick on the C&O Canal Trail, the only representation not on the Great Allegheny Passage and not in Pennsylvania. For now, we're planning to ignore an on-the-ground representation here, since there are some unique issues with its location inside a national park, and the dirt trail surface. Once the remainder of the project is complete, we could approach the National Park Service and ask what could be done at that site or nearby. (The adjacent asphalt-paved Western Maryland Rail Trail might serve as a substitute location, if necessary.) Of course, the specific components we choose will depend on available funding. The initial simple crowd-funded project could be eight signs (Sun plus Mercury through Uranus), some paint for the asphalt, and a web site, something we could manage for a few hundred dollars, I think, using all volunteer labor and purchased plastic lawn signs fastened to fences or trees. We'd hope that implementing that part would lead to some publicity and then donations to fund the subsequent steps. The next one might be crafting a stone or ball to accompany the sign for Mars. Then we'd figure out how to color a limestone trail surface to represent Jupiter, Saturn, and Uranus, to accompany those signs. Finally we'd talk to the National Park Service or the Western Maryland Rail Trail folks about adding something there. Along the way we'd hope to improve the signage, perhaps replacing inexpensive plastic signs with more long-lasting ones. We've also discussed other elements we might consider one day representing on-trail in some fashion, such as select moons, the asteroid belt, indications of the aphelion and perihelion of each planet's orbit, and so forth. These are rough concepts, of course, and we'd welcome suggestions on any aspect. Here's a map showing the location of the planets along the trail. Here's a spreadsheet in Google Docs showing the calculations for location and size. I'm hoping the Carnegie Science Center would be willing to offer advice on this project. For instance, if you could look at the sign designs before they're printed and suggest ways they could communicate more clearly, or make suggestions on the web site, that would help. (Of course, if the CSC wanted to be even more involved, say helping to design the signs or web site, I'm sure we'd welcome that too.) And simply being able to tell trail groups that we're working with the Carnegie Science Center on the project would be a huge help in obtaining the necessary permissions from local trail organizations to paint and sign the trail. Thanks for reading this. Hope to hear from you soon.

Steven – anything I can do to help this along? On further reflection, there are some things that'll need doing, so if you're interested: 1. I suggested that our cycling community includes folks with metalworking expertise, and we might be able to sweet-talk some into volunteering to make signs. That was on the basis of seeing discussions of welding and such on the boards. I know nothing more about that though, and can't remember who was involved. But it would help if we had some ideas or estimates for making signs of various types. I see lawn signs run around $20 each. How about metal ones? Who has expertise in this? 2. I suggested that we could look for other trails that have colored their crushed limestone, and see how they did it. Want to research this and ask around?

Status update: Brendan Mullan, the new director of the Buhl Planetarium at the Carnegie Science Center, is now on board, and we can use their backing as we talk to other groups. I'll be talking to the ATA again to work on the permission angle (since one of their board members hoped to see the CSC involved before seriously considering the idea). Both Mr. Mullan and the ATA want to see a detailed budget, so I've been working on that, along with a writeup of how the project might be done. That's here. Comments welcome. I'm still trying to get prices on a few items, in particular, an 11.4" diameter round *something* to represent Mars. One option I thought of was using a 3D printer to make a custom plastic ball of the right size, but I don't know how much it would cost. Anyone want to supply an estimate? Any other ideas for this? I'm now thinking that buying signs would be simpler than asking volunteers to make them. But I'd still like help with finding other trails that have crushed paths in different colors.

Wow, outstanding write-up Steven! I hope with CSC involvement maybe we can actually pull this thing off. One thing not mentioned though is the option to get school kids involved with designing markers or web pages. I bring this up because it would be consistent with CSC's educational mission & it may also help bring in foundation money (?). Of course it also adds to the complexity of the project...

Thanks! Yes, I thought the added complexity and delay wasn't worth it for the first, crowdfunded phase, where we're not dependent on the CSC or anyone else for funding. If the CSC or a foundation wanted to fund a future phase with fancier replacement signs, and wanted to use their resources to have schools participate, cool. But it looks like such funding is not an option at this stage, schools or no schools.

Second the "outstanding write-up", Steven! You've done a lot of work on this. Couple of possible suggestions: on the paved segments, maybe do the planets like they did the Toynbee Tiles?? http://en.m.wikipedia.org/wiki/Toynbee_tiles They seem to last a long time, shouldn't cost much, and would be easy to ride/walk/run over. On the limestone segments, could we outline them by embedding bricks into the trail so that they're flush with the surface, and then fill in with something?? Does anyone know if crushed lava rock would make a suitable surface? Maybe the better option would be to just use embedded brick for the whole image. Again, not very expensive (less appealing for vandals/thieves), easy to ride over, durable. Maybe we could enlist the aid of some of our local artists to paint the signs? Or - maybe that's where we could get some kids involved. Give them the info that we want on the sign along with the format we want it in. Let them paint the planet image on top and hand paint the statistics. Leave the bottom right corner blank and we add a QR code there later.

Thanks. I love your Toynbee Tile idea, but I see some possible difficulties. One issue is that the adhesion process might depend on cars rolling over it. The Wikipedia page offers that as one theory. It might also be challenging to get the small quantities of linoleum and vinyl composition tile needed at a reasonable price. This article suggests checking salvage lots and such. I'm not sure how to budget for that. Finally, do these designs expand or deform as they bond with the asphalt? That would complicate making a properly scaled circle. The end result could be much better than painting, though. I added it to the plan as a possible alternative. I think it would require a test run first, at some innocuous non-car location, since it's not something we could easily remove, and having wrong-sized-Mercury embedded in the pavement next to real-Mercury would be unfortunate. :-) Would you be interested in working on this? At this stage, that would mean finding and pricing materials. I found asphalt crack filler and tar paper so that leaves linoleum and vinyl composition tile. I also added your idea about bricks to the plan. I've got an email out to a landscaping company asking for ideas, too. But that part's not until phase 2, so there's no rush.

Found a source for linoleum. Rusmur Floors still sells it.

Toynbee tiles! Awesome!

That's great! Do they have a range of colors? For Mercury and Venus, solid circles in the yellow-orange-light brown family would work OK. but it would be great if we could get blues and greens for Earth. How much would it cost from them if we had to buy it and couldn't get donated scraps? Latest project news: The ATA board is considering the project, and I hope to hear back soon (many of them have been on vacation). Making a right-sized ball for Mars via 3D printing appears to be cost-prohibitive. Getting an 11.4" diameter ball made of painted wood or maybe metal might work OK. Maybe one of those "maker fairs" would be a good way to find someone with the appropriate skills and tools.

NASA/Goddard Space Flight Center has joined with the Friends of Anne Arundel County Trails to create a project that will enable the County's residents to stroll, bike or rollerblade through the solar system: http://www.americantrails.org/resources/art/planetwalk.html

We were on the Brooke Pioneer Trail a couple of days ago, and riding over their planetwalk reminded me of this thread. This is a great idea -- let's keep the project going. Thanks, Steve, for all the planning work. I particularly like the idea of making it a regional project, or at least a regional opportunity. Yes, get the Great Allegheny Passage on board for the first complete set -- but provide the detailed orbits overall (plus standard sign design) so that other trails, parks, schools, and anyone else with land at an appropriate distance from "The Sun at The Point" could lay down a marker. Consider this when choosing a name -- perhaps Western Pennsylvania Planetwalk" (Planetride? Planetmap? Solarmodel??)

Thanks! Picking a good name isn't easy. I like including "Western Pennsylvania" to make it more regional, though not all the planets would be in PA. I haven't heard back from the ATA board yet, and sent the ATA another followup email today. Thanks for the reminder!

Just ran across an online version. It's based on the idea of making our Moon 1 pixel in diameter. http://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html This really drives home the great emptiness of the solar system

OK, the ATA got back to me this week. They didn't have anyone there volunteer to be a liaison, and therefore they don't plan to have any direct involvement. But they think it's a great idea, and encourage us to work directly with the individual trail groups. I originally contacted Friends of the Riverfront, who sent me to talk to the ATA instead, which has now suggested I talk to FotR and the other groups. So now I'll go back to FotR and see what they say.

@steven, when you approach the local trail groups, tell them that the Trail Volunteer Fund (http://they-working.org) is interested in helping, assuming that most of the work is being done by volunteers and the trails are willing to have the markers installed. The volunteers don't need to be members of the various trail groups, they can be interested only in this project (that is, the project doesn't necessarily drain the trails' own volunteer pools).

Thanks, that's great to hear! A followup from the ATA explained that while they won't have direct involvement, they have final approval on all trail signs (once the local trail group approves of them), and have a very detailed list of rules and requirements for them, from fonts and colors to bolt types. I suspect this means all the sign prices in the proposal will need to be revised upward quite a bit. But on the other hand, the result should be long-lasting quality signs.

It's reasonable for ATA to have design standards for signs to keep the trail from becoming a total hodgepodge. I've seen their design standard, it's generally not unreasonable. When you talk to Friends of the Riverfront, consider taking a map with full orbits. Friends covers all the city riverfront trails, and the inner planet orbits will intersect along the Allegheny and Ohio as well as the Mon. By casting this as a regional planet model, we distinguish it from most of the trail planetwalks because it's 2-dimensional rather than 1-dimensional. This should be especially interesting to Fiends, because it hits their three major trail segments. As to price -- the permanent signs should be permanent. However, if there's uncertainty about the "feel" of the layout, we could print up some signs on coroplast and put them up on a temporary basis, much as signs for events are put up for just a week or two. Oh, and if you can figure out a reason the sun should be 205 ft in diameter, we can put Earth in our front yard. Even picking a round-number scale of 1:22,500 (which implies a sun diameter of 202.9225+/- ft and is easier to explain) would put us inside the maximum Earth orbit.

Only vaguely related to the project, but a great way to visualize the relative size of a few objects, is this story I ran across today. We did not talk much about placement of various moons of the planets on this project. Seems do-able, but a considerable level of complexity beyond getting it done at all.

Afraid I haven't had the time to do anything on this project since January. I guess the next step is going back to FotR with what the ATA said.

I rode Baltimore-Annapolis this weekend and took video of the inner planets and the sun in their solar-system-display. The perspective is from Earth to the Sun. https://youtu.be/YRyMtONWd3k Then I found this, a list of 30 "Planet Walks" http://pillownaut.blogspot.com/2012/06/solar-system-hikes-in-america.html

I didn't see the Planet Walk/Bike near Wheeling, WV listed...

Here's a desert model of the Solar System using a marble for the Earth: http://www.theatlantic.com/video/index/417309/our-place-in-the-universe/ In the comments there, someone mentioned a "Cycle the Solar System" model along a bike path in York, UK. They put models of each planet, to scale, on pedestals along the bike trail. Pluto (which they included), is 10km out. Earth is 2 cm in diameter. "The Sun is made from 2 fibreglass hemispheres manufactured for a septic tank." "The speed of light is about 1.16 mph, so it is easy to walk at around 3 times the speed of light and to cycle at about 10 times the speed of light." https://www.york.ac.uk/solar/index.html

The one along the trail between Weirton and Wheeling is just paint on the trail -- but it's there. We can make ours distinctive by publishing the orbits and inviting interested parties close to each orbit to install their own planets. This also helps include all the trails that spread out from the Point -- we don't have to choose one, we can mark the orbits on all the trails.