27 November 2005
| Observing Location | New York City |
|---|---|
| Observational Period | |
| Atmospheric Conditions | Need I say more. |
| Instruments | |
| Observing Party |
Although the weather is the pits I did get some astronomy done.
I went down to RadioShack, which is in one of the buildings attached to mine, and bought replacements for all of my dead batteries -- the red dot finder and the digital caliper.
I Create the Solar System in Under 7 Hours
Yesterday I was thinking about our newfound brother, Quaoar, and wanting to visualize where he was. When I got into mapping I always wanted to crate my own map of the solar system with all of the planets shown to scale but could never pull it off. The small planets were just too small and the distances just to great. A couple of weeks ago, while at the public observing session at Columbia University, it came to the fore again when a smart kid was looking at Planetarium on my Palm and figured that I could do his homework for him and tell him how big the planets are. Then yesterday while searching the Web to find out how to spell orrery I came across a project to build a model solar syste, to hang from a classroom ceiling. It piqued my interest again.Somewhere along the way I came across a Java applet (or maybe it was JavaScript) that calculated the size and distance to all of the planets based on the size you told it to make the sun in inches. There was a downloadable text file that was supposed to open in any spreadsheet so I downloaded it. I tried to open it with StarOffice and nothing happened. I could load it into Excel, but all the important formulas were broken. But I was able to see enough to create my own spreadsheet.
My concept was to be able to create a solar system at a scale that we can understand. I wanted to that if the Sun was the size of a basketball the Earth would be the size of a baseball and would be so many feet, blocks or miles away, whatever. I found in working with the spreadsheet that it ain't quite that simple. At convenient Sun sizes Mercury disappears. By experimentation I found that if I created a Sun 7” in diameter then Mercury would be about 0.25” in diameter. So Mercury would be large enough to relate to, about the size of a pea, but the Sun would be 7” in diameter and I don’t know of any ball that is 7” in diameter. And when you get out to Pluto and Quaoar they are both smaller than grains of salt. But at least I had the Solar system in a humanly understandable scale for diameter.
The spreadsheet also scaled the mean orbit down to feet. But what does 482 feet look like. I know that my pace is 5 feet, and I know that there are 20 blocks to a mile walking uptown and 10 to a mile across town (your mileage may vary). That was my a-hah moment. Relating orbits to distances from a familiar point was the key.
I modified the spreadsheet to calculate the distance in blocks. So I started searching the Internet to find out how long a “standard” NYC block was. The closest I could find was a page that said there are “about” 20 blocks to the mile going north/south. That was going to have to do. I did the maths and came up with the number of blocks an orbit represented. Then I entered the starting point for the Sun as Columbus Circle (59 St) and it said Quaoar was up at 238 Street in The Bronx. That wasn’t very helpful since you usually don’t walk from Manhattan to The Bronx, and the streets are at funny angles up there so the spatial relationship might not apply. Next I tried Times Square (42 St) and Quaoar was still too far north. Finally I settled on 1 St which brought Quaoar back onto Manhattan Island. I ended up with the following table of diameters and orbits.
| Planet | Actual Diameter |
Scaled Diameter |
|
|---|---|---|---|
| kilometers | inches | Representation | |
| Sun | 139,100 | 7.00 | |
| Mercury | 4,880 | 0.25 | a pea |
| Venus | 12106 | 0.61 | a dime |
| Earth | 12,756 | 0.64 | a dime |
| Mars | 6,794 | 0.34 | a little fatter than a AA battery |
| Jupiter | 142,800 | 7.19 | |
| Saturn | 120,660 | 6.07 | cereal bowl |
| Uranus | 51,810 | 2.16 | fat end of a baseball bat |
| Neptune | 49,528 | 2.49 | a doorknob |
| Pluto | 2,290 | 0.12 | thickness of a 3.5" floppy disk |
| Quaoar | 1,250 | 0.06 | grain of salt |
| Planet | Mean Orbit Radus |
Scaled Orbit Radius | ||
|---|---|---|---|---|
| kilometers | feet | miles | location | |
| Sun | Washington Square Park (7 St) |
|||
| Mercury | 57,950,000 | 243 | 0.05 | Washington Mews |
| Venus | 108,110,000 | 463 | 0.09 | 8th St |
| Earth | 149,570,000 | 627 | 0.12 | 10th St |
| Mars | 227,840,000 | 955 | 0.18 | The New School 11th St |
| Jupiter | 778,300,000 | 3,264 | 0.62 | Union Square (north end) 17th St |
| Saturn | 1,427,000,000 | 5,984 | 1.13 | south of Penn Station 29th St |
| Uranus | 2,870,300,000 | 12,037 | 2.28 | Rockerfeller Center 52nd St |
| Neptune | 4,497,000,000 | 18,859 | 3.57 | Carl Schurz Park 87 St |
| Pluto | 5,913,000,000 | 24,797 | 4.70 | City College 134 St |
| Quaoar | 6,500,000,000 | 27,259 | 5.16 | Washington Heights 186th St |
Along the way I saw a Webpage announcing Quaoar (also spelled Quaowar) that said how long it would take you to walk there so I thought this might be something interesting that I could relate to. I added a column that calculated how many days it would take me to walk to each planet if I walked 8 yours a day at 3 mph (rounded up to 40 km/day for convenience). It was nearly 4,000 years to walk from the sun just to Mercury so that measurement didn't prove very useful. But it might be useful to say how long it would take to walk the scaled radii.
How I Shrunk the Solar System
Later in the day I was checking to see if I needed to update any occultation maps and remembered that Google Earth has a distance feature and wondered if I could use it to get a better handle on things.When I started measuring things out the farther I got from the sun the greater was the error in the placement of the planets. Must have been the error in the "about" 20 blocks to the mile compounding itself. Everything is much closer than we thought. The Universe must truly be collapsing, and much faster than ever imagined.
I wondered about being able to create a map which I could share with others and started placing pushpins on the map at the appropriate distances. That looked nice and I found that the entire solar system could be placed on Fifth Avenue between its beginning at NYU and the top of Central Park. That is a scale I can get my mind around. But I still have a way to go to get a practical handle on the diameter scale.
Improvements on My Solar System
Today I carried the project a step farther. I learned how to use custom icons with Google Earth (but so far only on my local computer) and how to resize the icons so that my map now shows the correct diameter as well as radius relationship. So at this point I have a shareable map that only has standard icons, but they are the right sizes and in the right places.
(This map will be updated with each change that I make to the solar system so may have the custom icons representing the planets by the time you view it.)
After I figure out how to use my custom icons in a way that allows me to share the map with others I plan to go one step further. I want to go to the location of each planet and photograph the neighborhood and something there that is the appropriate size and figure out how to attach those pictures to the map.
Aside from Clear Sky Clock I use several other resources in deciding whether or not to make the trip down to Central Park for observing. CSC is my quick-look/no-thinking-necessary resource but we don't know how often it is correct. So I hope to start grabbing screen shots of the chart to include with each post so we can compare the prediction with the observed conditions.
My next stop is usually the infrared satellite loop image that shows me where there is moisture and where it is going. That gives me an idea of what has happened cloud-wise in the past several hours and lets me make a guess about whether conditions are likely to get better or worse.
Probably my favorite weather information source is one of the NOAA experimental graphical weather displays. They have several graphical formats they are playing with. The easiest one to find is the one that has the cure pictures of the sun shining from behind the clouds and raindrops falling. But somehow I found the forecast display at NOAA NYC 480-hour Forecast. (I would normally give you the URL here but it is much too long to fit in this column.)
There are four graphs going across the page that show the forecast conditions over a 48-hour period. By using the drop-down list over the chart you can specify the start of the forecast period to any hour during the next six days.
The top chart shows a line graph of the temperature and dewpoint. When conditions warrant they add in either the heat index or the wind chill values. They list the value for every third data point and also denote the time and temperature for the daily high and low.
On the next graph is the wind speed and a flag indicating direction. If they are predicting significant gusts there is a line of data points indicating them.
Graph three is my favorite. It predicts cloud cover and usually shows 10-20% clouds when we are out thinking we have good skies. I suspect that this is based on the brightness of the IR satellite image and includes moisture we don’t see. Also on this graph is relative humidity and precipitation probability. If it is likely that it might rain (or snow) there are probably enough clouds out that I am not even thinking about observing so don’t bother looking at this line unless I am after some rare or high profile event when I am going to take a chance that there will be a gap in the clouds exactly where I need it. I infer from the relative humidity and cloud cover how transparent the air is likely to be.
The bar graph at the bottom is another one that is mostly useless for me since it deals with the type of precipitation expected and how confident they are that it will actually ocur. Even when it has been raining steadily for days I don't recall this graph ever reading above "occasionally".
The gray bar at the bottom of the chart has a summary of the numeric values for the next hour.
posted by Charlie at 22:24
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