# Maximum # of Caches

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Note All numbers are approximate. and calculations rounded.

The surface area of the Earth is approx. 510 million square km. If each Geocache has to be separated by 161 metres it takes up 0.082 square km (in a circle). That means the total number of Geocahces possible is 6,219, 512,195.

Now if 70% of the Earth is water (and we take that part out) that leaves 153,000,000 square km of land for a total possible number of caches of 1, 865, 853, 659 caches (on land).

Now caches can be placed in space, GC1BE91 comes to mind. How about other planets or celestial bodies? That would significantly increase the possibilities. Are there longitude and latitude systems set up for places like the Moon or Mars?

I'm curious!

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That is SO cool! I didn't know there was one on the ISS!

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This is another interesting one. The deepest

Rainbow Hydrothermal Vents

GCG822

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OK....here is another perspective...

Are you more likely to:

1) Eat at every McDonalds

or

2) Find every cache

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OK....here is another perspective...

Are you more likely to:

1) Eat at every McDonalds

or

2) Find every cache

There are 33,000 McDonald's. If you ate 3 meals a day for just over 30 years, you'd have eaten at them all.

There are 1,740,710 active caches according to GC.com. To find all the caches out there in the same 30 year time frame, you'd need to find 159 caches a day for that same 30 years.

Consistently finding 159 caches in a day might be impossible, but so is your heart surviving 30 years of "McFood".

##### Link to comment
OK....here is another perspective...

Are you more likely to:

1) Eat at every McDonalds

or

2) Find every cache

There are 33,000 McDonald's. If you ate 3 meals a day for just over 30 years, you'd have eaten at them all.

There are 1,740,710 active caches according to GC.com. To find all the caches out there in the same 30 year time frame, you'd need to find 159 caches a day for that same 30 years.

Consistently finding 159 caches in a day might be impossible, but so is your heart surviving 30 years of "McFood".

Think of all the swag that would come with that :laughing:

##### Link to comment
OK....here is another perspective...

Are you more likely to:

1) Eat at every McDonalds

or

2) Find every cache

There are 33,000 McDonald's. If you ate 3 meals a day for just over 30 years, you'd have eaten at them all.

There are 1,740,710 active caches according to GC.com. To find all the caches out there in the same 30 year time frame, you'd need to find 159 caches a day for that same 30 years.

Consistently finding 159 caches in a day might be impossible, but so is your heart surviving 30 years of "McFood".

Think of all the swag that would come with that :laughing:

With eating 3 meals at McDonalds every day for 30 years?

##### Link to comment
The surface area of the Earth is approx. 510 million square km. If each Geocache has to be separated by 161 metres it takes up 0.082 square km (in a circle). That means the total number of Geocahces possible is 6,219, 512,195.

Remember that the geocaches exclude a circle, so that the closest packing would be hexagonal. There will always be wasted space. As a result, the maximum number is more like 5.6 billion instead of 6.2 billion.

##### Link to comment
The surface area of the Earth is approx. 510 million square km. If each Geocache has to be separated by 161 metres it takes up 0.082 square km (in a circle). That means the total number of Geocahces possible is 6,219, 512,195.

Remember that the geocaches exclude a circle, so that the closest packing would be hexagonal. There will always be wasted space. As a result, the maximum number is more like 5.6 billion instead of 6.2 billion.

exactly! .... see here

##### Link to comment
The surface area of the Earth is approx. 510 million square km. If each Geocache has to be separated by 161 metres it takes up 0.082 square km (in a circle). That means the total number of Geocahces possible is 6,219, 512,195.

Remember that the geocaches exclude a circle, so that the closest packing would be hexagonal. There will always be wasted space. As a result, the maximum number is more like 5.6 billion instead of 6.2 billion.

But you - and the estimated surface area quoted in the OP - assume a uniform flat surface....

There are also no limits on the number of subterranean caches we could place.

With this in mind, I would put the total figure significantly higher than 6.2 billion, rather than lower

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Now caches can be placed in space, GC1BE91 comes to mind. How about other planets or celestial bodies? That would significantly increase the possibilities. Are there longitude and latitude systems set up for places like the Moon or Mars?

I'm curious!

Yes, they do have lat/long overlays. Problem is.... there is no GPS system in place, other than for the one focusing all of its' attention upon planet Earth.

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Now this is just.... interesting. Wouldn't it be cool if we could send a Nano over there with the next exploration mission?

Being so small and lightweight I bet NASA would at least consider it. Just an idea.

19 August 2004

On Earth, the longitude of the Royal Observatory in Greenwich, England, is defined as the 'prime meridian,' or zero degrees longitude. Locations on Earth are measured in degrees east or west from this position, but where is the equivalent position on Mars?

Earth's prime meridian was defined by international agreement in 1884 as the position of the large 'transit circle', a telescope in the Royal Observatory's Meridian Building. The transit circle was built by Sir George Biddell Airy, the 7th Astronomer Royal, in 1850.

For Mars, the prime meridian was first defined by the German astronomers W. Beer and J. H. Mädler in 1830-32. They used a small circular feature on the surface, which they called 'A’, as a reference point to determine the rotation period of the planet.

The Italian astronomer G. Schiaparelli used this feature as the zero point of longitude in his 1877 map of Mars. It was subsequently named Sinus Meridiani ('Middle Bay') by French astronomer Camille Flammarion.

A crater in the Sinus Meridiani was later called Airy, named to commemorate the builder of the Greenwich transit. When the US Mariner 9 spacecraft mapped the planet at about 1 kilometre resolution in 1972, a more precise definition was needed.

Merton Davies of the RAND Corporation was analysing surface features and designated a 0.5-kilometre-wide crater, subsequently named 'Airy-0' (within the larger crater Airy) as the zero point.

This crater was imaged once by Mariner 9 and once by the Viking 1 orbiter in 1978, and these two images were the basis of the Martian longitude system for the rest of the 20th century.

The US Mars Global Surveyor (MGS) attempted to take a picture of Airy-0 on every close overflight it made since the beginning of its mapping mission. This shows how difficult it is to hit such a small target: nine attempts were required, and the spacecraft did not pass directly over Airy-0 until almost the end of the MGS primary mission in January 2001.

Originally, a system with ‘planetographic’ latitude and longitude increasing to the west was developed to be used with the Viking observations. The US Geological Survey and other organisations then adopted a system with ‘planetocentric’ latitude and longitude increasing to the east for making future Mars maps and imagery. Both systems were approved for use on Mars by the International Astronomical Union in 2000.

(The ‘planetocentric’ system uses co-ordinates derived from the angle measured from the equator to a point on the surface at the centre of the planet, whereas the ‘planetographic’ system uses co-ordinates which are mapped on the surface.)

Most maps produced before 2002 use the earlier co-ordinates system, but now the majority of Mars missions and instrument teams have now adopted the latter system defined for Mars, namely the planetocentric latitude and east longitude system. These definitions have been widely adopted by NASA and ESA missions and other users of planetary data and are likely to remain in use for a decade or more.

The articles featuring the latest Mars images published on the ESA Mars Express web site quote positions given in this latest system, with longitude ranging from 0-360 degrees East. This is different to Earth, where we give longitudes as 0-180 degrees, East or West.

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And lets not forget the Moon.

Selenographic coordinates are used to refer to locations on the surface of Earth's moon. Any position on the lunar surface can be referenced by specifying two numerical values, which are comparable to the latitude and longitude of Earth. The longitude gives the position east or west of the Moon's prime meridian, which is the line of longitude passing through the point on the lunar surface directly facing Earth. (See also Earth's prime meridian.) This can be thought of as the mid-point of the visible Moon as seen from the Earth. The latitude gives the position north or south of the lunar equator. Both of these coordinates are given in terms of degrees.

Astronomers defined the fundamental location in the selenographic coordinate system by the small, bowl-shaped satellite crater 'Mösting A'. The coordinates of this crater are defined as:

Latitude: 3° 12' 43.2" South

Longitude: 5° 12' 39.6" West

The coordinate system has become precisely defined due to the Lunar Laser Ranging Experiment.

Anything past 90°E or 90°W would not be seen from Earth, except for libration, which makes 59% of the Moon visible.

Selenographic colongitude

The selenographic colongitude is the longitude of the morning terminator on the Moon, as measured in degrees westward from the prime meridian. The morning terminator forms a half-circle across the Moon where the Sun is just starting to rise. As the Moon continues in its orbit, this line advances in longitude. The value of the selenographic colongitude increases from 0° to 359° in the direction of the advancing terminator.

Sunrise occurs at the prime meridian when the Lunar phase reaches First Quarter, after one fourth of a lunar day. At this location the selenographic colongitude at sunrise is defined as 0°. Thus, by the time of the Full Moon the colongitude increases to 90°; at Last Quarter it is 180°, and at the New Moon the colongitude reaches 270°. Note that the Moon is nearly invisible from the Earth at New Moon phase except during a solar eclipse.

The low angle of incidence of arriving sunlight tends to pick out features by the sharp shadows they cast, thus the area near the terminator is usually the most favorable for viewing or photographing lunar features through a telescope. The observer will need to know the location of the terminator to plan observations of selected features. The selenographic colongitude is useful for this purpose.

The selenographic longitude of the evening terminator is equal to the colongitude plus 180°.

Longitude

Longitude on the Moon is measured both east and west from its prime meridian. When no direction is specified, east is positive and west is negative.

Roughly speaking, the Moon's prime meridian lies near the center of the Moon's disc as seen from Earth. For precise applications, many coordinate systems have been defined for the Moon, each with a slightly different prime meridian. The IAU recommends the "mean Earth/polar axis" system,[1] in which the prime meridian is the average direction (from the Moon's center) of the Earth's center.

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Until someone sets some GPS satellites in orbit around the moon or another planet the best you'll be able to do is Letterboxing. After all Geocaching minus the GPSr is (almost) Letterboxing.

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I have heard of a few Geocaches on this site that can be found without a GPSr- mainly in Cuba, where one cannot own/possess a GPSr without prior government permission (even the tourists) . From another thread in the forums:

We did a one week vacation at a Varadero area resort in February, 2009. A pocket Query netted five caches available within the peninsula. We found four of them without taking a GPSr with us (the fifth was apparently muggled earlier last year). These caches were well described, and included nearby photos that assisted us to find GZ in every case. We were very pleased at having added 4 caches from Cuba to our geocaching adventures. . So! is there 'Geocaching in Cuba?' - certainly - but without the need of a GPSr.

I think a set of coordinates and a few good hints could have someone on their way- though no doubt they may need some other skills to get it done, Orienteering comes to mind.

Now you know where I would like to see a cache placed? North Korea, what are the chances of that happening. Wonder if there are any in the DMZ?

##### Link to comment
OK....here is another perspective...

Are you more likely to:

1) Eat at every McDonalds

or

2) Find every cache

There are 33,000 McDonald's. If you ate 3 meals a day for just over 30 years, you'd have eaten at them all.

There are 1,740,710 active caches according to GC.com. To find all the caches out there in the same 30 year time frame, you'd need to find 159 caches a day for that same 30 years.

Consistently finding 159 caches in a day might be impossible, but so is your heart surviving 30 years of "McFood".

Dont forget all the new McDonald's popping up in the next 30 years.

##### Link to comment
The surface area of the Earth is approx. 510 million square km. If each Geocache has to be separated by 161 metres it takes up 0.082 square km (in a circle). That means the total number of Geocahces possible is 6,219, 512,195.

Remember that the geocaches exclude a circle, so that the closest packing would be hexagonal. There will always be wasted space. As a result, the maximum number is more like 5.6 billion instead of 6.2 billion.

But you - and the estimated surface area quoted in the OP - assume a uniform flat surface....

Nope. I did not. You will find that the difference between a flat surface and the ellipsoid Earth is not significant in this calculation. The estimate of the size of the effect is not difficult. Let me know if you need help.

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Anything past 90°E or 90°W would not be seen from Earth, except for libration, which makes 59% of the Moon visible.

There is also a (relatively small) effect from parallax. At moonrise and moonset you can see slightly past the 90 degrees longitude because the Earth is larger than the Moon.

##### Link to comment
The surface area of the Earth is approx. 510 million square km. If each Geocache has to be separated by 161 metres it takes up 0.082 square km (in a circle). That means the total number of Geocahces possible is 6,219, 512,195.

Remember that the geocaches exclude a circle, so that the closest packing would be hexagonal. There will always be wasted space. As a result, the maximum number is more like 5.6 billion instead of 6.2 billion.

But you - and the estimated surface area quoted in the OP - assume a uniform flat surface....

There are also no limits on the number of subterranean caches we could place.

With this in mind, I would put the total figure significantly higher than 6.2 billion, rather than lower

But gps coordinates don't take into effect altitude, caches must still be 161 yards away from each other even if there is a 2 mile vertical cliff separating them.

As far as geocaching is concerned the world is perfectly smooth with only more or less terrain stars littering the surface.

At least that is how I understand it

Edited by Vonnegut1982
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Space ... the Final Frontier ... for Geocaching

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For those hoping to geocache on Mars, looks like you're in luck.

http://www.msnbc.msn.com/id/5387135/ns/technology_and_science-space/t/gps-system-mars

But "geo" implies Earth, doesn't it? So shouldn't it be selenocaching and areocaching?

For domain name squatters, quick, selenocaching.com is not registered yet. Selenocaching - Yet Another Pile of Rocks Hide.

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Space ... the Final Frontier ... for Geocaching

<snipped image>

With all that wide open, available space, this is more likely what would happen:

The TRUE E.T. Highway!

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