In long: That depends. What do you mean by "relative position"? How accurate do you want that to be? What do you mean by "input from the user"? There are systems in use today that could be combined together with software to find a very imprecise location - Know what date and time it is, take a snapshot of the visible sky, correlate from the height and declination of visible stars on the horizon. That would give you a figure probably somewhere on the accuracy of within forty square miles. We used to practice using lookup tables and star charts for Orienteering in Boy Scouts. I don't think anyone's actually implemented such a thing in hardware because A: image processing not terribly advanced until recently and B: GPS satellites.
There's also the possibility of using which craters are visible on the surface of the moon, along with the elevation, and knowing the date and time (the moon currently shows the same features to a given longitude on every orbit - it "rolls" around the earth), but again no extant portable off-the-shelf hardware modules and the moon is technically a satellite.
so, not really, no. And the computational methods for working it out don't work if you don't have a way of keeping and knowing time.
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timeasmymeasure
no subject
Date: 2009-06-18 04:08 pm (UTC)In short, no.
In long: That depends. What do you mean by "relative position"? How accurate do you want that to be?
What do you mean by "input from the user"?
There are systems in use today that could be combined together with software to find a very imprecise location - Know what date and time it is, take a snapshot of the visible sky, correlate from the height and declination of visible stars on the horizon. That would give you a figure probably somewhere on the accuracy of within forty square miles. We used to practice using lookup tables and star charts for Orienteering in Boy Scouts. I don't think anyone's actually implemented such a thing in hardware because A: image processing not terribly advanced until recently and B: GPS satellites.
There's also the possibility of using which craters are visible on the surface of the moon, along with the elevation, and knowing the date and time (the moon currently shows the same features to a given longitude on every orbit - it "rolls" around the earth), but again no extant portable off-the-shelf hardware modules and the moon is technically a satellite.
so, not really, no. And the computational methods for working it out don't work if you don't have a way of keeping and knowing time.