DM51
Flashaholic
The Japan earthquake has reportedly moved the whole country ~2 meters from where it was before. I also saw a report somewhere that it had affected the earth's rotation very slightly; the figure I saw quoted was that there had been a time change of 1 microsecond.
I don't know if either of these figures is accurate; quite possibly not. But they raise an interesting point, which maybe an expert on the GPS system could answer.
The essence of GPS is to keep extremely accurate time, as light/radio waves travel very fast (186,000 miles per second). In 1 microsecond, light will travel approx 1/5 mile, or ~1,000 feet. How will they reset the GPS system to correct for this change? Will it be automatic, or does someone in the US Defense Dept. or somewhere have to reset the timing on the GPS satellites? Has anyone noticed inaccuracies in their GPS since the earthquake?
I have Google Maps on my cellphone, and I was interested to see it was about 20 feet off when I checked it yesterday.
I don't know if either of these figures is accurate; quite possibly not. But they raise an interesting point, which maybe an expert on the GPS system could answer.
The essence of GPS is to keep extremely accurate time, as light/radio waves travel very fast (186,000 miles per second). In 1 microsecond, light will travel approx 1/5 mile, or ~1,000 feet. How will they reset the GPS system to correct for this change? Will it be automatic, or does someone in the US Defense Dept. or somewhere have to reset the timing on the GPS satellites? Has anyone noticed inaccuracies in their GPS since the earthquake?
I have Google Maps on my cellphone, and I was interested to see it was about 20 feet off when I checked it yesterday.