theastrophysicist

Go read the article, and you’ll see that said scientist claims that the day should have shortened by 1.26microsecond, and that such a change would be difficult to detect. Here, we investigate why the change IS difficult to detect, given that we are able to send satellites into space and have an immensely powerful GPS system.

A change of 1 microsecond corresponds to a 1.16e-11 fractional change in the length of a day. This means that in 1 day, the earth would rotate 1.16e-11*2π faster. Thus, from the point of view of a GPS system, after 1 day, points on earth’s equator would be 1.16e-11*2π*Radius of Earth=0.5mm away from their expected position. Points away from the equator would have a smaller change in position, since they are closer to the axis of rotation, so we don’t really bother with those points.

Thus, our result shows that the predicted change is indeed difficult to measure over this short timescale. However, if 10 years (3653 days) down the road, we would get an absolute error of 1.7m in GPS readings near the equator, which is probably detectable with current GPS technologies.

However, within this period, I would expect other events to change the period of the earth’s rotation, so the scientist’s claim that it is difficult to detect is indeed understandable.

Let’s face it though: having 1 microsecond less sleep a day isn’t that big of a deal anyway.

henrysztul:

Holy Moley! This article, seen via gizmodo, says that the Chilean earthquake shifted the earths axis by 3” which shortens our days by 1.26us (microseconds).

Oh, also the island of Santa Maria was raised 2 meters after the quake, no big deal.  Shnickies!