Astronomers Fix the Astronomical Unit

gbrumfiel writes "The Astronomical Unit (AU) is known to most as the distance between the Earth and the Sun. In fact, the official definition was a much more complex mathematical calculation involving angular measurements, hypothetical bodies, and the Sun's mass. That old definition created problems: due to general relativity, the length of the AU changed depending on an observer's position in the solar system. And the mass of the Sun changes over time, so the AU was changing as well. At the International Astronomical Union's latest meeting, astronomers unanimously voted on a new simplified definition: exactly 149,597,870,700 meters. Nobody need panic, the earth's distance from the sun remains just as it was, regardless of whether it's in AUs, meters, or smoots."

Comments

Re:let's not waste significant digits!

[girlintraining]

if politicians can be SD-conservative, why can't astronomers? we all know that significance is precious and rare...

It was decided by committee. I'm sure it was a compromise of several possible values, with concessions on each side, a few attempts to filibuster it until Pluto was given recognition again, etc. No, I'm not trying to be funny.

Re:Distance remains the same?

[mblase]

Since the Earth's orbit around the Sun is eliptical it's _never_ the same, is it?

Even an elliptical orbit is right twice a year.

The new AU ...

[PPH]

... will be established by machining a bar of pure platinum to a length of exactly 1 AU. It will be stored in a vault in Paris.

Re:They should mesure it in miles.

[GodfatherofSoul]

92,955,807.3 miles

Your answer is SOO 8 minutes ago...