Measuring The Distance From Earth To Moon

lewiz writes: "Tom Murphy at UW is attempting to measure the distance between the Earth and The Moon to the nearest millimetre according to this BBC News article. 'His tape measure will be a giant telescope at Apache Point in New Mexico. Retroreflectors left on the surface of the Moon by various space missions, including the Apollo 11 lunar landing, will also come in handy.'"

Comments

Oddly Enough...

[CheshireCatCO]

... according to my Solar Systems Dynamics textbook, we already know the rate at which the Moon is receding from the Earth: 1 nanometer/second. Which is, of course, a better precision than this group seeks to take on. But that measurement probably used the Doppler shift. It just goes to show that it's much easier to measure radial velocities than distances!

Umm, the distance isn't constant

[DeafDumbBlind]

The moon revolves around the earth in an eliptical orbit, not a circular one. Unless he's talking about getting the average distance.

Re:My tax dollars at work...

[pclminion]

The moon's orbit varies by far more than 1 millimeter all the time. There are all sorts of influences, including the earth's gravity, the sun's gravity, Jupiter's gravity -- as well as factors that will introduce error into the measurements, such as refraction of the laser in the earth's atmosphere.

Therefore, by measuring the distance to an accuracy of a millemeter, we might be able to gain some insight about: earth's gravity, the sun's gravity, and Jupiter's gravity. The point of this experiment is not to know how far it is to the moon. The point is to better understand the moon's orbit, and the various influences which affect it.

Another totally worthless experiments

[trenton]

How about this one: build a clock that can be taken to sea. What good is that? We already have accurate clock on the shore. Oh, right, you can figure out your latitude. And, in the process, invent roller bearings and bimetallic strips, two extremely useful technologies, ones we weren't even trying to create. That turned out well for us, huh?

The moon distance measurement is obviously good. It seeks to do something no one else has ever achived. Even if the results aren't interesting, the new techniques used are. Anyone that doesn't see its intrinsic value is shortsighted.

Re:Reflectors on the moon? It's a lie !!!

[laserjet]

I hate to ask... but, has anyone actually seen the video on moonmovie.com? I am wondering if it is any good or not.

another question: don't we have telescopes good enough that we could see things that were "left" on the moon, like the lunar rovers, their boots and gloves, etc.? It would seem that would put the "did we really land on the moon?" controversey to rest....