What is the moon slowly receding from us and by how much each year?

Moon's receding orbit and angular momentum

• I am having trouble understanding the physics of a question that has been asked before here. Your answer in 2005, like similar explantions elsewhere, made perfect sense until I checked the basic equations. The Moon-Earth orbit currently is increasing in radius while decreasing both the Earth's rotation rate and the Moon's rotation rate, which is synchronous to the orbit. I understand how the lagging tides on Earth, pushed ahead of the Moon by the Earth's rotation, would add momentum to the Moon while taking it from the Earth's spin. This should give the Moon a slight kick to raise its orbit (make it a bit elliptical, actually, but tidal forces on the Moon then would tend to circularize its orbit.) My problem is that I can't see how momentum is conserved. The rotation rate of any circular orbit, W, is proportional to the inverse of the radius, R, to the power of 3/2. (This I found by equating the force of gravitation to the centripetal force.) Angular momentum of an orbiting body is the rotation rate, w, times the radius, R, times the mass, m*w*R, and therefore is proportional to the inverse of the square root of R. So as the Moon in a higher orbit should have less momentum. Now one possibility, perhaps, is that an elliptical orbit has more momentum and that the Moon's is becoming more elliptical. Actually, hmmm. Is this what's going on? Or am I wrong on something?

• Answer:

  John..John!!.. You had to ask me this now! :) I am dead busy in project work. What i ll do is lead you to this site. refer:- http://www.scienceagainstevolution.org/v5i5d.htmTo answer myself, i would have to redo everything from scratch and give you an answer, which might have earned me a doctorate!! :) too bad I am not upto re-inventing wheels at this time. Please excuse me this time, I admit I dont have all the maths at the tip of my fingers. (If I had, I would be as well flash gordon or Zharkov)! enjoy that page, and most probably "hey presto" you will realise where you may have gone wrong! Dont worry, the recession rate observed by laser ranging instruments today matches the slowing down of the earth observed by the cesium atomic clocks of the national time keeping agency of the USA. sorry once again, regards Jayen Johnny! I made your week, showed you the most relevent site, and i get a 6 on the knowledge ratings...all because i did not have time! come on how ironic can this world get? to cap it all, we experts HAVE to persevere. It is heart breaking if not back breaking work. Ofcourse i have seen worse days..with people giving niggardly 1s as though like hottentots their world could never go beyond 3! by that standard you have been generous indeed. the search strings have to be contextually correct and you always get quick results. If i remember right, i used the string "lunar recession conservation of angular momentum". regards Jayen