also it was 28 years ago.
Harry
On Fri, Feb 15, 2013 at 5:09 PM, Alexander Hollins
<alexander.holl...@gmail.com> wrote:
> ignore me, i just realized the error in my mental model.
>
> On Fri, Feb 15, 2013 at 3:08 PM, Alexander Hollins
> <alexander.holl...@gmail.com> wrote:
>>
>> The Moon makes about 13 revolutions in the course of a year.
>>
>> revolutions around what?
>>
>> On Fri, Feb 15, 2013 at 3:05 PM, Harry Veeder <hveeder...@gmail.com>
>> wrote:
>>>
>>> On Fri, Feb 15, 2013 at 3:50 PM, Alan Fletcher <a...@well.com> wrote:
>>> > At 12:14 PM 2/15/2013, you wrote:
>>> >
>>> > On Fri, Feb 15, 2013 at 2:22 PM, James Bowery <jabow...@gmail.com>
>>> > wrote:
>>> >> Obvious question:
>>> >> Was the vector correlated with that of the earth approaching asteroid?
>>> >
>>> > No, they were almost perpendicular. Pure and delightful coincidence.
>>> >
>>> >
>>> > That was my first thought.
>>> >
>>> > <
>>> >
>>> > http://www.washingtonpost.com/world/europe/meteorite-injures-more-than-900-in-
>>> >
>>> > russian-city/2013/02/15/ff67c624-7770-11e2-aa12-e6cf1d31106b_story.html?wprss=r
>>> > ss_europe>
>>> >
>>> > Sergei Zakharov, regional branch chairman of the Russian Geographic
>>> > Society, told the Interfax news agency that three explosions occurred
>>> > as the meteor blew apart.
>>> >
>>> > “Judging by my observations, the fireball was flying from southeast to
>>> > northwest,” he said. “A bright flare of more than 2,500 degrees
>>> > [Celsius] happened before the three explosions. The first explosion was
>>> > the strongest.”
>>> >
>>> > - - - - -
>>> >
>>> > My quick take (partly copied from elsewhere)
>>> >
>>> > Consider a small object (in this case the meteor) orbiting a large
>>> > object (asteroid), as seen from above the orbit.
>>> >
>>> > If the orbital velocity of the meteor round the asteroid is small,
>>> > then the trajectory of the meteor will look like a sine wave around the
>>> > trajectory of the asteroid.
>>> >
>>> > (Similarly, the trajectory of the moon looks like a sine wave
>>> > superimposed on the orbit of the earth).
>>>
>>> I thought so too 25 years ago, when my instructor in an introductory
>>> course on astronomy asked
>>> us what we thought the trajectory of the moon is around the sun. It is
>>> actually a curve which is always convex...
>>>
>>> http://www.math.nus.edu.sg/aslaksen/teaching/convex.html
>>>
>>> <<It is not a circle, but is close to a 12-gon with rounded corners.
>>> It is locally convex in the sense that it has no loops and the
>>> curvature never changes sign.>>
>>>
>>> harry
>>>
>>
>
