Re: Bright Explosion on the Moon

[Hactar]

In article <ve0lp8t1mdsequdal...@4ax.com>,
M C Hamster <davo...@nospam-speakeasy.net> wrote:
> On Thu, 16 May 2013 23:22:47 -0700, BillTurlock wrote:
>
> >
> >Bright Explosion on the Moon
> >NASA Science News for May 17, 2013
> >
> >NASA researchers who monitor the Moon for meteoroid impacts have
> >detected an explosion ten times brighter than anything they've seen
> >before.
> >
> >FULL STORY:
> >http://science.nasa.gov/science-news/science-at-nasa/2013/16may_lunarimpact/
> >
> >VIDEO: http://www.youtube.com/watch?v=IYloGuUZCFM
>
> The meteoroid is estimated to have been travelling at 56,000 miles per
> hour when it collided with the moon. The earth-moon system itself is
> travelling about 66,000 miles per hour in its orbit around the sun.
> This made me wonder what other zippy objects are flying around the
> universe. Here's a nice article on the subject:
> http://www.cosmosmagazine.com/features/extreme-speed/
>
> A few numbers: Mercury travels at a speed of over 105,000 MPH.
> Astronomers have identified a planet in a distant solar system which
> is traveling at 528,000 mph. The solar system is traveling at a
> speed of 568,000 MPH around the center of the Milky Way galaxy.
>
> The article also cites a distant star estimated to be travelling at a
> speed of 1.55 million miles per hour, but now we're just getting
> silly.
>
> What seems odd to me is how to think about velocity for some of these
> objects... against what frame of reference?

Why, the ether of course. For solar system objects, I think you can
reason out the orbital velocity given the radius and masses involved.
Those are reasonably frame-independent.

--
-eben QebWe...@vTerYizUonI.nOetP royalty.mine.nu:81
LIBRA: A big promotion is just around the corner for someone
much more talented than you. Laughter is the very best medicine,
remember that when your appendix bursts next week. -- Weird Al

[Hactar]

In article <er5lp81e3siant9gi...@4ax.com>,
Les Albert <lalb...@aol.com> wrote:

> On Mon, 20 May 2013 15:21:09 -0500, M C Hamster
> <davo...@nospam-speakeasy.net> wrote:
>
>
> >The meteoroid is estimated to have been travelling at 56,000 miles per
> >hour when it collided with the moon. The earth-moon system itself is
> >travelling about 66,000 miles per hour in its orbit around the sun.
> >This made me wonder what other zippy objects are flying around the
> >universe. Here's a nice article on the subject:
> >http://www.cosmosmagazine.com/features/extreme-speed/
> >A few numbers: Mercury travels at a speed of over 105,000 MPH.
> >Astronomers have identified a planet in a distant solar system which
> >is traveling at 528,000 mph. The solar system is traveling at a
> >speed of 568,000 MPH around the center of the Milky Way galaxy.
> >The article also cites a distant star estimated to be travelling at a
> >speed of 1.55 million miles per hour, but now we're just getting
> >silly.
> >What seems odd to me is how to think about velocity for some of these
> >objects... against what frame of reference?
>

> Star velocity measurement is by Doppler effect ... red shift, blue
> shift.

So then, relative to the earth (unless the measurememtn were made from
elewhere). Hopefully it's averaged appropriately to cancel out Earth's
orbital and rotational velocities.