grumble at wolfe comment made attached to guardianarticle

Gerry Quinn · 09 Feb 2011, 22:52 · from 2011-February.txt.gz

This is the message as the crawl holds it, before anything here touched it. What the conversation shows has been through ingest: transfer encodings decoded, attachments dropped, quote markers repaired, and the archiver’s ? resolved into quotation marks and dashes. Those repairs are judgements and some of them are wrong, which is what this page is for. Email addresses are obscured here as they are everywhere else on the site, so it is before our repairs rather than byte for byte.

From: gerryq at indigo.ie (Gerry Quinn)
Date: Wed, 9 Feb 2011 22:52:29 -0000
Subject: (urth) grumble at wolfe comment made attached to guardianarticle
References: <SNT123-W400DB386713A3D18B7614CCFEA0 at phx.gbl><4D51DA82.6010103 at verizon.net><AANLkTimQ4=4ST=cMrEf_kvvVJP7=ygPS1U=iBpDCBthx at mail.gmail.com><1D98E2C398854830BEB19325EE3A27DE@jill><AANLkTik4G0iA_uaY4w4WigfOjqcrMi0DD1Aeny0Bxf3E at mail.gmail.com><8AC6534E159C45C9B82792E595D233FD@jill>	<4D52272C.3010600 at io.com>	<AANLkTimO+KjhzHaW7iBMUFfXe-uw6Yu12CO2ot0opOOo at mail.gmail.com><1D44D6669EA441B78E6880BA3C756D6F@jill>	<4D52B3BF.8050302 at io.com><ED7B32A5DD134490883A57D774EA45F0@jill>
	<4D5312DA.5040102 at io.com>
Message-ID: <8796D1A4C16E4AEE811726BB8FFEFD56@jill>


From: "Jeff Wilson" <jwilson at io.com>
> On 2/9/2011 9:59 AM, Gerry Quinn wrote:
>> From: "Jeff Wilson" <jwilson at io.com>
>>> On 2/9/2011 6:26 AM, Gerry Quinn wrote:
>>
>>>> I think horseshoes are a bit problematic. If you look at Cruithne's
>>>> orbit, its actual distance from Earth varies on a short scale with a
>>>> period of one year. Over a longer term, the average distance varies.
>>>> Since Cruithne's orbital period is one year, there's no room for
>>>> meaningful six-year conjunctions.
>>>
>>> That's because tiny Cruithne is too small to influence Earth in a
>>> detectable way. Janus and Epimethius, however, are similar in mass and
>>> do their thing in four years.
>>
>> But their orbital period around Saturn is only 0.7 days... so those four
>> years are equivalent to about 2000 years on Blue!
>
> That may depend heavily on odd power functions, like the orbital period 
> formula earlier; the dual orbit discovery was pre-internet (1978) so I'm 
> having a devil of a time locating anything analytical about it.

I think it's going to be a general property of horshoe orbits that the 
period between conjunctions will be very long compared to the orbital 
period.  The reason being that the two objects are essentially in the same 
orbit, albeit going a little faster or slower at times.  So their orbital 
speeds cannot differ much, and can only catch up or fall behind over a 
period of many orbits.

- Gerry Quinn

An unofficial mirror of a public mailing list · about & removal requests · download the archive · before the list · original archive at urth.net