[Lex Computer & Tech Group/LCTG] where is Webb
Tony
galaitsis at verizon.net
Wed Dec 29 06:54:13 PST 2021
Upon further reflection of _/*all*/_ factors affecting L2, the following
points should also be considered, and my "piece of cake" comment in my
earlier note should be ignored (invalid):
1) The Earth's Umbra extends about 0.87-million miles. At the
0.93-million mi distance of L2, the Web Telescope (Web) will never be
totally in the dark Umbra. So, as Larry pointed out, the Web will always
see a sliver of the sun. However, the size of the sliver will vary due
to the following.
2) Most of the citations in the web refer to L2 as a "point". It is a
point in the cosmic sense but a rather "large region" because of the
following reasons:
* The Earth's orbit around the sun is elliptical, not circular.
Therefore, the L2-location fluctuates annually along the "radial"
direction (Sun-Earth line)
* The L2 location is defined in the context of a 3-body system
(Sun-Earth-Web). However, the moon (4th body) causes L2 to fluctuate
monthly both "radially" and "perpendicularly" with respect to the
Sun-Earth line
* Thus, the "perturbed L2" (at gravitational equilibrium with respect
to Sun-Earth-Moon) will move annually within an ovoid volume around
the ideal 3-body L2
* Therefore, the Web Telescope will experience a variable exposure to
Solar radiation annually
Tony
================
On 12/28/21 8:42 PM, Tony wrote:
>
> Supplement to address Carl's question:
>
> Remember that the earth totally eclipses the moon (when suitably
> aligned), which is about 1/4 million miles away and has a ~2000-mi
> diameter (3,468 KM). So, at 1 million miles distance (4 times the
> Earth-Moon distance) the earth could eclipse an object that has a 500
> miles diameter. SO, the telescope will truly be a piece of cake in
> that shadow.
>
> Tony
>
> =======
>
> On 12/28/21 6:16 PM, George Gamota wrote:
>>
>> The location of the Webb is such that only some square feet need to
>> be blocking the sun. Some geometry here helps.
>>
>> *From:* Carl Lazarus <carllazarus at comcast.net>
>> *Sent:* Tuesday, December 28, 2021 5:14 PM
>> *To:* 'George Gamota' <ggamota at stma-llc.com>; 'Stephen Quatrano'
>> <stefanoq at gmail.com>; jjrudy1 at comcast.net
>> *Cc:* 'Lex Computer Group' <lctg at lists.toku.us>
>> *Subject:* RE: [Lex Computer & Tech Group/LCTG] where is Webb
>>
>> Is Earth’s shadow large enough to completely block the sun from the
>> James Webb telescope? I thought the telescope has an elaborate sun
>> shield.
>>
>> -- Carl
>>
>> *From:* LCTG <lctg-bounces+carllazarus=comcast.net at lists.toku.us> *On
>> Behalf Of *George Gamota
>> *Sent:* Tuesday, December 28, 2021 3:41 PM
>> *To:* 'Stephen Quatrano' <stefanoq at gmail.com>; jjrudy1 at comcast.net
>> *Cc:* 'Lex Computer Group' <lctg at lists.toku.us>
>> *Subject:* Re: [Lex Computer & Tech Group/LCTG] where is Webb
>>
>> Basically the Webb would be fried (electronics burned) if it ever
>> sees the sun. So L2 places it in such a way that the Earth blocks the
>> sun (an eclipse) all the time. Thus the Webb goes around the sun with
>> Earth. Webb’s orbit then is one year just as the Earth.
>>
>> George.
>>
>> *From:* LCTG <lctg-bounces+ggamota=stma-llc.com at lists.toku.us> *On
>> Behalf Of *Stephen Quatrano
>> *Sent:* Tuesday, December 28, 2021 1:08 PM
>> *To:* jjrudy1 at comcast.net
>> *Cc:* Lex Computer Group <lctg at lists.toku.us>
>> *Subject:* Re: [Lex Computer & Tech Group/LCTG] where is Webb
>>
>> Great graphics, John. I didn’t understand L2 orbit so I Googled it:
>>
>> "The space telescope is destined to orbit a point in space known as
>> Earth-sun Lagrange point 2 or L2, which is located nearly 1 million
>> miles (1.5 million kilometers) away from Earth on the opposite side
>> as the sun. The spacecraft covered the first 10% of that journey
>> within 12 hours of launching.”
>> https://www.space.com/james-webb-space-telescope-trajectory-burn
>>
>> "The James Webb Space Telescope will not orbit the Earth like Hubble
>> but will in fact orbit the Sun. It will travel for approximately 30
>> days before reaching what is known as the second Lagrange point, or
>> L2, 1 million miles away.”
>> https://deepfieldfilm.com/discover/james-webbs-halo-orbit
>>
>> Looking at the second animation, I’m still not sure I understand it…
>> but I keep trying.
>>
>> Regards,
>>
>> Stephen Quatrano
>> CEO and Cofounder | Meema, Inc
>> web: http://meemastories.com
>> email: stephen.quatrano at meemastories.com
>> <mailto:stephen.quatrano at meemastories.com>
>> cell: +1 781-266-8799
>> https://www.linkedin.com/in/quatrano/
>>
>> Board Member | The Right Question Institute
>> http://www.rightquestion.org
>>
>> Lifelong Learner
>> http://www.howdoweknow.info/p/home.html
>> http://stefano.quatrano.us/
>>
>> On Dec 28, 2021, at 12:35 PM, <jjrudy1 at comcast.net>
>> <jjrudy1 at comcast.net> wrote:
>>
>> This is a nice NASA site that shows its location in
>> realtimehttps://www.jwst.nasa.gov/content/webbLaunch/whereIsWebb.html
>> <https://www.jwst.nasa.gov/content/webbLaunch/whereIsWebb.html>
>>
>> John Rudy
>>
>> 781-861-0402
>>
>> 781-718-8334 cell
>>
>> 13 Hawthorne Lane
>>
>> Bedford MA
>>
>> jjrudy1 at comcast.net <mailto:jjrudy1 at comcast.net>
>>
>> <image001.png>
>>
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