Any Astronomy Buffs Here?

[DevilHorse]

I didn't have the CC on, but I stayed on until the Solar Panels unfurled (nice). Apparently that will be the last human view of the JWST.

Larry
DevilHorse

It looks like everyone is getting a new telescope for Christmas.

Latest info is that a mid-course correction occurred successfully around 10pm last night. The JWST is about 160km out now (~7:30am Sunday). All's well.

Larry
DevilHorse

[camion]

I didn't have the CC on, but I stayed on until the Solar Panels unfurled (nice). Apparently that will be the last human view of the JWST.

Larry
DevilHorse

Isn't it nice to have a Christmas present that unwraps itself so neatly?


I'm looking forward to this gift sending back presents for future Christmases.

[BLPOG]

I don't know about you but I don't spend all of my time wondering about the James Webb Space Telescope (JWST). But there are a few salient features of the JWST and the mission that have been mentioned, that are quite obvious, but would seem to be in contradiction. Whether you are curious or not, or just don't recognize that there are puzzle pieces that are not fitting together, that's OK, because we trust that these major problems have been worked out by the many great scientists working on the project. But there are a few obvious ones that have occurred to me over recent weeks that I finally decided to ask and have gotten the answer to:

OK, if the JWST is at the L2 Lagrange point, it suggests that it is in the direction of the Earth's shadow relative to the sun all the time (like the moon is during a total lunar eclipse). That means that either the earth is blocking the sun (good for any telescope to see the stars) or the sun looks like an annular eclipse (not quite as good for telescope, but explains a lot of JWST features) to the JWST. Features on the JWST suggesting it is the latter include: communications is sort of line of sight (we DO expect to communicate with the JWST!), the JWST has solar panels for power (what is the source of solar energy if the JWST can't see the sun?), why are those 5 big sun shield elements built on there if the JWST isn't exposed to the sun?

This article answers those questions and more:
https://www.quora.com/How-can-JWST-r...hadow-of-Earth

Larry
DevilHorse

I haven't read the quora page, but for those who want the short-form answer: JWST will orbit L2

[JStuart]

Saturday morning should be the last chance to catch Comet Leonard as a morning comet. On December 12th, the comet gives its closest approach, and switches to being an evening comet. I just got a new flash that Leonard is now visible to the naked eye, so it is certainly visible with binoculars. Weather has been limiting for me, so no chance. Certainly, the tail will get a little larger as it approaches the sun, but it isn't getting much closer.

Good luck.

Larry
DevilHorse

So, with very clear skies last night, and a reasonable horizon view, I searched once again for Leonard, and found with binoculars a bright object where it 'should' have been. Not visible without binocs. With my Celestron SCT, I scanned the area, and could only find a bright object with no real definition, and if it really were Comet Leonard, It had no distinguishing features. I'll claim I saw it, but I really can't prove it. Did it ever get as bright as it was forecast to be?
Any of you guys had any luck seeing it at all?
Happy New Year,
JStuart

[DevilHorse]

So, with very clear skies last night, and a reasonable horizon view, I searched once again for Leonard, and found with binoculars a bright object where it 'should' have been. Not visible without binocs. With my Celestron SCT, I scanned the area, and could only find a bright object with no real definition, and if it really were Comet Leonard, It had no distinguishing features. I'll claim I saw it, but I really can't prove it. Did it ever get as bright as it was forecast to be?
Any of you guys had any luck seeing it at all?
Happy New Year,
JStuart

I had no luck, but a few days ago I saw several very nice pictures of Leonard taken some backyard astronomers. More of a blob, but with a little tale (it was there, but certainly faint for binoculars). I'd say you found it!! Search for "Leonard" on twitter and scroll past vulcans.

Larry
DevilHorse

[DevilHorse]

I haven't read the quora page, but for those who want the short-form answer: JWST will orbit L2

Quite so. As we know, L2 is an unstable Lagrange point. So work is needed by any spacecraft to stay near/in the L2. But these craft only have to be near, not at the exact point (what is a few kM amongst friends?). There is some informative stuff about what JWST will do (Halo orbit) and what kinds of orbits can be done at these links:
https://en.wikipedia.org/wiki/Halo_orbit
https://en.wikipedia.org/wiki/Orbital_station-keeping

Thanks for your comment that led me to further 'exploration'.

Larry
DevilHorse

[CameronBornAndBred]

So, with very clear skies last night, and a reasonable horizon view, I searched once again for Leonard, and found with binoculars a bright object where it 'should' have been. Not visible without binocs. With my Celestron SCT, I scanned the area, and could only find a bright object with no real definition, and if it really were Comet Leonard, It had no distinguishing features. I'll claim I saw it, but I really can't prove it. Did it ever get as bright as it was forecast to be?
Any of you guys had any luck seeing it at all?
Happy New Year,
JStuart

I had no luck, but a few days ago I saw several very nice pictures of Leonard taken some backyard astronomers. More of a blob, but with a little tale (it was there, but certainly faint for binoculars). I'd say you found it!! Search for "Leonard" on twitter and scroll past vulcans.

Larry
DevilHorse

I'm hoping to go look tonight since I'm running out of time and we have clear skies. My problem is that I just hernia repair surgery and I'm limited to what I can lift. My 8" telescope is way more than 10lbs. If I get some help, and If I find it, I'll try to post some lousy photos that I'll be taking through my phone.

[-jk]

I'm hoping to go look tonight since I'm running out of time and we have clear skies. My problem is that I just hernia repair surgery and I'm limited to what I can lift. My 8" telescope is way more than 10lbs. If I get some help, and If I find it, I'll try to post some lousy photos that I'll be taking through my phone.

Ouch! Get well soon!

-jk

[JStuart]

I'm hoping to go look tonight since I'm running out of time and we have clear skies. My problem is that I just hernia repair surgery and I'm limited to what I can lift. My 8" telescope is way more than 10lbs. If I get some help, and If I find it, I'll try to post some lousy photos that I'll be taking through my phone.

Indeed, get well soon. Clouds all over tonight, darn it.

[DevilHorse]

OK, so you want to know exactly what the James Webb Telescope is up to?

How about this Webb-site:
https://jwst.nasa.gov/content/webbLa...ereIsWebb.html

Did you know that the JWST started its' journey at 22,000 MPH and is now slowed to 2360 MPH. (Looks like it is past the moon. But I digress..) And will progressively get slower as it approaches the L2 Lagrange point. At this time the meter says 0.6555 miles/second (multiply by 3600 seconds per Hour to get Miles per Hour - MPH). Fun stuff if you get bored at work or its a commercial break during a bowl game. You can also track progress as the satellite unfurls.

The scale of the timeline is in days (not distance). Go by percentage of distance if you'd like, but the earth's gravity will be slowing the JWST tremendously till it just eeks into the L2.

Larry
DevilHorse

[OldPhiKap]

What other body forms the equilibrium at L2 besides Earth? I (think that I) understand L1 between the Earth and Sun but not really L2 through L5.

Great link, thanks!

[CameronBornAndBred]

Indeed, get well soon. Clouds all over tonight, darn it.

Yep, clouds here too

[sagegrouse]

Indeed, get well soon. Clouds all over tonight, darn it.

Snowing every day here -- and we love it!

[DevilHorse]

What other body forms the equilibrium at L2 besides Earth? I (think that I) understand L1 between the Earth and Sun but not really L2 through L5.

Great link, thanks!

The sun.
lagrange1.jpg
(picture not to scale)

<geek>
Evidently there are quite a few satellites that have visited the L2 Lagrange point of the Earth-Sun system over the past 20 years since 2001 (when it started). Apparently the fuel to keep these satellites in place runs out in about 10 years and then those satellites drift out of L2 and adopt a solar orbit. This is about 4 times the distance from the earth to the moon (900kmiles vs. 235kmiles ~ 0.26 but that's not using significant numbers).

If you want to know how to calculate the L2 Lagrange point, you calculate the gravitational tug of the sun plus the gravitational tug of the earth (use Newton's gravitational formula) [you can add 1.2% to the mass of the earth to account for the moon] on a random mass and balance it out with the centrifugal force of the same random mass revolving around the sun at the radius of the earth +900kmiles, every 365.25 days. The hardest part is making sure you use the right units and precision on the numbers.

L1 is the point where the pull of the sun is equal to the pull of the earth plus Centrifugal force. Centrifugal force matters Also, obviously unstable. You get closer to one body, and that's it; slippery slope.
</geek>

Larry
DevilHorse

[Skydog]

Thanks for the explanations. I must really be avoiding work because I further wikipedia’d my rudimentary understanding of the 5 Lagrange points for mutually orbiting bodies and now understand why Webb is at L2. And this non-astronomer now even knows what a barycentre is!*

*And why the Earth-Moon barycentre is beneath the earth’s surface but the Pluto-Charon barycentre is in space between the two bodies.

PS - And now I can’t wait for my next cocktail party (which I definitely go to all the time) because I’m pretty sure I will be able to clear out my corner of the room in no time!

[wavedukefan70s]

I swear it must be standard practice of the astronomy gods. Bought several lenses filters ect.
For my sons new telescope . It has been either cloudy or foggy every night except 2 .

[DevilHorse]

Thanks for the explanations. I must really be avoiding work because I further wikipedia’d my rudimentary understanding of the 5 Lagrange points for mutually orbiting bodies and now understand why Webb is at L2. And this non-astronomer now even knows what a barycentre is!*

*And why the Earth-Moon barycentre is beneath the earth’s surface but the Pluto-Charon barycentre is in space between the two bodies.

PS - And now I can’t wait for my next cocktail party (which I definitely go to all the time) because I’m pretty sure I will be able to clear out my corner of the room in no time!

Had to go to google to learn the term barycentre. Never showed up in Astronomy/Physics classes. We just called it the Center of Mass.

If you want to do some advanced thinking (break your brain) consider what the Centroid is.
Where would the Centroid of the continental USA be? If I told you Smith Center, you'd never believe me.

Here is a fun fact about things "inside" mass spheres. If you had a hollow (vacuum) sphere of mass. The gravity inside is... zero! Zilch. Assuming you could breath (and see) you could be weightless inside the big hollow sphere.
So, as you go further inside a planet, you are only affected by the mass of the planet remaining below you.


Larry
DevilHorse

[OldPhiKap]

If you want to do some advanced thinking (break your brain) consider what the Centroid is.
Where would the Centroid of the continental USA be? If I told you Smith Center, you'd never believe me.

Larry
DevilHorse

I think you mean “Hemorrhoid of the continental USA.”

[CameronBornAndBred]

I swear it must be standard practice of the astronomy gods. Bought several lenses filters ect.
For my sons new telescope . It has been either cloudy or foggy every night except 2 .

I've got the full Celestron kit, which I'm very happy with, but often times I'm completely lazy and don't want to fuss with replacing lenses while I'm watching something and having to refocus every time I swap them out.
This eyepiece has been the perfect answer.

The Orion E-Series Zoom eyepiece allows you to change magnification power without swapping out eyepieces
A simple twist of the zoom eyepiece housing changes the focal length from 21mm to 7mm, providing a variety of viewing magnification powers

https://www.amazon.com/Orion-E-Serie...34974961&psc=1

Only drawback is that it won't keep away the clouds.

[DevilHorse]

Only drawback is that it won't keep away the clouds.

It doesn't have to be that way:
https://www.firstlightoptics.com/mis...cloud-gun.html

Go Buck Rogers!!

Larry
DevilHorse