Observing space curvature.

[xelasnave]

I have been thinking about Eddington's observation of space curvature as predicted by GR.
Could we make such observations using a disk to replicate the Moon.
Using filters whatever we set the mount running and measure to test GR.
I just think it would be a great project. OK why wont it work?

[Somnium]

you mean a coronagraph? if i am understanding you correctly, you want to simulate a solar eclipse with a coronagraph and image a background star's position to test GR? you would still need a generally dark sky, an eclipse make the whole atmosphere dark, you would still be imaging through light and unlikely to see any stars ...

[xelasnave]

I think we need an eclipse.

[xelasnave]

Well here is the chalenge.
Can we photograph stars in day time near the Sun.
Seems impossible but is it.
Could you somehow use a filter and a light frame style subtract to remove atmospheric dust... any idea is worthy to do the seemingly impossible.

[xelasnave]

Maybe really dark glass... Must be a way.

[Somnium]

i have thought about this a bit. the stars are still providing the same flux during the day, the only issue is that the background noise has become a serious issue and completely drowns out any signal from the star. surely if the sun is blocked out and you take a stack of images of the surrounding sky, you may just be able to tease out the signal in the noise with stacking

[xelasnave]

I take that as highly encouraging.
I set up to capture a Earth eclipse of the Moon.
Had shutter speeds set close to what I needed.
Took some shots the Moon was faint as, so extended the shutter speed again and again.
I think it went to a minute.
Later I found only half the shutter was openning.
Thats where all the light went.
However the Moon photos were excellent with stars in the back ground so maybe a dark filter for the Sun.
I have unrealistic visions of a decent wide field shot with the Sun cruising through.
I think we have to do it from space really.

[xelasnave]

Mayby the radio scope guys are doing this already

[Somnium]

i am sure they are, we also have the soho scope which can do it

[xelasnave]

Thanks

[xelasnave]

a few of their ideas maybe.
if you were high in a desert maybe you could get stars but not near the Sun.

[pmrid]

What about the old " down the mine " trick. Never tried it but it may serve to limit the background flux. Finding a hole deep enough and pointing in the right direction could be problematic.
peter🌞🌙✨

[bojan]

This "trick" will not remove the bacground noise we are talking about here.

[KenGee]

Alex if you want a direct measurement of space curvature, why not measure the position of Mercury?

[Eratosthenes]

I would have thought that it would be a lot more difficult to observe a perfectly FLAT region of space.

Even a Neutrino, with its tiny tiny mass, technically imparts a curvature in space (time)

:D

[xelasnave]

Yes that would work. Thanks Ken.

[xelasnave]

It would be tiny tiny about one third a pofteenth I recon.
The Sun does no bend it much and the Moon much much less so.
Sorry I cant be specific but its out there somewhere if you want the amount.

[Eratosthenes]

isn't micro-lensing an form of space bending that can be observed?

[xelasnave]

I dont know what can you tell me about it?

[Somnium]

good point, one project i am looking to do down the track is to try and image gravitational lensing in galaxy clusters. fascinating stuff. micro lensing might be difficult to observe for an amateur ... my understanding on the topic is that generally these are one off detection events so it is difficult to monitor known stars with micro lensing. also i am sure the signal would be really difficult to tease out of the noise, especially in the conditions that most amateurs are in and the gear that we have ...

[Eratosthenes]

It was predicted by Einstein's General Relativity theory.

https://en.wikipedia.org/wiki/Gravitational_microlensing

I am fairly certain that this effect has been observed and it is due to the direct curvature of space caused by a massive object (gravitational field)

Do you accept that light being distorted or bent around a massive object that has curved space is conclusive evidence of "space" being curved?

[xelasnave]

Yes it was.
Thanks I could have looked up wiki.. I thought you were leading up to something.
You asked.
As to evidence of curvature I dont know other than Eddington followed by other observations (two historic observations in Australia) use those observations in support of GR.
I initially was interested in doing an observation replicating one of those observations.
Without an eclipse, capturing stars near the sun in daylight... Impossible stuff I just want to know how to do it.. But my attention has gone to other things

[Eratosthenes]

.....have scientists just discovered gravitational waves???

https://www.rt.com/news/328632-ripples-waves-gravitational-einstein/

[xelasnave]

If they have maybe they will do a paper.

[perrin6]

Sometimes I think I'm going round the bend, now I wonder if it's just me being in tune with curved space.

[Eratosthenes]

the source of the rumor on gravitational waves was Lawrence Krauss

(.....astrophysicists get involved with all sorts of issues Alex.

Yes, Odysseus was real


Astrophysicists have identified the date the suitors of Penelope were killed
http://neoskosmos.com/news/en/Yes-Odysseus-was-real (http://neoskosmos.com/news/en/Yes-Odysseus-was-real)

"Odysseus arrived in Ithaca on 25 October, 1207BC. Five days later there was an eclipse with 75 per cent coverage in the Ionian sea, and it is precisely when the massacre of Penelope's suitors took place," says Papadima. She is entirely convinced of the truthfulness of the described event.
The occurrence of the solar eclipse at that time has been proven with maps by NASA, describing foreseeable natural phenomena from 4500BC to AD10,000.
"Between 1300BC and 1130BC, the years during which the two epics take place, there were 14 solar eclipses. Of the five that would have been visible in the Ionian, two of them had a rate of two per cent helium and therefore were not noticed. Another was west of the sun, so our concern is only with two," explains Papadima.
A total solar eclipse took place in 1143BC, close to the decline of the Mycenaean centres and therefore excluded by the scientists. The second took place on 30 October, 1207BC, in the afternoon until 5.30 pm, reflected in The Odyssey."

[Rob_K]

That's a pretty weird article Peter, thanks for posting. Hope it's not a career-ender for the "multi-disciplinary team"! :)



Ah yes those damned 2% helium eclipses are exceedingly difficult to see. :confused2: New one on me, back to the schoolbooks? :lol: And as for those other eclipses that are west of the Sun, well, no chance. :rolleyes: I hope they mean the disc of the Moon passed to the west of the Sun, ie not an eclipse at all, at least from Ithaca. :shrug:



Eclipses must have been a lot more powerful in ancient times. Nowadays 3/4 coverage and you can't tell the difference from a normal sunny day. ;)

Cheers -

[xelasnave]

I wonder how early in mans history humans could predict an eclipse.

[xelasnave]

I speculate that civilisation started with one man who came to power because he said he would put out the Sun and did so... Probably many stories like that.. If there isnt I will write a book.

[Eratosthenes]

the earliest eclipse predicting device is the "Antikythera Mechanism" which is described as the first mechanical computer - Ancient Greece around 200 BC (calculations predicting eclipses even predate the Antikythera Mechanism)

This device could predict eclipses, model planetary motion (5 planets known at the time) etc.

An astonishing mechanism for that time that used gears and levers and was about the size of a shoe box. It could also predict the direction and color of the shadow as the eclipse occurred.
http://www.antikythera-mechanism.gr/system/files/images/IMG00268.preview.jpg

https://giahorary.files.wordpress.com/2011/11/antikythera-model-frontal.jpg

[Eratosthenes]

...we tend to underestimate the technology and resourcefulness of ancient civilisations.

The ancient Greeks invented the world's first mechanical computer (Antikythera mechanism) that could predict eclipses and planetary motion etc.

The Babylonian civilisation had documented all sorts of astronomical events and periodic behaviour in the skies including cycles that extended to as much as 19 years.

Eclipses and other astronomical events were often attributed to supernatural and religious causes (although not by all, as there were many ancient philosophers that believed in a natural cause in every event and observation seen in the environment)

[bojan]

Have a look at this web page:
http://eclipse.gsfc.nasa.gov/SEsaros/SEsaros.html

and here:
https://en.wikipedia.org/wiki/Saros_%28astronomy%29

[xelasnave]

Thanks Bojan

[rustigsmed]

The Sun has been obliterated from the sky, and an unlucky darkness invades the world

Is an eclipse described in the Odyssey?
http://www.pnas.org/content/105/26/8823.full

[Eratosthenes]

I will see your Homer and raise you an Irish archaeoastronomer, Paul Griffin at November 30, 3340 BC

http://www.astronomy.ca/3340eclipse/

[rustigsmed]

interesting, I wonder what his interpretation of the famous triple swirls are?