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Do "starshades" make sense?



 
 
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  #1  
Old January 13th 19, 02:30 AM posted to sci.astro.amateur
RichA[_6_]
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Default Do "starshades" make sense?

It's mentioned in this speculative space telescope video. The idea is to create an eclipse using a large, calculated shade which would allow a star to be occluded and planets around it to be seen. I get occluding the star, but how would a much, much dimmer planet be seen at all, even by a large telescope?

https://www.youtube.com/watch?v=BIASPc89Sgk

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  #2  
Old January 13th 19, 04:46 AM posted to sci.astro.amateur
Chris L Peterson
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Default Do "starshades" make sense?

On Sat, 12 Jan 2019 17:30:56 -0800 (PST), RichA
wrote:

It's mentioned in this speculative space telescope video. The idea is to create an eclipse using a large, calculated shade which would allow a star to be occluded and planets around it to be seen. I get occluding the star, but how would a much, much dimmer planet be seen at all, even by a large telescope?

https://www.youtube.com/watch?v=BIASPc89Sgk


Enough light is reflected from a great many planets to be detected
with a telescope this size. As long as the central star can be
occluded.
  #3  
Old January 13th 19, 08:15 AM posted to sci.astro.amateur
Gerald Kelleher
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Default Do "starshades" make sense?

https://www.youtube.com/watch?v=3VVCiPp67vI

https://www.youtube.com/watch?v=pZFalMW_dq0

Start with the planets nearest our parent star.

  #4  
Old January 13th 19, 02:40 PM posted to sci.astro.amateur
Gerald Kelleher
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Posts: 1,528
Default Do "starshades" make sense?

On Sunday, January 13, 2019 at 1:30:58 AM UTC, RichA wrote:
It's mentioned in this speculative space telescope video. The idea is to create an eclipse using a large, calculated shade which would allow a star to be occluded and planets around it to be seen. I get occluding the star, but how would a much, much dimmer planet be seen at all, even by a large telescope?

https://www.youtube.com/watch?v=BIASPc89Sgk


Cracks me up that the programme by these youngsters is prefaced with 'Earth Rotation' in the intro where the Earth is supposed to turn once in 24 hours to the Sun (it doesn't) and 23 hours 56 minutes 04 seconds to the stars (it doesn't).

The Sun is in view from sunrise to sunset and the stars are in view from sunset to sunrise any day or rotation within a year. It represents a single 24 hour day/ 360 degree rotation cycle apart from the Polar day/night cycle which arises from a separate rotation as a function of orbital motion.

What is happening at the moment is that the old relativists are dying off and being replaced by celestial sphere youngsters who have only known the RA/Dec framework whereas the theorists may as well be moonies such is their voodoo so adrift of observations.

Behind it all is a small but growing voice which invites people to return to more exciting possibilities opened up by imaging including the time lapse provided by the SOHO satellite with its own sun visor.

A more natural one is the distance between observer and horizon at dawn and twilight so long as the observer knows they are looking close to the centre of the solar system where the residual light is and Sirius is seen just below the meteor in that spectacular image -

https://apod.nasa.gov/apod/ap181123.html









  #5  
Old January 14th 19, 12:36 AM posted to sci.astro.amateur
Quadibloc
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Default Do "starshades" make sense?

On Saturday, January 12, 2019 at 6:30:58 PM UTC-7, RichA wrote:
I get occluding the star, but how would a much, much dimmer planet be seen at
all, even by a large telescope?


Of course, the fact that the telescope is *in space* means that occluding the star
can work just about perfectly. So, since occluding can work just about perfectly,
if the star is fairly nearby, a planet might not be dimmer than, say, one of the
galaxies in the Hubble Deep Field photograph.

John Savard
  #6  
Old January 14th 19, 01:15 AM posted to sci.astro.amateur
RichA[_6_]
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Default Do "starshades" make sense?

On Sunday, 13 January 2019 18:36:05 UTC-5, Quadibloc wrote:
On Saturday, January 12, 2019 at 6:30:58 PM UTC-7, RichA wrote:
I get occluding the star, but how would a much, much dimmer planet be seen at
all, even by a large telescope?


Of course, the fact that the telescope is *in space* means that occluding the star
can work just about perfectly. So, since occluding can work just about perfectly,
if the star is fairly nearby, a planet might not be dimmer than, say, one of the
galaxies in the Hubble Deep Field photograph.

John Savard


Mars would be about 2.4E-11 dimmer to us, at the distance of Alpha Centauri I think.
  #7  
Old January 14th 19, 06:11 AM posted to sci.astro.amateur
Chris L Peterson
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Default Do "starshades" make sense?

On Sun, 13 Jan 2019 16:15:54 -0800 (PST), RichA
wrote:

On Sunday, 13 January 2019 18:36:05 UTC-5, Quadibloc wrote:
On Saturday, January 12, 2019 at 6:30:58 PM UTC-7, RichA wrote:
I get occluding the star, but how would a much, much dimmer planet be seen at
all, even by a large telescope?


Of course, the fact that the telescope is *in space* means that occluding the star
can work just about perfectly. So, since occluding can work just about perfectly,
if the star is fairly nearby, a planet might not be dimmer than, say, one of the
galaxies in the Hubble Deep Field photograph.

John Savard


Mars would be about 2.4E-11 dimmer to us, at the distance of Alpha Centauri I think.


Which would mean around mag 28, which is several times brighter than
the dimmest star Hubble can detect. But the proposed planet hunting
telescope has a larger mirror than the HST. So detecting a Mars-like
planet at over a parsec sounds completely feasible.
  #8  
Old January 14th 19, 01:46 PM posted to sci.astro.amateur
Gerald Kelleher
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Posts: 1,528
Default Do "starshades" make sense?

People here are so endearing considering how difficult they find planet hunting the faster moving Venus and Mercury as they run in front and then behind our central Sun -

https://www.youtube.com/watch?v=3VVCiPp67vI&t=20s

All they have to do is match the motions in the real timelapse with models of the same planetary motions -

https://www.youtube.com/watch?v=pZFalMW_dq0

The real bonus is proving the Earth's orbital motion by subtracting stellar circumpolar motion and realising the background stars move from left to right of the Sun.

Another endearing trait is that elsewhere I can explain the partitioning of direct/retrograde motions between faster and slower moving planets with the Earth's orbital motion providing the differing perspectives to great approval. Once I mention that the partitioning comes from me then it all becomes nasty while I basically shrug at the lack of attribution.

You people have a sun visor every day, it is called the distance between observer and horizon at dawn and twilight.

  #9  
Old January 15th 19, 05:45 AM posted to sci.astro.amateur
RichA[_6_]
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Posts: 1,055
Default Do "starshades" make sense?

On Monday, 14 January 2019 00:11:54 UTC-5, Chris L Peterson wrote:
On Sun, 13 Jan 2019 16:15:54 -0800 (PST), RichA
wrote:

On Sunday, 13 January 2019 18:36:05 UTC-5, Quadibloc wrote:
On Saturday, January 12, 2019 at 6:30:58 PM UTC-7, RichA wrote:
I get occluding the star, but how would a much, much dimmer planet be seen at
all, even by a large telescope?

Of course, the fact that the telescope is *in space* means that occluding the star
can work just about perfectly. So, since occluding can work just about perfectly,
if the star is fairly nearby, a planet might not be dimmer than, say, one of the
galaxies in the Hubble Deep Field photograph.

John Savard


Mars would be about 2.4E-11 dimmer to us, at the distance of Alpha Centauri I think.


Which would mean around mag 28, which is several times brighter than
the dimmest star Hubble can detect. But the proposed planet hunting
telescope has a larger mirror than the HST. So detecting a Mars-like
planet at over a parsec sounds completely feasible.


They want to combine the starshield with that other plan for the diffractive telescope using a 100 meter diffraction disk. 100-1000 times the resolution of the Hubble.
  #10  
Old January 15th 19, 08:49 AM posted to sci.astro.amateur
Gerald Kelleher
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Posts: 1,528
Default Do "starshades" make sense?

On Tuesday, January 15, 2019 at 4:45:20 AM UTC, RichA wrote:
On Monday, 14 January 2019 00:11:54 UTC-5, Chris L Peterson wrote:
On Sun, 13 Jan 2019 16:15:54 -0800 (PST), RichA
wrote:

On Sunday, 13 January 2019 18:36:05 UTC-5, Quadibloc wrote:
On Saturday, January 12, 2019 at 6:30:58 PM UTC-7, RichA wrote:
I get occluding the star, but how would a much, much dimmer planet be seen at
all, even by a large telescope?

Of course, the fact that the telescope is *in space* means that occluding the star
can work just about perfectly. So, since occluding can work just about perfectly,
if the star is fairly nearby, a planet might not be dimmer than, say, one of the
galaxies in the Hubble Deep Field photograph.

John Savard

Mars would be about 2.4E-11 dimmer to us, at the distance of Alpha Centauri I think.


Which would mean around mag 28, which is several times brighter than
the dimmest star Hubble can detect. But the proposed planet hunting
telescope has a larger mirror than the HST. So detecting a Mars-like
planet at over a parsec sounds completely feasible.


They want to combine the starshield with that other plan for the diffractive telescope using a 100 meter diffraction disk. 100-1000 times the resolution of the Hubble.


I must activate the starshield in my car this evening but I really know it is just a sun visor that helps diminish glare for safe driving.

I like it here because contributors seem completely immune to anything in front of them while outside the newsgroup those who become partially familiar with productive perspectives are inclined to screw things up. In this respect Copernicus didn't fear Church censure he just was wary of the many drones which circle less productive convictions but are distracted long enough to make a balls of new ones.

The idea is fine, however, when the hapless refuse to accept the principles for the planets nearest to our own star and to our slower moving planet then people make a mockery of themselves given the SOHO imaging which effectively shields out the glare of the Sun.

The planet Mars is seen to move forward against the moving stellar background with the Sun at the centre around February 1996 so it would be another year before Mars started to process a direct/retrograde loop in February 1997 -

https://www.youtube.com/watch?v=pZFalMW_dq0&t=29s

This supports actual timelapse of the same observation -

https://www.youtube.com/watch?v=3VVCiPp67vI&t=60s

The Venus comes careering into view in June 1996 as it passes in front of the Sun and so it goes for those who could but won't interpret what is happening in our home planet.











 




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