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31-03-2020, 06:08 PM
1

Ponderings

Why are German Shepherd dogs not used for tending sheep?

Why are sheep dogs called Collies?

Why is it that stars twinkle but planets do not?

Why is there sometimes a green flash across the sky just before dawn?

Not that isolation is effecting me at all!!
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31-03-2020, 06:15 PM
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Re: Ponderings

Originally Posted by Silver Tabby ->
Why is it that stars twinkle but planets do not?
Good question - here's the answer:

https://skyandtelescope.org/astronom...stars-twinkle/

WHY DO STARS TWINKLE?

Though it wouldn’t work so well in the nursery rhyme, a there is actually a technical term for when stars twinkle: astronomical scintillation, an effect due to our planet’s atmosphere. As light travels through the blanket of air around our planet, it is diffracted (bounced around) causing a quick apparent dimming and brightening — a star's signature "twinkle".

While some stars do physically change in brightness over time, they typically do so on long timescales — amateur astronomers monitor these changes sometimes over hours, but more often over days, weeks, or years. These variable stars are well studied and often signal complex physical changes happening to the stars in question.

The more rapid changes of scintillation, on the other hand, come about long after the light has left the star. Light waves traveling through Earth’s atmosphere diffract as they pass through pockets of air at different temperatures. Because the light waves come from a single point, this effect can make the star’s brightness and/or position appear to change.

WHY DON'T PLANETS TWINKLE TOO?

Unlike stars, planets don't twinkle. Stars are so distant that they appear as pinpoints of light in the night sky, even when viewed through a telescope. Because all the light is coming from a single point, its path is highly susceptible to atmospheric interference (i.e. their light is easily diffracted).

The much closer planets appear instead as tiny disks in the sky (a distinction more easily discerned with a telescope than with the naked eye). Their apparent sizes are usually larger than the pockets of air that would distort their light, so the diffractions cancel out and the effects of astronomical scintillation are negligible.
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31-03-2020, 06:15 PM
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Re: Ponderings

I think German shepherds were used to protect flocks rather than herd them, hence the shepherd monica.

Stars twinkle because they are suns and emit light, whereas planets only reflect the light emitted by the stars, hence the much less intensity.

Can't help you with the rest, and the above two are probably wrong as well, but replying passed a couple of minutes on so well worth the effort....
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31-03-2020, 06:17 PM
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Re: Ponderings

Originally Posted by Omah ->
Good question - here's the answer:

https://skyandtelescope.org/astronom...stars-twinkle/



Crikey Omah, google spoils all the fun...
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31-03-2020, 06:27 PM
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Re: Ponderings

Originally Posted by Barry ->
Crikey Omah, google spoils all the fun...
What's your pondering, then .....
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31-03-2020, 06:30 PM
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Re: Ponderings

Originally Posted by Omah ->
Good question - here's the answer:

https://skyandtelescope.org/astronom...stars-twinkle/



Wow! Thank you, Omah!
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31-03-2020, 06:32 PM
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Re: Ponderings

Originally Posted by Barry ->
I think German shepherds were used to protect flocks rather than herd them, hence the shepherd monica.

Stars twinkle because they are suns and emit light, whereas planets only reflect the light emitted by the stars, hence the much less intensity.

Can't help you with the rest, and the above two are probably wrong as well, but replying passed a couple of minutes on so well worth the effort....
Thank you, Barry. Isn't it amazing what 'Isolation' dredges up in the brain box??!!
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31-03-2020, 06:34 PM
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Re: Ponderings

Originally Posted by Silver Tabby ->
Wow! Thank you, Omah!
So, why do stars with planets wobble .....
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31-03-2020, 06:50 PM
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Re: Ponderings

Originally Posted by Omah ->
So, why do stars with planets wobble .....
As a guess I would say because of the gravity influences of the planets, but why not google it?
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31-03-2020, 06:56 PM
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Re: Ponderings

Has anyone noticed that if you look directly at a distant star, you can't see it whereas if you look just to one side, you can?
 
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