Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Seany on 05/04/2008 12:22:32
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Why do they twinkle??
*twinkle twinkle little star...*
Is it because the hydrogen burning or something?? But surely its really too far away for us to see it flash?? Its like light years away!!
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They twinkle cos all the star fairies that live on each star are waving at you !....this is true...
Oh.....and it may have something to do with the earths atmosphere that the light travels through bends and twists it slightly to give it the appearance of twinkling........which is why...telescopes in space have such a big advantage......there's no atmosphere to corrupt the light path albeit, there still may be spacey stuff in the way....but, intrinsically, the earths atmosphere plays havoc !!
....however, my leaning is towards the star fairies.....!!
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oops...sorry..seany...I accidentally modified your post but in fact changed nothing !!
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Very good explanation but you forgot, to add, also because they are smiling..... :)
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They twinkle cos all the star fairies that live on each star are waving at you !....this is true...
Oh.....and it may have something to do with the earths atmosphere that the light travels through bends and twists it slightly to give it the appearance of twinkling........which is why...telescopes in space have such a big advantage......there's no atmosphere to corrupt the light path albeit, there still may be spacey stuff in the way....but, intrinsically, the earths atmosphere plays havoc !!
....however, my leaning is towards the star fairies.....!!
Thanks Neil.. So is the light like diffracted from the atmosphere of the earth, and kinda wavers or something to get the twinkle effect??\
Of of course.. The waving! [;D]
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oops...sorry..seany...I accidentally modified your post but in fact changed nothing !!
It is OK... But there is this red pipet thing on the folder!
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oops...sorry..seany...I accidentally modified your post but in fact changed nothing !!
It is OK... But there is this red pipet thing on the folder!
Hmm.. But I think that makes this thread always at the top?? I think you made a mistake Neily.. But I'm happy with that [:P]
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They twinkle cos all the star fairies that live on each star are waving at you !....this is true...
Oh.....and it may have something to do with the earths atmosphere that the light travels through bends and twists it slightly to give it the appearance of twinkling........which is why...telescopes in space have such a big advantage......there's no atmosphere to corrupt the light path albeit, there still may be spacey stuff in the way....but, intrinsically, the earths atmosphere plays havoc !!
....however, my leaning is towards the star fairies.....!!
Thanks Neil.. So is the light like diffracted from the atmosphere of the earth, and kinda wavers or something to get the twinkle effect??\
Of of course.. The waving! [;D]
Yep....it's diffracted alright !
Cos of all the flowing atmosphere !
Hmmm...seems your thread has stickied itself !!....I'll unstick it chum !!
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They twinkle cos all the star fairies that live on each star are waving at you !....this is true...
Oh.....and it may have something to do with the earths atmosphere that the light travels through bends and twists it slightly to give it the appearance of twinkling........which is why...telescopes in space have such a big advantage......there's no atmosphere to corrupt the light path albeit, there still may be spacey stuff in the way....but, intrinsically, the earths atmosphere plays havoc !!
....however, my leaning is towards the star fairies.....!!
Thanks Neil.. So is the light like diffracted from the atmosphere of the earth, and kinda wavers or something to get the twinkle effect??\
Of of course.. The waving! [;D]
Yep....it's diffracted alright !
Cos of all the flowing atmosphere !
Hmmm...seems your thread has stickied itself !!....I'll unstick it chum !!
But if there is a constant diffraction, why would it twinkle? Wouldn't it just adjust the positioning of the star?
LOL Neil,... You didn't NEED to unsticky it.. LOL! [:P]
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They twinkle cos all the star fairies that live on each star are waving at you !....this is true...
Oh.....and it may have something to do with the earths atmosphere that the light travels through bends and twists it slightly to give it the appearance of twinkling........which is why...telescopes in space have such a big advantage......there's no atmosphere to corrupt the light path albeit, there still may be spacey stuff in the way....but, intrinsically, the earths atmosphere plays havoc !!
....however, my leaning is towards the star fairies.....!!
Thanks Neil.. So is the light like diffracted from the atmosphere of the earth, and kinda wavers or something to get the twinkle effect??\
Of of course.. The waving! [;D]
Yep....it's diffracted alright !
Cos of all the flowing atmosphere !
Hmmm...seems your thread has stickied itself !!....I'll unstick it chum !!
But if there is a constant diffraction, why would it twinkle? Wouldn't it just adjust the positioning of the star?
LOL Neil,... You didn't NEED to unsticky it.. LOL! [:P]
I unstuck it chum cos it stickied itself all by itself !!
erhmm ok...as far as the twinkling is concerned .....everybody here knows that I am a bona fide cosmologist right up there on Soul Surfers league**..
but...to keep things simpler I felt it easier to blatantly copy and paste this from here
http://www.enchantedlearning.com/subjects/astronomy/stars/twinkle.shtml
The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere.
Stars (except for the Sun) appear as tiny dots in the sky; as their light travels through the many layers of the Earth's atmosphere, the light of the star is bent (refracted) many times and in random directions (light is bent when it hits a change in density - like a pocket of cold air or hot air). This random refraction results in the star winking out (it looks as though the star moves a bit, and our eye interprets this as twinkling).
Stars closer to the horizon appear to twinkle more than stars that are overhead - this is because the light of stars near the horizon has to travel through more air than the light of stars overhead and so is subject to more refraction. Also, planets do not usually twinkle, because they are so close to us; they appear big enough that the twinkling is not noticeable (except when the air is extremely turbulent).
Stars would not appear to twinkle if we viewed them from outer space (or from a planet/moon that didn't have an atmosphere).
** A total and complete lie that you already knew !!
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*le Phew*...shhhhhh.....*sheepy whispers*
I hope that got me out of the increasingly klevur questions I was being asked about stars...!!
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I unstuck it chum cos it stickied itself all by itself !!
erhmm ok...as far as the twinkling is concerned .....everybody here knows that I am a bona fide cosmologist right up there on Soul Surfers league**..
but...to keep things simpler I felt it easier to blatantly copy and paste this from here
http://www.enchantedlearning.com/subjects/astronomy/stars/twinkle.shtml
The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars twinkle when we see them from the Earth's surface because we are viewing them through thick layers of turbulent (moving) air in the Earth's atmosphere.
Stars (except for the Sun) appear as tiny dots in the sky; as their light travels through the many layers of the Earth's atmosphere, the light of the star is bent (refracted) many times and in random directions (light is bent when it hits a change in density - like a pocket of cold air or hot air). This random refraction results in the star winking out (it looks as though the star moves a bit, and our eye interprets this as twinkling).
Stars closer to the horizon appear to twinkle more than stars that are overhead - this is because the light of stars near the horizon has to travel through more air than the light of stars overhead and so is subject to more refraction. Also, planets do not usually twinkle, because they are so close to us; they appear big enough that the twinkling is not noticeable (except when the air is extremely turbulent).
Stars would not appear to twinkle if we viewed them from outer space (or from a planet/moon that didn't have an atmosphere).
** A total and complete lie that you already knew !!
Thank ewe very much Neil! [;D]
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No one seems to have mentioned that it's an interference / diffraction effect. The fact is that, there are multiple paths through the atmosphere and, because of varying refractive index, some take longer than others. The result is that you are constantly getting constructive and distructive interference between the arriving waves as conditions change. This causes the light from 'one particular direction' to come and go (twinkle). When you see light from a star, the light is only from one very narrow range of angles and the twinkling effect is visible. Your eye (or even a telescope) will be too narrow to resolve the angle subtended by any visible star (diffraction limit) so you will just see one source which varies in intensity.
Once the object you are looking at has a finite angular size - planet/ satellite etc, your eye gets light from many different points on the object. The larger range of directions means that the light you see is a combination of cancellations and additions. This smooths out the 'twinkles' so you see Mars, for instance as a very tiny, steady disc. A small enough satellite, illuminated brightly enough would probably twinkle but I don't know if this has been tried.
You can certainly see twinkling of small bright lights at ground level if they are far enough away to look like points, too.