Flickering stars

[Fas-ligand]

Anyone ever notice a star flickering blue red and white before? I just saw a good example tonight. Anyone know the why it flickers?

[Acy]

I think I've read somewhere that stars twinkle due to pollution in the atmosphere.

Stars aren't supposed to flicker like that.

[Fas-ligand]

Originally posted by Acy
I think I've read somewhere that stars twinkle due to pollution in the atmosphere.

Stars aren't supposed to flicker like that.

I was wondering if it was that or possibly space debris...

[coleslaw]

Well, technically, it's not really pollution that makes the stars flicker. It's actually just the atmosphere. Atmospheric shifting or twinkling causes the different color components of the incoming light to get refracted by different amounts, which causes the star to sometimes change color rapidly. It's as though the atmosphere was a prism and your eye is only getting a glimpse of one color at a time.

[Fas-ligand]

Originally posted by coleslaw
Well, technically, it's not really pollution that makes the stars flicker. It's actually just the atmosphere. Atmospheric shifting or twinkling causes the different color components of the incoming light to get refracted by different amounts, which causes the star to sometimes change color rapidly. It's as though the atmosphere was a prism and your eye is only getting a glimpse of one color at a time.

Sounds like a good explaination to me. So the atmosphere is filtering certain wavelenghts at random and that's why we see colors?

[ProMinx]

Resident Astrophysics student stepping forward here. Stars seem to twinkle because they're passing through the atmosphere, as coleslaw said, but the twinkling is actually a result of variable temperature in the atmosphere. The heat running through the upper atmosphere causes shimmering, much like the illusory puddles you notice over the road on a hot day.

ProMinx

[verve247]

Interesting. So how exactly does changing the temp. of the atmosphere produce a visible color cange in the stars. Are molecules in the atmosphere affected by the heat (i.e. strain on the chemical bonds) or is there a change of composition in the atmosphere?

[ArkiStan]

I don't know about the flickering, but I've always been told that a surprisingly large percentage of the "stars" we see in the sky are actually satellites.

[ArkiStan]

Originally posted by verve247
Interesting. So how exactly does changing the temp. of the atmosphere produce a visible color cange in the stars. Are molecules in the atmosphere affected by the heat (i.e. strain on the chemical bonds) or is there a change of composition in the atmosphere?

I can't answer your question, but I bet it's the same reason that when you take a night flight over a city, all the lights you see flicker in a very similar manner.

[zenbooty]

Originally posted by ProMinx
Stars seem to twinkle because they're passing through the atmosphereHoly ****! We're gonna fry!!! :heh:

[Cantacuzene]

Its weird too that stars twinkle but planets don't.

[Fas-ligand]

Originally posted by DarkFury

If the Earth gave off light like the Sun... wouldn't the surface be "molten and violent" like the Sun's? :shrug:

(Just a theory based on limited knowledge... :hihi: )

I think the light coming from the Earth is due to some kind of reflection, probably with particles in the atmosphere. There are extremely cold planets in our solar system that we can see as light in the sky.

[ProMinx]

Alright, I guess that I need to clarify my explanation a bit. The star twinkle because their light is travelling through OUR atmosphere. Sorry for the confusion. Also, the light we see from other planets is a reflection. Every planet has a reflection co-efficient referred to as the Geometric Albedo. Something with an Albedo of 0 is a perfect blackbody (reflects no light and only emits radiation based on temperature) while an Albedo of 1 corresponds to an item that reflects 100% of every type of radiation. Here is a list of the Albedos for some well-known objects in our Solar System:

Mercury 0.106
Venus 0.65
Earth 0.367
Moon 0.12
Mars 0.150
Jupiter 0.52
Europa (moon of Jupiter) 0.64
Saturn 0.47
Enceladus (moon of Saturn) 1.0
Phoebe (moon of Saturn) 0.5/0.05 (depending on which side face the earth)
Uranus 0.51
Neptune 0.41
Pluto 0.3

Any other astro questions? I'll help to the best of my ability :P

ProMinx

[revil]

Originally posted by ProMinx
Any other astro questions? I'll help to the best of my ability
Next you'll be saying the moon isn't made of cheese! Your a crazy man! CRAZY MAN! BURN HIM! BURN HIM! HE'S A WITCH! A WITCH!

ok, a real question... you know any online site that gives lots of useful information pertaining to your field of study, yet not dumbed down to the common man?

[mojo]

Originally posted by ProMinx
Alright<snip> Here is a list of the Albedos for some well-known objects in our Solar System:
<snip>

Earth 0.367anyone curious as to what this could mean...when we see the "dark side" of the moon, but yet it's slightly grayish and not completely black, that's called "earth shine"...or what prominx described above. so the earth reflects the sun, and then we get yet another reflection of that from the moon.

another note from above is that the atmospheric conditions described above are known by astronomers as atmospheric seeing. the variety of things that occur in the atmosphere (clouds, heat differences, etc) all contribute to the superiority of the hubble telescope :P

i'm not quite sure where we're going with this yet tho :hmm:

[WhiskeyPapa]

Originally posted by revil
Next you'll be saying the moon isn't made of cheese! Your a crazy man! CRAZY MAN! BURN HIM! BURN HIM! HE'S A WITCH! A WITCH!
I thought we had already proven on this site (http://www.gotapex.com/forums/showthread.php?threadid=53841) that the "moon" is a liberal lie.

[Grimm]

Originally posted by Fas-ligand


Sounds like a good explaination to me. So the atmosphere is filtering certain wavelenghts at random and that's why we see colors? While it does filter, the reason you see the different colors is that the light is being refracted. The changes in atmosphere cause the refraction to constantly change, causing the "twinkeling".

Think of it as a light source across the room from you. there is a prism of some sort directly between your eyes and the light source. This prism is being randomly moved, so the refracted light that reaches your eyes constantly changes. It appears as if the light source changes colors. The prism represents the atmosphere.

[mojo]

well also consider that there's the doppler shift. so both colors are always present but not seen by the naked eye.

stars rotate like, really fast. the side that's rotating toward you will present a blue hue (shorter wavelength) and that which goes away presents a red hue (longer wavelength).

atmospheric conditions can enhance either of these and toggle between the 2 i'm sure. i could be wrong of course. i just thought it was odd that it's red and blue that are mentioned.

[revil]

Originally posted by mojo
stars rotate like, really fast. the side that's rotating toward you will present a blue hue (shorter wavelength) and that which goes away presents a red hue (longer wavelength).
Are you kidding me? Doppler is just an old wives tale to scare the kiddies... no honastly, I was afaid of the doppler moster under my bed for the longest time....

[mojo]

Originally posted by revil

Are you kidding me? Doppler is just an old wives tale to scare the kiddies... no honastly, I was afaid of the doppler moster under my bed for the longest time.... this principle can actually be observed in sound as well. as a firetruck passes with sirens on, the wavelengths of the approaching truck will be virtually shorter than those as the truck moves away. yet it's at a constant (say, 400 hz or whatever).

so the hiding under the bed thing is just a fear of sirens :P