Sirius crazy twinkling?

[orionbman]

I noticed the other night when I was out that Sirius was twinkling like crazy. I put the telescope on it and there was a kalidoscope of color twinkling off it. Red, green, blue, yellow. What causes this? Why were other stars I observed, although twinkling some what, weren't showing like Sirius?

 

[nevers]

The simple answer - Atmospheric disturbances.

 

[harmonicaman]

The complex answer - "Twinkle Twinkle Little Star"; an educational article written by Bill Plait at Bad Astronomy.com - it's worth a link...:<br /><br />http://www.badastronomy.com/bitesize/twinkle.html

 

[Saiph]

the main reason Sirius twinkles so much, and through colors, is it's brightness. Say atmospheric turbulence causes a star to dim by 20%, 30% and 50%. For a dim star, it's hard to tell bettween 20% and 30%...so shifts of that small scale are muted. For a bright star, the eye can easily distinguish between them, and so we can notice those.<br /><br />Also, it takes a decent amount of light to enter the eye for it to discern color, so only brght stars provide easily discernable color changes.<br /><br />Note: Percentages are just off the top of my head for the example. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[iron_sun_254]

Also, this is more pronounced when a star is closer to the horizon because the light passes through more atmosphere.

 

[siarad]

I think you're right about the brightness as we have colour vision only in the centre of our eyes & normally see stars in monchrome peripheral vision only.<br />I sometimes go colour blind which leaves a grey disc about the size of a word in my central vision.

 

[kimb68]

I seem to recall reading in Burnham's Celestial Handbook that some historical accounts indicate that Sirius was sometimes perceived as red by the ancients. Burnham has various theories for why this might have been. It's definitely worth a read.

 

[Saiph]

<blockquote><font class="small">In reply to:</font><hr /><p>The trouble is, according to current theories of stellar evolution, there is no way that Sirius B could have evolved from a red giant to its present white dwarf stage in a matter of a few thousand years. Therefore, the Dogon ought not to have any knowledge of its previous color.<p><hr /></p></p></blockquote><br /><br />The author didn't think this through...since knowledge of the stars previous color would be an observational source...i.e. the Dogon (and anybody else) observed the star to be red. Just cause you don't know <i>why</i> it's red, doesn't mean you can't know it's red. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>