I have a question about what I think is Canopus (SE sky when viewed from Sydney).
Some preliminaries
I'M A RANK BEGINNER ...
I don't have a GOTO scope, nor do I use RA/Declination coordinates in locating objects.
To the naked eye and through my bino's and scope (what I think is) Canopus appears to continuously change colour (almost looks like the exterior lights of a plane except the object doesn't move and it's there night after night).
Is this some weird atmospheric effect or am I seeing things or what ??
Yep, if a bright star is low down on the horizon you are looking at it through heaps of turbulent air. The air refracts the light and effectively gives you a varying degree of chromatic abberation and as a result the colour will change.
That is why you try to look at objects at least 30 degrees above the horizon if possible. The amount of air you are looking through is greatly reduced and so is its effect giving you a better, more stable image.
Canopus isn't rising until early in the morning, so it may not be the one you're looking at.
What time of day are you looking?
As Rob said, it's the light diffracting through the atmosphere that causes it to change colour, and the "seeing"/atmospheric turbulance that's causing it to twinkle.
Thanks for the feedback. You're right, it was relatively low so atmospherics is the answer.
I was viewing around 9pm EST looking roughly SSE to SE - I'm just using star charts and trying to line things up so could easliy have got picked the wrong star *BUT* the effect is pretty cool !!
Canopus rises at 21:42 tonight at my location in Queensland, , as Paul has said Achernar is quite high by 21:00, so IMO you are probably on the money in thinking that it is Canopus
to the site!
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