Re: The Return of The Thagomizer... :-)

[Dann Pigdon <dannj@alphalink.com.au>]

Richard W. Travsky writes:
> > ARGH! Of course. It will continue to get brighter and brighter. The end 
> > of life due to overheating is scheduled for one billion years in the 
> > future.
>
> So, how much "dimmer" or "less bright" was the sun during the days of
> the dinos? 
>
> What effect, if any would this have had on dinosaur evolution? Eyesight,
> for example?

The sun is thought to be around 4.5 billion years old. 

If it started out 70% as bright as it is now, that means it's increased in 
initial brightness by a further 40% (ie. it's now 140% of the brightness it 
began at). That's a 1% increase in initial brightness every 112.5 million 
years on average (assuming a simple linear trend). 

If my thumbnail calculations are correct, then the sun has only increased 
(relative to it's initial brightness) by a further 0.58% since the end of 
the Cretaceous. Dinosaurs probably lived through less than a 2% increase in 
brightness due to increased solar output during their entire reign on earth. 

Super-volcanic eruptions or major bolide impacts probably had a much greater 
effect of apparent solar brightness (and in the opposite direction). 

___________________________________________________________________ 

Dann Pigdon
GIS / Archaeologist              geo cities.com/dannsdinosaurs
Melbourne, Australia             heretichides.soffiles.com
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