This is the last (currently) of some articles I intended as a connected series. If you have the time, you may appreciate visiting the others first (assuming you haven’t already):
- We are a way for the Cosmos to know itself
- Asking the right questions
- Total solar eclipse: coincidence?
- The Antikythera mechanism
This is part 5: When life began there were no Baily’s beads.
I suggested recently that the total solar eclipse may have been responsible for instigating intelligent life on our planet, but, at the time, I hadn’t looked that closely at the numbers.
The window in which a ‘total solar eclipse’ can be seen from the Earth is about 100 million years. We’re halfway through that span; in about 50 million years, the Moon will have retreated so far from us that it will be too small in the sky to completely eclipse the Sun.
Were we to consider the proportion of time the solar eclipse ‘window’ has been available to all life on our planet to this point, we’re looking at about 1:100; ie a total solar eclipse has only been visible (assuming something existed to see it!) for one hundredth of the time that life has existed.
But we have to narrow the field somewhat; limit it to land life only (I think it’s fair to assume that simple multicellular life would be incapable of appreciating the heavens!). Life crawled from the seas less than 500 million years ago (see the ‘life timeline’ on the right). This brings the ratio down to 1:10.
The land life around for nine-tenths of this period would not have been able to experience a total solar eclipse; the moon was simply too big in the sky.
As Scientific American puts it:
It is very likely that a scientifically minded Tyrannosaurus Rex never got to see the circle of fire, or Bailey’s [sic] Beads in an eclipse.
The ‘human timeline’ on the left shows that most of the advances our species has made have been within about the last two million years; a total solar eclipse will have been available to us throughout this entire period.
Imagine being one of those early humans, standing on some long-ago plain, and experiencing the wonder of a total eclipse; wouldn’t it make you stop and think that maybe those all-too-familiar lights in the sky were something more?