Basic TL:
Hadean Æon -4500 to -3800 Million Years
Archæn Æon -3800 to -2500 Million Years
Proterozoic Æon
Vendian Period -600 to -542 Million Years
Phanerozoic Æon
Paleozoic Era -542 to -251 Million Years
Mesozoic Era -251 to -65 Million Years
Cenozoic Era -65 to +130 Million Years
Nothezoic Era +130 to +630 Million Years
Postnothozoic Era +630 to +1080 Million Years
Postmarian Æon
Macrozoic Era +1080 to + 1530 Million Years
Microzoic Era +1530 to +1890 Million Years
Paravenerian Æon +1890 to +5500 Million Years
Fornaxian Æon +5500 to +5567 Million Years
Cinisian Æon 5567 Million Years +
Any comments? Questions? This is a group work, but Seth Deitch set out the basics first.
Um... is there an explanation of these?
ReplyDeleteDoug M.
>is there an explanation of these
ReplyDeletePlate tectonics and Solar System
evolution, I think.
Andreas Morlok
Yes, I did pick up on that, thanks. And "postmarian" and "paravenerian" are pretty self-explanatory. I rather like "fornaxian".
ReplyDeletePerhaps explanation is the wrong word. Is there a _description_ of these?
Doug M.
Hey guys,
ReplyDeleteIt's a little sketchy still and I think people are getting ahead of ourselves once more. Oy. keeping something like this from going off rails is damned ahrd, esp when I'm not online over the weekends.
Cenozoic ends with the mammals losing their grip on the majority of megafauna and there only being one major, extended continent (a couple minor ones). They have some competitors after the Quaternary Extinction, but nada that would topple their collective position.
The Nothozoic ends when the supercontinent shatters. The PostNoth is a bit vague as yet.
You guys figured out the Postmarian and Paravenerian. The Macrozoic age is the last stand of macroscopic multicellular organisms on earth. The Microzoic is the last gasp of even the microscopics at the surface.
The Fornaxian is when old Sol has gone red giant. The Cinisian is afterwards when earth is crispy.
Are the Postmarian and Paravenerian aeon's meant to overlap?
ReplyDeleteGraeme.
Nope. My mistake. I'll fix it shortly.
ReplyDeleteWill,
ReplyDeleteAre you sure about the dates for those last two?
Here's a paper from 1993:
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1993ApJ...418..457S
That may be dated, but I haven't been able to find anything more recent. And if it's correct, Sun will stay on the Main Sequence for about 6.5 billion more years.
Over this time, it will gradually brighten to about 2.2 times its present luminosity. That's about as much sunlight as Venus gets now, so a runaway greenhouse catastrophe should occur well before that. The paper suggests it will happen after a billion years or so, but I think climate science has advanced since 1993 much faster than astrophysics, so that point probably needs revisiting.
Note that the ascent of the red giant branch takes a while -- several hundred million years. During this time the Sun is a subgiant. The Earth is really hot and lifeless, but still has an atmosphere.
The Earth's fate is indeed to become a cinder cruising just outside the chromosphere of the Sun. All of its atmosphere -- even if it's much denser than Venus' -- will eventually be blown away by the sheer mad heat of the Sun. At its largest, the Sun will be around 1 au in diameter; however, mass loss during its ascent to the red giant phase will cause the planets to spiral outwards, with the Earth ending up outside the current orbit of Mars. The Sun's maximum heat output will be around 5200 L, which will raise Earth's surface temperature to around 1800 K.
-- Hmm, "cinder" doesn't quite cover that... I'd expect there to be lakes or even seas of molten material. Silicon dioxide will still be solid but many other minerals will not. Iron oxide, for instance, melts around 1600 K. Come to think of it, Cinisian Earth might have some atmosphere after all -- wisps of metal and mineral vapor.
Anyway, FYI.
Also: if there isn't a runaway greenhouse, plate tectonics should slow down noticeably after another couple of billion years. I don't think they'll stop before the sun leaves the main sequence, but they will slow. There's only so much internal heat...
cheers,
Doug M.