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TIMESCALES
Timescales
relating to human development and the terrestrial environment
| Phenomenon |
Timescale* |
| Astronomical |
|
| Giant
comets injected into short-period orbits |
100,000
yr |
| Orbital
evolution of Chiron |
100,000
yr |
| Significant
evolution of zodiacal cloud |
1,000
– 50,000 yr |
| Lifetime
of giant comet |
10,000
– 30,000 + yr |
| Interval
since maximum extent of last ice age |
18,000
yr |
| End
of continental glaciation |
10,000
yr |
| Lifetime
of typical meteor stream |
500-5,000
yr |
| Significant
evolution of giant comet debris |
1,000-5,000
yr |
| Significant
evolution of Taurid meteor stream |
1,000-5,000
yr |
| Lifetime
of normal active comet |
300-1,500
yr |
| Cultural |
|
| Beginning
of homo sapiens |
40,000
yr |
| Beginning
of food production and domestication |
10,000
yr |
| First
civilizations; irrigation; cuneiform texts |
5,000
yr |
| Constellation
building (main epoch) |
5,000
yr |
| Oldest
celestial myths |
3,000-5,000
yr |
| Main
epoch of megalith and ziggurat building |
3,000-5,000
yr |
| Earliest
calendars |
3,000
yr |
| Well
documented history |
less
than 2,000 yr |
*Very
approximate. The slowness of human development during the ice
age contrasts noticeably with the speed of cultural evolution
following its end. There is much overlap of astronomical and
cultural timescales, and indeed the zodiacal cloud and Taurid
meteors are visible even now, while Encke’s comet is just
below naked-eye visibility. In antiquity with the complex of
debris much more active, it is likely that the prime comet,
lesser comets, and debris were regularly visible in the zodiac,
and associated with fierce annual fireball showers and occasional
impacts.
In seeking
evidence of the ancient turbulent sky, we should not necessarily
expect descriptions, perhaps four or five thousand years old,
to be given in modern scientific terms. We do not seek comets
tracking along the zodiac but gods wandering along a celestial
river; rather than evanescent patches of light we should seek
temporary celestial islands; rather than fireball swarms and
a Tuguska impact we expect celestial thunderbolts hurled in
anger; and in tales of the world’s end, we should be alert
for indications that celestial catastrophe came specifically
out of the constellation Taurus the Bull, or in more remote
epochs, because of the evolution of the meteor orbits, out of
the neighbouring constellation Aries the Ram.
Fred Hoyle
and Chandra Wickramasinghe
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