Sky and Telescope - October 2017 - 4
SPECTRUM
by Peter Tyson
The Stone Tree
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O C T O B E R 2 0 17 * S K Y & T E L E S C O P E
EDITORIAL
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PE TER T YSON / S&T
west, I stumbled upon an enormous petrified tree trunk. The trunk at
one end was so fat I couldn't have wrapped my arms around it, and it
retained every detail of its gnarled, mahogany-colored "bark." As I fingered the former wood, I could easily picture primeval ants scuttling
up and down it, going about their obscure lives.
The trunk was so out of place in that treeless expanse that it seemed to have
fallen from the sky. Yet I knew from the geologic formation it lay in that it
belonged there just as unassailably as the widely spaced ocotillo and creosote
plants that now claimed the semi-arid landscape around it. The stone tree was
eroding out of the Aguja Formation, which is roughly 75 million years old. When
the tree was alive, it stood in a bald cypress-like forest on the edge of a shallow
seaway that extended from the Arctic Ocean to the Gulf of Mexico.
As I knelt there marveling at this throwback to another age, it occurred to me
that, despite the almost incomprehensible dissimilarity between the landscape
today and way back then, only time separates the fossil tree from its living counterpart. No other variables need change. If I could just
wind the clock back 75 million years to the final day
in the Late Cretaceous when this tree stood erect, I
could lean against it (careful not to crush any ants)
and behold the likes of duck-billed dinosaurs, giant
crocodilians, and imposing cycads and tree ferns.
The same conceit came to me while writing this
month's cover story, which concerns what will happen to our solar system as the Sun swells into a red
giant over 6 billion years from now (page 22). Only
Only time separates this fossil
time
- or Time, if you will - divides our beautiful
tree from its living analogue.
blue Earth from a world that's but a burnt ember
hosting no life of any sort. As with my musing on the stone tree, one need not
adjust a single other factor. Simply leap forward 6 billion years - if you could -
and no matter where you are on the planet, that spot, in that distant eon, will
have long since been scorched to a cinder. Earth will have become a Venus.
This is not cause for gloom but for fascination - and perspective. Thought
experiments like these remind us that our presence in the stream of Time,
despite all the importance it holds for us humans, is but a ripple. In the grand
scheme of things, we and all we pride ourselves on are, geologically or cosmologically speaking, akin to passing whims, here now and gone a moment later.
Astronomy offers infinite opportunities for such chastening
reflection, and I find that to be one of its great draws.
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Sky and Telescope - October 2017
Table of Contents for the Digital Edition of Sky and Telescope - October 2017
Contents
Sky and Telescope - October 2017 - Cover1
Sky and Telescope - October 2017 - Cover2
Sky and Telescope - October 2017 - 1
Sky and Telescope - October 2017 - Contents
Sky and Telescope - October 2017 - 3
Sky and Telescope - October 2017 - 4
Sky and Telescope - October 2017 - 5
Sky and Telescope - October 2017 - 6
Sky and Telescope - October 2017 - 7
Sky and Telescope - October 2017 - 8
Sky and Telescope - October 2017 - 9
Sky and Telescope - October 2017 - 10
Sky and Telescope - October 2017 - 11
Sky and Telescope - October 2017 - 12
Sky and Telescope - October 2017 - 13
Sky and Telescope - October 2017 - 14
Sky and Telescope - October 2017 - 15
Sky and Telescope - October 2017 - 16
Sky and Telescope - October 2017 - 17
Sky and Telescope - October 2017 - 18
Sky and Telescope - October 2017 - 19
Sky and Telescope - October 2017 - 20
Sky and Telescope - October 2017 - 21
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Sky and Telescope - October 2017 - 24
Sky and Telescope - October 2017 - 25
Sky and Telescope - October 2017 - 26
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Sky and Telescope - October 2017 - 30
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Sky and Telescope - October 2017 - Cover3
Sky and Telescope - October 2017 - Cover4
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