Sky & Telescope - December 2023 - 65
BOOK REVIEW by Peter Tyson
Up Close and Personal
UNDER ALIEN S IES: A Sightseer's Guide to the Universe
Philip Plait, PhD
W. W. Norton & Co., 2023
336 pages, ISBN 978-0-393-86730-5
US$30.00, hardcover
PHIL PLAIT, well-known author of
the blog, newsletter, and book Bad
Astronomy, has wondered since he was
a kid what celestial objects would look
like up close. What if you were nearby
in a spaceship or - if the object had a
solid surface - standing on it? After he
earned his PhD in the 1990s and began
giving public talks on astronomy, he
found that many others had the same
question. So he wrote this book.
The Moon
Plait starts with our nearest neighbor.
The Apollo landings gave us Earthlings
some notion of what it's like to be on
the lunar surface, but Plait seasons our
understanding. He reminds us that even
when the Sun blazes at midday, the sky
would remain black, because there's
little atmosphere to light up the sky.
When the Sun sets, the light disappears
instantly. " Just bang, night, " he writes.
And we'd have to contend with the temperature
change, which can swing from
250°F at noon to -200°F before dawn.
Thanks again to Apollo, we've seen
Earth from the Moon. But have we
considered how bright earthshine would
be on our satellite? As Plait observes,
Earth is about 14 times bigger and three
times more reflective than the Moon, so
reading by Earthlight when our planet is
" full " would be a cinch. And how about
watching a total solar eclipse from the
Moon? Earth would be much larger in
the sky than the Sun, so you wouldn't
see as much of the solar corona during
totality. " That's okay, " Plait writes,
" because this eclipse has something no
Earth-bound stargazer
could ever see: a world
with an atmosphere blocking
the Sun. "
Saturn
Plait then shuttles you to
Mars and the asteroids
before heading out to
Saturn. The Cassini mission
gave us breathtaking
closeups of the rings, but
Plait takes you even closer.
If you were in a spacecraft
right at the outer edge of the outermost
ring, he says, that edge wouldn't appear
curved when you looked along it but
perfectly straight. " The rings are circles,
but they're circles 170,000 miles across, "
he writes (he likes emphasis). They're
also incredibly thin - in most spots,
only 40 feet thick.
If your hypothetical spaceship
arrived at that outer rim edge-on to
Saturn, the rim would appear as a onedimensional
line in the sky. But rise just
up over that rim and you'd see a vast
plain of icy boulders stretching towards
the gas giant. " Perspective plays havoc
with your eyes and brain, " Plait writes,
noting that the boulders shrink with
distance toward Saturn, but the lack of
air means they're just as sharp far away
as nearby. Imagine if your ship flew into
Saturn's shadow, with the Sun on the
opposite side of the planet from you.
The rings would fill the sky in a grand,
whitish arc - except where the world's
75,000-mile-wide shadow erased them,
leaving pure black.
Far-away Worlds
As an astronomer, Plait makes use of
the latest scientific thinking, of course.
But since we have no close-up images of
deep-sky objects, he has no choice but
to speculate on near views
of objects beyond our solar
system. Readers will have
to judge for themselves
how successful he is.
Plait steers us to the
TRAPPIST-1 system of
exoplanets, to planetary
nebulae, and to starforming
regions like
the Orion Nebula. He
explains how someone on
a planet orbiting two stars
would enjoy " sunsrise "
and " sunsset, " and how traveling near a
black hole would be " trippy to see, one
of the weirdest sights in your life. " And
how about stargazing on a planet orbiting
a star near the core of a globular
cluster? After dark, Plait says, instead
of the several thousand stars visible at
a dark-sky site on Earth, you'd see tens
of thousands of suns overhead, some of
them so bright as to make you squint.
On the surface around you, multiple
shadows of different lengths would
shoot out on every side.
It's a delightful prospect, but globulars
formed so long ago, Plait notes, that
it's possible they have no rocky planets
at all. In providing such caveats, he
enhances our trust in him as our guide.
Altogether, Plait does a fine job taking
you right up to wondrous objects. As
he writes, " We may not know precisely
what it's like to fall into a black hole
or visit a star as it's forming, but our
understanding of astronomy, physics,
mathematics, and more can feed our
minds, allowing us to imagine with
great accuracy and remarkable detail
what it would be like if we were there. "
¢ PETER TYSON wishes the galaxycrossing
spaceships Plait imagines were
real and he had a seat on one.
sk yand tele scope .o r g * DECEMBER 2023 65
https://skyandtelescope.org/
Sky & Telescope - December 2023
Table of Contents for the Digital Edition of Sky & Telescope - December 2023
Contents
Sky & Telescope - December 2023 - Cover1
Sky & Telescope - December 2023 - Cover2
Sky & Telescope - December 2023 - 1
Sky & Telescope - December 2023 - Contents
Sky & Telescope - December 2023 - 3
Sky & Telescope - December 2023 - 4
Sky & Telescope - December 2023 - 5
Sky & Telescope - December 2023 - 6
Sky & Telescope - December 2023 - 7
Sky & Telescope - December 2023 - 8
Sky & Telescope - December 2023 - 9
Sky & Telescope - December 2023 - 10
Sky & Telescope - December 2023 - 11
Sky & Telescope - December 2023 - 12
Sky & Telescope - December 2023 - 13
Sky & Telescope - December 2023 - 14
Sky & Telescope - December 2023 - 15
Sky & Telescope - December 2023 - 16
Sky & Telescope - December 2023 - 17
Sky & Telescope - December 2023 - 18
Sky & Telescope - December 2023 - 19
Sky & Telescope - December 2023 - 20
Sky & Telescope - December 2023 - 21
Sky & Telescope - December 2023 - 22
Sky & Telescope - December 2023 - 23
Sky & Telescope - December 2023 - 24
Sky & Telescope - December 2023 - 25
Sky & Telescope - December 2023 - 26
Sky & Telescope - December 2023 - 27
Sky & Telescope - December 2023 - 28
Sky & Telescope - December 2023 - 29
Sky & Telescope - December 2023 - 30
Sky & Telescope - December 2023 - 31
Sky & Telescope - December 2023 - 32
Sky & Telescope - December 2023 - 33
Sky & Telescope - December 2023 - 34
Sky & Telescope - December 2023 - 35
Sky & Telescope - December 2023 - 36
Sky & Telescope - December 2023 - 37
Sky & Telescope - December 2023 - 38
Sky & Telescope - December 2023 - 39
Sky & Telescope - December 2023 - 40
Sky & Telescope - December 2023 - 41
Sky & Telescope - December 2023 - 42
Sky & Telescope - December 2023 - 43
Sky & Telescope - December 2023 - 44
Sky & Telescope - December 2023 - 45
Sky & Telescope - December 2023 - 46
Sky & Telescope - December 2023 - 47
Sky & Telescope - December 2023 - 48
Sky & Telescope - December 2023 - 49
Sky & Telescope - December 2023 - 50
Sky & Telescope - December 2023 - 51
Sky & Telescope - December 2023 - 52
Sky & Telescope - December 2023 - 53
Sky & Telescope - December 2023 - 54
Sky & Telescope - December 2023 - 55
Sky & Telescope - December 2023 - 56
Sky & Telescope - December 2023 - 57
Sky & Telescope - December 2023 - 58
Sky & Telescope - December 2023 - 59
Sky & Telescope - December 2023 - 60
Sky & Telescope - December 2023 - 61
Sky & Telescope - December 2023 - 62
Sky & Telescope - December 2023 - 63
Sky & Telescope - December 2023 - 64
Sky & Telescope - December 2023 - 65
Sky & Telescope - December 2023 - 66
Sky & Telescope - December 2023 - 67
Sky & Telescope - December 2023 - 68
Sky & Telescope - December 2023 - 69
Sky & Telescope - December 2023 - 70
Sky & Telescope - December 2023 - 71
Sky & Telescope - December 2023 - 72
Sky & Telescope - December 2023 - 73
Sky & Telescope - December 2023 - 74
Sky & Telescope - December 2023 - 75
Sky & Telescope - December 2023 - 76
Sky & Telescope - December 2023 - 77
Sky & Telescope - December 2023 - 78
Sky & Telescope - December 2023 - 79
Sky & Telescope - December 2023 - 80
Sky & Telescope - December 2023 - 81
Sky & Telescope - December 2023 - 82
Sky & Telescope - December 2023 - 83
Sky & Telescope - December 2023 - 84
Sky & Telescope - December 2023 - Cover3
Sky & Telescope - December 2023 - Cover4
https://www.nxtbook.com/nxtbooks/aas/st_202410
https://www.nxtbook.com/nxtbooks/aas/st_202409
https://www.nxtbook.com/nxtbooks/aas/st_202408
https://www.nxtbook.com/nxtbooks/aas/st_202407
https://www.nxtbook.com/nxtbooks/aas/st_202406
https://www.nxtbook.com/nxtbooks/aas/st_202405
https://www.nxtbook.com/nxtbooks/aas/st_202404_qr
https://www.nxtbook.com/nxtbooks/aas/st_202404
https://www.nxtbook.com/nxtbooks/aas/st_202403
https://www.nxtbook.com/nxtbooks/aas/st_202402
https://www.nxtbook.com/nxtbooks/aas/st_202401_aus
https://www.nxtbook.com/nxtbooks/aas/st_202401
https://www.nxtbook.com/nxtbooks/aas/st_202312_aus
https://www.nxtbook.com/nxtbooks/aas/st_202312
https://www.nxtbook.com/nxtbooks/aas/st_202311
https://www.nxtbook.com/nxtbooks/aas/st_202310
https://www.nxtbook.com/nxtbooks/aas/st_202309
https://www.nxtbook.com/nxtbooks/aas/st_202308
https://www.nxtbook.com/nxtbooks/aas/st_202307
https://www.nxtbook.com/nxtbooks/aas/st_202306
https://www.nxtbook.com/nxtbooks/aas/st_202305
https://www.nxtbook.com/nxtbooks/aas/st_202304
https://www.nxtbook.com/nxtbooks/aas/st_202304_qr
https://www.nxtbook.com/nxtbooks/aas/st_202303
https://www.nxtbook.com/nxtbooks/aas/st_202302
https://www.nxtbook.com/nxtbooks/aas/st_202301
https://www.nxtbook.com/nxtbooks/aas/st_202212
https://www.nxtbook.com/nxtbooks/aas/st_202211
https://www.nxtbook.com/nxtbooks/aas/st_202210
https://www.nxtbook.com/nxtbooks/aas/st_202209
https://www.nxtbook.com/nxtbooks/aas/st_202208
https://www.nxtbook.com/nxtbooks/aas/st_202207
https://www.nxtbook.com/nxtbooks/aas/st_202206
https://www.nxtbook.com/nxtbooks/aas/st_202205
https://www.nxtbook.com/nxtbooks/aas/st_202204
https://www.nxtbook.com/nxtbooks/aas/st_202203
https://www.nxtbook.com/nxtbooks/aas/st_202202
https://www.nxtbook.com/nxtbooks/aas/st_202201
https://www.nxtbook.com/nxtbooks/aas/st_202112
https://www.nxtbook.com/nxtbooks/aas/st_202111
https://www.nxtbook.com/nxtbooks/aas/st_202110
https://www.nxtbook.com/nxtbooks/aas/st_202109
https://www.nxtbook.com/nxtbooks/aas/st_202108
https://www.nxtbook.com/nxtbooks/aas/st_202107
https://www.nxtbook.com/nxtbooks/aas/st_202106
https://www.nxtbook.com/nxtbooks/aas/st_202105
https://www.nxtbook.com/nxtbooks/aas/st_202104
https://www.nxtbook.com/nxtbooks/aas/st_202103
https://www.nxtbook.com/nxtbooks/aas/st_202102
https://www.nxtbook.com/nxtbooks/aas/st_202101
https://www.nxtbook.com/nxtbooks/aas/skywatch_2021
https://www.nxtbook.com/nxtbooks/aas/st_202012
https://www.nxtbook.com/nxtbooks/aas/st_202011
https://www.nxtbook.com/nxtbooks/aas/st_202010
https://www.nxtbook.com/nxtbooks/aas/st_202009
https://www.nxtbook.com/nxtbooks/aas/st_202008
https://www.nxtbook.com/nxtbooks/aas/st_202007
https://www.nxtbook.com/nxtbooks/aas/st_202006
https://www.nxtbook.com/nxtbooks/aas/st_202005
https://www.nxtbook.com/nxtbooks/aas/st_202004
https://www.nxtbook.com/nxtbooks/aas/st_202003
https://www.nxtbook.com/nxtbooks/aas/st_202002
https://www.nxtbook.com/nxtbooks/aas/st_202001
https://www.nxtbook.com/nxtbooks/aas/st_201912
https://www.nxtbook.com/nxtbooks/aas/st_201911
https://www.nxtbook.com/nxtbooks/aas/st_201910
https://www.nxtbook.com/nxtbooks/aas/st_201909
https://www.nxtbook.com/nxtbooks/aas/st_201908
https://www.nxtbook.com/nxtbooks/aas/st_201907
https://www.nxtbook.com/nxtbooks/aas/st_201906
https://www.nxtbook.com/nxtbooks/aas/st_201905
https://www.nxtbook.com/nxtbooks/aas/st_201904
https://www.nxtbook.com/nxtbooks/aas/st_201903
https://www.nxtbook.com/nxtbooks/aas/st_201902
https://www.nxtbook.com/nxtbooks/aas/st_201901
https://www.nxtbook.com/nxtbooks/aas/st_201812
https://www.nxtbook.com/nxtbooks/aas/st_201811
https://www.nxtbook.com/nxtbooks/aas/st_201810
https://www.nxtbook.com/nxtbooks/aas/st_201809
https://www.nxtbook.com/nxtbooks/aas/st_201808
https://www.nxtbook.com/nxtbooks/aas/st_201807
https://www.nxtbook.com/nxtbooks/aas/st_201806
https://www.nxtbook.com/nxtbooks/aas/st_201805
https://www.nxtbook.com/nxtbooks/aas/st_201804
https://www.nxtbook.com/nxtbooks/aas/st_201803
https://www.nxtbook.com/nxtbooks/aas/st_201802
https://www.nxtbook.com/nxtbooks/aas/st_201801
https://www.nxtbook.com/nxtbooks/aas/st_201712
https://www.nxtbook.com/nxtbooks/aas/st_201711
https://www.nxtbook.com/nxtbooks/aas/st_201710
https://www.nxtbook.com/nxtbooks/aas/st_201709
https://www.nxtbook.com/nxtbooks/aas/st_201708
https://www.nxtbook.com/nxtbooks/aas/st_201707
https://www.nxtbook.com/nxtbooks/aas/st_201706
https://www.nxtbook.com/nxtbooks/aas/st_201705
https://www.nxtbook.com/nxtbooks/aas/st_201704
https://www.nxtbook.com/nxtbooks/aas/st_201703
https://www.nxtbook.com/nxtbooks/aas/st_201702
https://www.nxtbook.com/nxtbooks/aas/st_201701
https://www.nxtbook.com/nxtbooks/aas/st_201612
https://www.nxtbook.com/nxtbooks/aas/st_201611
https://www.nxtbook.com/nxtbooks/aas/st_201610
https://www.nxtbook.com/nxtbooks/aas/st_201609
https://www.nxtbook.com/nxtbooks/aas/st_201608
https://www.nxtbook.com/nxtbooks/aas/st_201607
https://www.nxtbook.com/nxtbooks/aas/st_201606
https://www.nxtbook.com/nxtbooks/aas/st_201605
https://www.nxtbook.com/nxtbooks/aas/st_201604
https://www.nxtbook.com/nxtbooks/aas/st_201603
https://www.nxtbook.com/nxtbooks/aas/st_201602
https://www.nxtbook.com/nxtbooks/aas/st_201601
https://www.nxtbook.com/nxtbooks/aas/st_201512
https://www.nxtbook.com/nxtbooks/aas/st_201511
https://www.nxtbook.com/nxtbooks/aas/st_201510
https://www.nxtbook.com/nxtbooks/aas/st_201509
https://www.nxtbook.com/nxtbooks/aas/st_201508
https://www.nxtbook.com/nxtbooks/aas/st_201507
https://www.nxtbook.com/nxtbooks/aas/st_201506
https://www.nxtbook.com/nxtbooks/aas/st_201505
https://www.nxtbook.com/nxtbooks/aas/st_201504
https://www.nxtbook.com/nxtbooks/aas/st_201503
https://www.nxtbook.com/nxtbooks/aas/st_201502
https://www.nxtbook.com/nxtbooks/aas/st_201501
https://www.nxtbook.com/nxtbooks/aas/st_201412
https://www.nxtbook.com/nxtbooks/aas/st_201411
https://www.nxtbook.com/nxtbooks/aas/st_201410
https://www.nxtbook.com/nxtbooks/aas/st_201409
https://www.nxtbook.com/nxtbooks/aas/st_201408
https://www.nxtbook.com/nxtbooks/aas/st_201407
https://www.nxtbook.com/nxtbooks/aas/st_201406
https://www.nxtbook.com/nxtbooks/aas/st_mars
https://www.nxtbook.com/nxtbooks/aas/st_201405
https://www.nxtbook.com/nxtbooks/aas/st_201404
https://www.nxtbook.com/nxtbooks/aas/st_201403
https://www.nxtbook.com/nxtbooks/aas/st_201402
https://www.nxtbook.com/nxtbooks/aas/st_201401
https://www.nxtbook.com/nxtbooks/aas/st_201312
https://www.nxtbook.com/nxtbooks/aas/st_201311
https://www.nxtbook.com/nxtbooks/aas/st_201310
https://www.nxtbook.com/nxtbooks/aas/st_201309
https://www.nxtbook.com/nxtbooks/aas/st_201308
https://www.nxtbook.com/nxtbooks/aas/st_201307
https://www.nxtbook.com/nxtbooks/aas/st_201306
https://www.nxtbook.com/nxtbooks/aas/st_201305
https://www.nxtbook.com/nxtbooks/aas/st_201304
https://www.nxtbook.com/nxtbooks/aas/st_201303
https://www.nxtbook.com/nxtbooks/aas/st_201302
https://www.nxtbook.com/nxtbooks/aas/st_201301
https://www.nxtbook.com/nxtbooks/aas/st_201212
https://www.nxtbook.com/nxtbooks/aas/st_201211
https://www.nxtbook.com/nxtbooks/aas/st_201210
https://www.nxtbook.com/nxtbooks/aas/st_201209
https://www.nxtbook.com/nxtbooks/aas/st_201208
https://www.nxtbook.com/nxtbooks/aas/st_201207
https://www.nxtbook.com/nxtbooks/aas/st_201206
https://www.nxtbook.com/nxtbooks/aas/st_201205
https://www.nxtbook.com/nxtbooks/aas/st_201204
https://www.nxtbook.com/nxtbooks/aas/st_201203
https://www.nxtbook.com/nxtbooks/aas/st_201202
https://www.nxtbook.com/nxtbooks/aas/st_201201
https://www.nxtbook.com/nxtbooks/aas/st_201112
https://www.nxtbook.com/nxtbooks/aas/st_201111
https://www.nxtbook.com/nxtbooks/aas/st_201110
https://www.nxtbook.com/nxtbooks/aas/st_201109
https://www.nxtbook.com/nxtbooks/aas/st_201108
https://www.nxtbook.com/nxtbooks/aas/st_201107
https://www.nxtbook.com/nxtbooks/aas/st_201106
https://www.nxtbook.com/nxtbooks/aas/st_201105
https://www.nxtbook.com/nxtbooks/aas/st_201104
https://www.nxtbook.com/nxtbooks/aas/st_201103
https://www.nxtbook.com/nxtbooks/aas/st_201102
https://www.nxtbook.com/nxtbooks/aas/st_201101
https://www.nxtbook.com/nxtbooks/aas/st_201012
https://www.nxtbook.com/nxtbooks/aas/st_201011
https://www.nxtbook.com/nxtbooks/aas/st_201010
https://www.nxtbook.com/nxtbooks/aas/st_201009
https://www.nxtbook.com/nxtbooks/aas/st_201008
https://www.nxtbook.com/nxtbooks/aas/st_201007
https://www.nxtbook.com/nxtbooks/aas/st_201006
https://www.nxtbook.com/nxtbooks/aas/st_201005
https://www.nxtbook.com/nxtbooks/aas/st_201004
https://www.nxtbook.com/nxtbooks/aas/st_201003
https://www.nxtbook.com/nxtbooks/aas/st_201002
https://www.nxtbook.com/nxtbooks/aas/st_201001
https://www.nxtbookmedia.com