Here are
some interesting points from the
first chapter:
If
we scale things down so the sun is
only an inch away, the next
nearest star [Proxima Centauri]
would be four miles away.
Proxima
Centauri [right, photographed
by Hubble Space Telescope
WFPC2] is part of the Alpha
Centauri star system, the
closest star system and
planetary system to Earth's
Solar System at 4.37
light-years from the Sun. It
is a triple star system, the
other two stars as Sun-like
and form a binary.
Proxima Centauri has two known
planets, Proxima b, an
Earth-sized exoplanet in the
habitable zone discovered in
2016; and proxima c, a
super-Earth, which is possible
surrounded by a huge ring
system, discovered in 2019.
α Centauri is the
designation given to Alpha
Centauri by Johann Bayer in
1603.
Alpha Centauri C was
discovered in 1915 by Robert
T. A. Innes.
Alpha Centauri is listed
in Ptolemy's star catalogue.
In his time it was visible
from Alexandria, Egypt, but
due to precession it can no
longer be seen from that
latitude.
The binary nature of
Alpha Centauri AB was
recognised in 1689 by Jean
Richaud.
...
[20 December
2020] "SETI Detected a Strange
Radio Signal From Proxima
Centauri"
The Moon's diameter = 3,500 km
The Moon's mean distance from
Earth is 384,000 km
Saturn has seventeen
82 known satellites/moons.
Saturn has
82 known moons, 53 of which
have formal names. In
addition, there is evidence of
dozens to hundreds of moonlets
with diameters of 40–500
meters in Saturn's rings,
which are not considered to be
true moons.
Titan, the largest moon
[seen in the bottom left of
the above image], comprises
more than 90% of the mass in
orbit around Saturn, including
the rings. Saturn's
second-largest moon, Rhea, may
have a tenuous ring system of
its own, along with a tenuous
atmosphere.
The asteroids are below 1000 km
across.
Meteors - grains of sand-size.
Meteorites - larger,
crater-causing, more like
asteroids.
Light-year = 9.46 million million
km.
Pole star - 680 light-years away
100,000 million stars in our
galaxy.
Nebulae = patches of cloud and
dust / Latin for "clouds".
Andromeda's [bared] spiral galaxy
is over 2 million light-years
away.
Apart from a few of the nearest
systems, all galaxies are moving
away from us; the universe is
expanding.
Proxima
Centauri [right, photographed
by Hubble Space Telescope
WFPC2] is part of the Alpha
Centauri star system, the
closest star system and
planetary system to Earth's
Solar System at 4.37
light-years from the Sun. It
is a triple star system, the
other two stars as Sun-like
and form a binary.
