Cosmos by Carl Sagan
It is really a good book. Full of science
and imagination that can take you wonder about this universe. The book was
beautifully written. It’s really great, I really recommended all of you to buy
it! Because I’m that kind of human who
always forget what she read, I wanted to review everything that I could learned
from this book so I can remember it again. Some words I used here is original
from the book because I’m afraid if I change or rephrase those words they will
have different meaning, but there are some words too that I rephrase due to long
sentences and difficult vocabulary. So that’s why if you found some sentences
with bad grammar, it was made by me absolutely. I’m sorry, I’m just trying to
summarize this book so it will be easier to me remember this content of this
book. Oh yeah, I wrote some words from another literature as well for reference. :P .
Review:
You can measure the circumference of the
Earth by knowing the distance of 2 places and having some sticks. Eratosthenes
is an astronomer from Alexandria in 3rd century B.C. .When he was in
the southern frontier outpost of Syene, he experimented vertical stick cast no
shadow at noon on June 2. He also experimented in Alexandria vertical sticks
cast shadows near noon on June 21. But how could it be that at the same instant
there was no shadow at Syene and a substantial shadow at Alexandria. The only
possible answer was the surface of the Earth is curved. Not only that, the
greater the curvature, the greater the difference in the shadow lengths. The Sun
is so far away that its rays are parallel when they reach the Earth. Sticks
place at the different angles to Sun’s ray cast shadows of different lengths.
For the difference in the shadow lengths , the distance between Alexandria and
Syene had to be about 7 degrees along the surface of the earth or about 1/50 of
360 degrees. Eratosthenes knew the distance between Alexandrian and Syne was
approximately 800 km (he already hired a man to pace it out). 800 km times 50
is 40.000 km; so that must be the circumference of the earth. (the error is
only a few percent, it was really a remarkable achievement for 2200 years ago)
In the great dark between the stars there
are clouds of gas and dust and organic matter. Dozens of different kinds of
organic molecules have been found there by radio telescopes. The abundance of
these molecules suggests that the stuff of life is everywhere.
Artificial selection made many physical
and behavioral traits of plants and animals are inherited. Humans, for whatever
reasons, encourage the reproduction of some varieties and discourage the
reproduce of other. In the year 1185, the Emperor of Japan was a seven-year-old
boy named Antoku. Their decisive naval encounter, with the Emperor on board
ship, occurred at Danno-ura in the Japanese Inland Sea on April 24, 1185. The
Heike were outnumbered, and outmanuvered. The entire Heike battle fleet was
destroyed, only 43 women survived. These ladies-in-waiting of the imperial
court were forced to sell flowers and other favor to the fishermen near the
scene of the battle. Fishermen who are
the descendants of the Heike dress in hem and black headgear and proceed to the
Akama shrine which contains the mausoleum of the drowned Emperor. The fisherman
say the Heike samurai wander the bottom of the Inland Sea still –in the form of
crabs. There are crabs to be found here with patterns that resemble the face of
a samurai in their back (carapace) . when caught these crabs are not eaten ,
but are returned to the sea in commemoration of the doleful events at
Danno-ura. How could crab like that existed? It seems to be that humans made
the face. Because pattern in the crab’s shell are inherited, the crab with the face of samurai in their
back left more descendant than the regular crab. The more you look like a samurai, the better are
your chances of survival. Eventually, there come to be a great many samurai
crabs. This process also applied to dairy cow, dog or an ear of corn. Ten
thousand years ago, there were no domestic animal or plant. When we
domesticated the ancestors of these plants and animals, we controlled their
breeding. When we wanted a dog to help care us care for sheep, we selected
breeds that were intelligent and obedient. Eventually, there come to be many
dogs like that.
The Earth condensed out of interstellar
gas and dust some 4.6 billion years ago. We know from the fossil record that
the origin of life happened soon after, perhaps 4 billion years ago, in the
ponds and oceans of the primitive earth. In those early days, lightning and
ultraviolet light from the Sun were breaking apart the simple hydrogen-rich
molecules of the primitive atmosphere , the fragments spontaneously recombining
into more and more complex molecules. It dissolve in the oceans , forming a
kind of organic soup of gradually increasing complexity, until a molecule arose
that was able to make crude copies of itself by accident, using as building
blocks other molecules in the soup. The reason organisms are the difference in
their nucleic acid instructions. A mutation is a change in a nucleotide ,
copied into the next generation, which breeds true.
This
book told us about the discovery of the center of Solar System. As we knew, in
early day most of people believed that earth is the center of universe. It was
known as Ptolemy’s model. Then , in 1543
, Nicholas Copernicus, a Polish Catholic cleric, introduced a new model of
universe. In Nicholas’s model, Sun is the center of universe. But it annoyed
many people. In 1616 the Catholic Church placed Copernicus’ work on its list of
forbidden books “until corrected” by local ecclesiastical censors, where it
remained until 1853. Later this confrontation solved by Kepler. He introduced
Kepler’s three laws. Kepler propose that the planets were material objects made
of imperfect stuff like the Earth. And if planets were “imperfect”, why not
their orbits as well? An orbit didn’t have to be a perfect circle. His first
law of planetary motion is a planet moves in an ellipse with the Sun at one
focus. (As we know the orbit of Planet is not very ellipse but nearly circular
and neatly separated one from another. It was later explained by Sagan in next
chapter that There were probably many planets in the process of formation. The
orbits of the present planets are the orbits of the survivors of this
collisional natural selection. Those with elliptical crossing orbits tended to
collide and destroy themselves. Those with circular orbits tended to grow and
survive.) Kepler’s second law of planetary motion is Planets sweep out equal
areas in equal times. The last laws is the squares of the periods of the planes
are proportional to the cube of their average distance from the sun ( P2
= a3). This law told us the closer the planet to the Sun, its speed
will increase too.
A comet is made mostly of ice – water (H2O)ice,
a little methane (CH2) ice, and some ammonia (NH3) ice.
Striking the Earth’s atmosphere , a modest cometary fragment would produce a
great radiant fireball and a mighty blast wave. Comet also the one who
responsible of meteor shower. Meteors are the remnants of comets. In the
outermost solar system, there is a vast spherical cloud of a trillion cometary
nuclei , orbiting the sun with speed about 220 miles per hour . (If I were not
mistaken, it is called Oort Cloud ) . Most never penetrate the border marked by
the orbit of Pluto. But occasionally a passing star make a gravitational flurry
and commotion in the cometary cloud, and a group of comets finds itself in
highly elliptical orbits, plunging towards the Sun. Old comets, heated by
repeated passages near the sun, break up, evaporate and disintegrate. Some
swarm of meteors is always at the same position in the Earth’s orbit, so the
meteor shower is always observed on the same Day of every year.
Modern planetary scientist sometimes
argue that the collision of a comet with a planet might make a significant
contribution to the planetary atmosphere. For example, all the water in the
atmosphere of Mars today could be accounted for by a recent impact of small comet. Newton also believed that the
Earth’s oceans are of cometary origin, and that life is possible only because
cometary matters falls upon our planet.
++ the review will be continued at next post++
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