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Samenvatting boek systeem aarde 1
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Een samenvatting van de hoofdstukken uit het boek Earth Porttrait of a Planet die bij systeem aarde 1 horen.
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By: siemvankammen • 3 year ago
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PreludeVan centrum tot oppervlak, heeft onze planeet een kern, mantel en korst. We leven op het
oppervlak van de korst die de lithosfeer wordt genoemd. Het is een 100-150 km dikke korst.
Duidelijke grenzen scheiden deze korst in platen. Ze bewegen heel langzaam over een
zachter deel van de mantel dat de asthenosfeer wordt genoemd.
De aarde heeft interne processen die worden
aangedreven door de warmte in de aarde en
externe processen die worden aangedreven door
de energie van de zon.
Geologist made a geologic time scale to refer to
specific portions of geologic time.
Chapter 1
The universe contains of two basic entities: energy and matter which consists of atoms and
has a mass, this substance makes up objects.
The solar system doesn’t only contain planets it also contains other objects such as:
- Moons: a moon is a solid object that orbits a planet. They vary in size, composition
and surface characters. In our solar system each planet except Mercury and Venus
have one moon or more.
, - Asteroids: an asteroid is a relatively small rocky or metallic object that orbits the sun.
- Dwarf planets: are known as asteroids and Kuiper Belt objects with a diameter
greater than 900km.
- Comets: a ball of ice and dust that orbits the sun.
A light-year is the distance that light travels in one year (9.5 trillion km).
Doppler effect is the phenomenon in which the frequency of wave energy changes when a
moving source of wave energy passes an observer.
Light is a form of electromagnetic radiation and the Doppler effect also applies to light.
When a light source moves away from you (lower frequency) the light will become redder.
When a light source moves closer to you (higher frequency) the light will become bluer.
Astronomers found that the light coming to earth from other galaxies displayed a red shift.
According to the Doppler effect this means that the galaxies are moving away from the Earth
at an immense speed. This theory is now known as the expanding Universe theory.
The Big Bang:
According to scientist the Big Bang was an enormous explosion that formed the universe.
Before this explosion all matter and energy were packed into an infinitesimally small point
called a singularity.
At first the universe consisted entirely of energy and atoms did not exist. Within a few
seconds the universe had cooled down enough that hydrogen atoms started to form.
When the universe was 3 minutes old, the temperature had cooled down enough for
hydrogen to fuse together to form helium.
The formation of new atoms (mostly helium and hydrogen) in the first few minutes is called
the Big Bang nucleosynthesis because this happened before any stars existed.
As the universe expanded and cooled further, atoms and molecules slowed down and
formed vast gas clouds called nebulae.
Inside the nebulae, gravity caused gas and ice to molt together into flattened disks with
round centers. The centers became protostars and because of the rising temperature which
caused fusion reactions and the protostars became real stars.
When a giant star explodes, it produces a supernova.
The nebulae of which the first stars were formed only consisted of small atoms, because
during the big bang nucleosynthesis only small atoms were formed.
The heavier elements were formed during fusion reactions in the stars. This process is called
the stellar nucleosynthesis. Some of these atoms are emitted by the star during its lifetime
(stellar wind) but most only escape when a star dies.
Most very large atoms (bigger than iron) can only be formed with high temperatures in a
supernova explosion (supernova nucleogenesis).
According to the nebular condensation theory of the solar system formation, planets
developed from the rings of gas and dust around the proto sun. The gas and dust condensed
into planetesimals (tiny solid pieces of rock and metal that collect in a planetary nebula),
which then clumped together to form protoplanets and the planets as we now know.
The inner rings became the terrestrial planets and the outer rings became the giant planets.
The moon was formed when a protoplanet collided with the earth.
, Chapter 2
When something, for example a satellite, makes its way through the universe on its way to
our solar system it passes different stages.
For most of its journey it travels through interstellar space, the region between stars. This
region hosts a vacuum.
At a certain point our satellite will start to feel the, then still weak, gravity of the sun. Then it
will float through the Oort Cloud. The Oort Cloud is a cloud of icy objects that orbit the sun in
a region outside of the heliosphere.
After the Oort Cloud our object will enter the heliosphere. This is a bubble-like region in
space where solar wind has blown away most interstellar atoms and is technically the ‘edge’
of our solar system.
Then it will travel through the Kuiper Belt, a ring of icy objects that orbit our sun outside the
orbit of Neptune. After we’ve passed Neptune we will cross into interplanetary space.
In the inner part of our solar system we find the 4 terrestrial planets. Mars, Earth, Venus and
Mercury.
When the satellite nears the earth, it starts to detect the earth’s magnetic field. The
magnetic field is a dipole meaning it has two ends: a north pole and a south pole.
The north pole of an imaginary magnetic bar lies near the south geographic pole of the earth
and the south pole lies near the north geographic pole.
The earth’s magnetic field serves as a shield against solar-wind particles which can be
dangerous to life forms. The region that is protected from this radiation is called the
magnetosphere.
At the Van Allen radiation belts the magnetic field gets stronger and traps cosmic rays and
solar-wind particles that were too fast and penetrated the outer magnetic field. This means
the Van Allen belts also serve as a line of defense that protects the earth from dangerous
radiation.
Not all particles are trapped and when they get closer to earth, they can interact with gas
atoms which causes them to glow, an aurorae.
Then we will go into orbit around the earth and floats through our atmosphere.
The density of the atmosphere progressively increases as we get closer to the earth.
Researchers generally consider the top of the atmosphere at about 600km.
There are 4 layers in our atmosphere. Starting with the lowest one: troposphere,
stratosphere, mesosphere and the thermosphere. The boundaries between each of these
layers are named of the underlying layer. The boundary between the troposphere and the
stratosphere is called the tropopause.
The earth’s surface exists 30% of dry land and 70% of surface water. Our earth has
topography, variations in its elevation and bathymetry, the variations in depth of the ocean
floor.
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