Exam 4 Flashcards
(100 cards)
0
Q
Fundamental charge (e)
A
Is a charge of a single proton or electron
1
Q
Atomic mass unit (AMU)
A
Is roughly the mass of a hydrogen atom, and equals 1.66x10^-27 kilograms
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Q
Atoms are composed of..
A
Incredibly dense nuclei, consisting of protons and neutrons, surrounded by clouds of electrons
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Q
Diameter of atom’s nucleus
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Is only about 1/100,00th that of the atom itself, atoms are mostly empty space!
4
Q
Proton and neutron In an atom
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Are heavy particles of nearly equal mass (1AMU; the neutron is slightly more massive than the proton) and are believed to be composed of even smaller particles called quarks; leptons are truly fundamental particles.
5
Q
Electron
A
Has mass only 1/1830th that of the proton, and is believed to be a truly fundamental particle with no internal structure. Equal and opposite charge to the proton
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Q
Atomic number
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Number of protons; determines which type of element an atom is
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Q
Mass number
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Number of protons and neutrons, I.e., it is the total number of particles in the nucleus.
8
Q
Isotopes
A
Each element comes in a variety of isotopes. They have the same number of
Protons (atomic number) but differ in the number of neutrons (ex: iron-56 has 30 neuron, iron-58 has 32 neutron etc)
9
Q
Strong nuclear force
A
Attraction that binds protons and neutrons together against the disruptive force of electrical repulsion
10
Q
Radioactive
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Balance of protons and neutrons Is not quite right the nucleus is unstable, and will eventually break apart.
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Q
Half-life
A
Of radioactive isotope is the time period during which half of any amount of the substance disintegrates
12
Q
Louis de Broglie
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1924 suggested that, by analogy, subatomic particles also have a wave nature. The de Broglie wave associated with any particle (electron, photon, gold ball,etc) determines the probability of the particles being at a given place at a given time. If a particle has mass, it’s wavelength is inversely proportional to both its mass and speed; a photon has no mass, and it’s wavelength is inversely proportional to its energy
13
Q
Electrons in atoms can exist only..
A
In certain shells because of the electrons wave nature (split interference experiment)
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Q
When waves travel on a medium which is confined..
A
The reflected waves interfere (destructively, for the most part) with one another.
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Q
Standing waves
A
Certain frequencies that create patterns of vibration
When a wave travels back and forth within a confined medium; stable patterns. (Form the basis of all musical instruments)
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Q
Fundamental
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First standing wave (ex on a violin strong corresponding to middle C has a frequency of 256 hz)
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Q
First, overtone, second overtime
A
Have frequencies which are multiples of the fundamental
18
Q
Ideal Gas Law
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Relates the pressure (p) exerted by an enclosed body of gas to the temperature (t) of the gas and the volume (v) occupied by the gas: PV= nRT
19
Q
PV=nRT
A
n is the number of miles of gas present and R is the universal gas constant (=8.314 joules per mole per Kelvin) note that the temperature is on the absolute (Kelvin) scale.
20
Q
Avogadro’s number
A
Na=6.022x10^23 is the number of atoms or molecules contained within in mole
21
Q
Boyle’s law
A
For a fixed body of gas at a constant temperature, the pressure is inversely proportional to the volume.
22
Q
Charles Law
A
The pressure exerted by a given body of gas is directly proportional to the temperature of he gas if the volume occupied by the gas remains constant. (We found absolute zero in class using this law)
23
Q
Free electron
A
Electron floating slowly through space that has zero energy.
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Electron and energy patterns
Electron loses energy as it is attracted towards a positively-charged nucleus, an electron confined within an Atom has a negative energy. The closer the electron is the nucleus the less energy it has.
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Ground state
In the case of a hydrogen atom (which has a single electron) when the electron is in the first shell where it has the least energy.
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Atom may be excited..
Through collision with other atoms in a hot substance; during the collision an electron "jumps" to a higher energy state. Almost immediately the electron "drops" to a lower energy state. The energy lost but the electron is carried away by a photon.
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Hydrogen gas, the visible spectrum consists of three bright lines.. Balmer series of spectral lines for hydrogen
red H-alpha (wavelength=656nm)
Blue-green H-Beta (wavelength=486nm)
Violet H-gamma (wavelength=434nm)
Lines results from electrons dropping from the 3rd, 4th, and 5th shells, respectively, down to the second she'll.
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Lyman series
Lines in the ultraviolet region of the spectrum results from electrons in the second or higher shell dropping directly to the first shell (the ground state)
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Paschen series
Of lines in the infrared results from electrons in the fourth or higher shells dropping to the third shell. The complete hydrogen spectrum consists of dozens of sets of line, each resulting from electrons dripping to a particular shell from higher shells.
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Emission spectrum
Any hot low-density gas exhibits it, consisting of a series of bright colored lines (since the gas emits light only at a few specific wavelengths) but, since the pattern of electron shells is different for each element, each element has its own characteristic spectrum.
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Photoexcitation
Atom excited by absorbing a photon of light. The photon must have exactly the right energy to boost an electron to a higher shell! Consequently, atoms in low-pressure gases absorb only those wavelengths of light which they emit when heated.
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Pressure broadening
Causes the lines in the spectrum to become broader and fuzzier
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Continuous spectrum
as the density and pressure of gas increase, the electron energy level becomes "smeared out". In solids, liquids and highly compressed gasses light is emitted at all wavelengths forming the continuous spectrum.
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The rule sid spectroscopy: Kirchhoff's law/ 1
A hot liquid, or highly compressed gas exhibits a continuous spectrum. In these sense substances pressure broadening causes the lines in the spectrum to blend together, so that light is emitted at all wavelengths. Analysis of this spectrum can reveal the temperature of the light sources, but not its chemical composition!
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Rules of spectroscopy: Kirchhoff's Laws/ 2
A hot, low-density gas exhibits an emission spectrum, comprising a few specific wavelengths of light. In gaseous form, each substance has its own spectrum!
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Rules of Spectroscopy: Kirchhoff's law/ 3
A hot solid, liquid, of highly compressed gas will, when viewed behind cooler rarified gas, exhibit an absorption spectrum characteristics of the cool gas. This spectrum appears as a band of color with a superimposed pattern of dark lines at wavelengths where light has been absorbed.
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Doppler effect
As predicted by Christian Doppler in 1842, if an object is approaching the wavelength emanating from it will be shortened, and the frequency increased. If the source is receding then the wavelengths will be lengthened ( and the frequency decreased).
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Doppler shift
change in wavelength which is is simply related to the original (rest) wavelength and the speed of the source.
Ex: if a star is moving away from us at 1% the speed of the light, the wavelength of all the lines in its spectrum will be too long by 1%
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Exponential decay
However much of a radioactive substance you may have at a given time, after one half life has elapsed you will have half of that amount left.
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Electron clouds
The de Broglie wave associated with a particle determines the probability of the particles being at a given place at a given time. This is the concept of electrons as particles moving on well defined orbits is now replaced by this phenomenon.
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Within an atom, electrons can only have..
Certain well-defined energies! (Like a book shelf) never in-between.
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Mizar and Alcor in Lab
Form a optical double, this is not a true binary star system! The stay mizar is, however, a visual binary system!
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Avogadro's Law
The volume occupied by a given body of gas at a given temperature and pressure is directly proportional to the number of miles of gas.
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Radial velocity and Doppler effect
Doppler effect only involves radial velocity. That part of an object motion which is directly towards us or directly away from us! Object were to move at high speed in a circular path, a person at the center of the circle would observe no radial velocity and no Doppler effect.
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Dispersion
The actor spreading starlight (or light from any object!) into its component colors to form a spectrum.
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Prism
Dispersion of light by refracting light rays of different color through different angles.
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Diffraction grating
Produces multiple spectra via the interference phenomenon. The myriad light waves exciting the grating interference constructively in directions defined by the relation where the wavelength is the grating constant (the space between the lines)
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Hydrostatic equilibrium
Inward force of gravity at each point is exactly balanced by the internal pressure pushing outward. The sun his maintains a constant size.
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Gas pressure
A result of the rapid motions of the particles in a hot gas
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Radiation pressure
Exerted by the photons in a beam of light
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The sun produces energy..
Within its central core, where the temperature is estimated to be about 16 million Kelvin. This heat flows outward first by RADIATION (about 70% of the way) then CONVECTION to the visible surface. The photons produces within the core are constantly absorbed and re-emitted bf atoms within the Suns dense interior and take about 100,000 years to reach the surface.
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Proton-proton Cycle
Where Most of the Suns energy is produced by fusing hydrogen nuclei into helium nuclei. In the process, 0.7% of the mass is converted to energy.
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CNO (carbon-nitrogen-oxygen) cycle
Where a small fraction of the sun's energy is produced. This reaction also fuses hydrogen into helium, but Carbon nuclei are used as catalyst.
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Deuteron
(The nucleus of a deuterium, an isotope of hydrogen) cluster of one proton and one neutron. This particle forms when two protons "stick together" and weak nuclear force causes one proton to turn into a neutron.
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Positron
The "lost" positive charge is carried away by a positron; this particle has the mass of an electron but has a positive charge. A positron is a form of ANITMATTER, when it combines with an electron both are annihilated and their mass is turned entirely into energy in the form of photons.
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Neutrino
Has no
| Charge and a mass much less than that of an electron; consequently, thee particles are extremely penetrating!
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Sunspots
Appear dark only in contrast with the surrounding photosphere because they are color.
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Penumbra and Umbra (sunspots)
Where the temperature may be nearly 2000k cooler than the surrounding photosphere (Large sunspots exhibit a dark central umbra) surrounded by a grayish PENUMBRA which is a few Kelvin cooler.
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Sunspot cycle
SOLOR MINIMUM: Begging of cycle, few spots and sun less luminous. Over the next 5 or 6 years, as the faster the rotation the Suns equator "winds up" the magnetic field, spots increase and the becomes slightly more luminous. After the the SOLOR MAXIMUM: the # of spots begins to go down and after about 11 years the cycle repeats.
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Photosphere
Lowest layer of the SOLOR ATMOSPHERE; it has the highest density but then west temperature (about 6000 k)
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Chromosphere
"Sphere of colors" a thin layer which gets its appearance from its reddish color during solor eclipse
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Corona
The Suns outer "crown" extends millions of miles out into space. High temperature (1-2 million Kelvin) but a very low density. Consequently it has a very low heat content!
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Aurora
Subatomic particles escaping from the corona form the solor wind. When this wind of particles interact with earth's magnetic field.
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Solor system
```
Consist of sun and all objects bound to the sun by the force of gravity:
1 star (Sun)
Major planets (8)
Dwarf planets (5) est. 2006
Planetary satellites (100)
Minor planets (asteroids)
Comets (1,000,000,000,000)
```
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Dwarf planet
Is body orbiting the sun which is large enough to have assumed a spherical shape, but which is located within belts containing similar bodies. (Pluto)
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Kuiper belt
During the late 1900s discovered.. Belt beyond Neptune
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IAU Definition of a planet:
1. Be In orbit to the sun,
2. Have sufficient mass to assume hydrostatic equilibrium (round in shape)
3. Have "cleared the neighborhood" around its orbit
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Asteroids (minor planets)
Small bodies, typically less than fifty miles in diameter. They are composed of rock and metal (mostly iron and nickel). Being small in size, they tend to be irregular in shape.
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Ceres
Largest asteroid about 500 miles in diameter!
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Comets
Small (typically 10-20 miles) bodies composed primarily of ices (mostly water ice and dry ice) they don't grow tails until they pass inside the orbit of Mars.
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Tail of dust on comets formation
When close enough to the sun, the dry ice within the comets nucleus begins to sublimate (ex: turns into gas) The expanding gas forms a coma around the nucleus. The pressure of sunlight drives some of it away forming be tail of dust particles. Always points away from the sun!
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Oort Cloud
Jan Oort, Dutch ASTR. Suggested that a "bubble of comets surrounds the solar system it is about 50,000-100,00 AU in radius, marks the boundary of the solar system.
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Major planets orbit the sun..
In the same direction in orbits which are nearly circular and coplanar.
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Terrestrial planets
(Mercury, Venus, Earth, and Mars) are close to the sun, relatively small and dense, fairly warm and rotate slowly. Composed of metallic (mostly iron and nickel) CORES surrounded by rocky MANTLES. The larger the central core the greater the planets density. Less moons(natural satellites) or none.
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Jovian planets
(Jupiter, Saturn, Uranus, and
Neptune) are located farther from the Sun, they are much larger and more massive than the terrestrial planets, but less dense.
And they rotate rapidly; a day on Jupiter lasts less than ten hours! Consists of primarily gases( mostly hydrogen and helium) but have small central cores (gas giants); Uranus and Neptune have more of an icy composition. Lost of moons!
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Nebular Hypothesis
PROTOSTAR Small cloud of interstellar gas and dust which contacts under its own gravity. As it collapses its rotation speed increases, giving it an oblate shape. Eventually it splits into two components; a central Cody (which becomes a star) contains almost all of the ANGULAR MOMENTUM. This disk is unstable and fragments into a series of concentric rings. Then, by a gradual process of ACCRETION, the material in each ring coalesces into a planetary system.
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Differentiation
Process: early terrestrial planets were molten, allowing the denser metals to sink towards the core
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After the gas giants for formed..
All free gases were evacuated from the inner solar system. The atmosphere of venus, Earth and Mars must therefore consist of gases which were trapped within their crusts and which were real eased during volcanic eruptions.
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Measuring altitude and azimuth
Altitudes: angle between a star (or other celestial Bodies) and the point in the horizon directly below it.
Azimuth: measured along the horizon, starting due north and increasing in the eastward direction. (Ex: due both is azimuth 0 degrees, due east is 90 degrees, due south is 180 degrees)
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"Hot Jupiters"
Are Believed to have formed farther out, then spiraled inwards because of friction from leftover gas and dust I the circumstellar disk. This is not to suggest that such systems (with massive planets very close to their stars) are common, rather that they produce the largest and most easily detected, orbital peturbations and brightness changes.
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Direct observation (detection method for extrasolar planets)
Direct imaging of evolved extrasolar planets is currently just beyond the limit of our technology. Planets are very dim and would be swamped by the glare of their parent stars!
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Astrometric method (detection of exoplanets)
Indirect detection by stellar peturbations
| Observing perturbations in the stars nation, caused by its orbital motion about the center of mass of the system
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Spectroscopic method
Measure radial velocities of stars (by photographing their spectra and using the Doppler Effect) to very high precision.
Such as the white dwarf
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Transit observations (detection of exoplanets)
If the planet passes in front of its parent star (as seen from Earth) the star's apparent brightness will dim slightly. (Amateurs can do it)
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Gravitational microlens (detection of exoplanets)
a transiting planets gravitational field might act as a gravitational microlens, which would magnify the light of th background star, providing a fourth detection mechanism.
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Kepler space craft
Monitored brightness of over 145,000 stars near the constellations Cygnus looking for evidence of planets. And confirmed 1013 exoplanets. Because of Kepler data there could be as many as 40 billion Earth sizes planets orbiting in the habitual zones.
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Seismology
Is the branch of geology in which shock waves traveling through the body of he Earth's are analyzed to determine Earth's interior Structure.
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Primary (p) waves
Are longitudinal waves. They result from Compression and; like sound waves can travel
through any material.
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Secondary (s) waves
Are transverse waves. They result from material being sheared; they travel only through solids.
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Earth in layers
Crust (thin, solid Rocky)
Mantle ( thick, rocky,"plastic")
Outer core (metallic, liquid)
Inner core (metallic, solid) hotter than outer core, but the heat changes the melting point of iron.
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Continental drift:
Hypothesis by Abraham orreries 1596
Developed by Alfred webber 1912
Hypothesis for two
Centuries then developed due to the theory of PLATE TECTONICS:
1)similarities in disconnected coastlines (most notably the coastline of Europe, Africa and the Americas)
2) evidence of past glaciation in tropical regions.
3) separation of species such as elephants
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Plate tectonics
1) the earth's crust being thin and brittle is divided into segments called plates. These plates float about liquid mantle
2) heat flows from the core to the surface g convection; head slowly move (1-2 cm/year) CONVECTION CURRENTS Slowly move the crustal plates around.
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Mid-Atlantic ridge
Longest mountain range in the world, is in a region where fresh molten rock from be mantle seeps through the crust; As a result North America is slowly moving away from Europe
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Subduction zone
Place where two plates coverage; one is "crumpled up" and thrusts downward Into the mantle. Such zones are the sites of most earthquake activity.
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Magnetic field
Results from its rapid rotation and it liquid, electrically conductive outer core. Earth act sassan electromagnet and its own generator.
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Solar wind
High speed protons and electrons
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Ozone layer
Because Ozone molecules are easily broken apart by energetic photons, the ozone layer absorbs most of the Suns ultraviolet light protecting life here on the surface.
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Van Allen Belts
Surround the earth that some solar wind particles get trapped in
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Aurora
Solar winds wind funneled towards the Earth's north and south magnetic poles, where they may collisionally excite air molecules.
