Universe and Solar System
Origin of the Universe Theories:

Big Bang Theory (13.7 bya): States that the universe began from an extremely hot, dense point
and has been expanding and cooling ever since.

Inflation Theory: Hypothesis that immediately after the Big Bang, the universe expanded
extremely rapidly, much faster than the speed of light, before slowing down.

Steady State Theory / Infinite Universe Theory or Continuous Creation: Proposed by Hermann
Bondi, Thomas Gold, and Sir Fred Hoyle, this theory suggests the universe is expanding and
has an infinite age, with no beginning or end. Matter is continually created and destroyed,
maintaining a constant density as new galaxies form and old ones die.

Creation Myth: According to the Genesis of the Bible’s Old Testament, the creation of the
entire cosmos took place in six days.
Event in the Big Bang Theory
10-43 seconds
Also known as the PLANCK ERA
This is the closest that current Physics can get
to the absolute beginning of time.
The universe is thought to be incredibly hot, dense, and turbulent, with the very fabric of
space and time turned into a roiling morass.
10-35 seconds
Also known as the GRAND UNIFICATION ERA
At the end of which the “superforce” began to break apart into the constituent forces we see
today.
10-32 seconds
The energy dumped into the universe by the end of inflation led to the appearance of
particles of matter
Einstien’s equation: E= mc2.
10-11 seconds
Also known as the Electroweak Era, when the last 2 fundamental forces still unified with one another
– electromagnetism and the weak nuclear force – finally split leaving and the universe with the 4
separate forces in the present –day universe.
10-6 seconds
it became cool enough to allow the familiar particles of today’s matter, protons & neutrons, to form
from their constituents, known as quarks.
200 seconds
protons & neutrons started to come together to form nuclei, the charged cores of atoms.
300,000 years
the universe cooled to about 1,0000C – cool enough for electrons to pair up with nuclei to form the
first atom.
0.5 – 1b years
The force of gravity started to pull together huge regions of relatively dense cosmic gases, forming the
vast, swirling collections of stars we now call galaxies.
9B years
The force of gravity trying to slow the cosmic expansion began to lose out to the anti-gravitational
effect “ dark energy” a mysterious force which has been accelerating the cosmic expansion ever since
Origin of the Solar System Theories:

Kant-Laplace Nebular Hypothesis: Proposed by Immanuel Kant and Pierre-Simon Laplace, this
hypothesis suggests that the solar system formed from a great cloud of gas and dust (nebula)
that collapsed under gravity, spun more rapidly, flattened into a pancake shape, and then
formed the sun and planets from contracting local regions.

Planetesimal Hypothesis: Proposed by Thomas Chowder Chamberlin and Forest Ray Moulton,
this theory states that a collision of a star with our sun created huge tides and erupted matter.
Smaller masses cooled to become solid bodies called planetesimals, which then grew into
planets by absorbing other planetesimals as their orbits crossed.

Tidal Theory: Proposed by Sir James Hopwood Jeans and Harold Jeffreys, this theory suggests
planets were formed from material torn out of the sun due to the gravitational attraction of a
passing massive star.
Cosmology Terms:

Cosmology: The study of the universe, including its properties, structure, and evolution.

Universe: All of space and time (spacetime) and its contents, including planets, moons, minor
planets, stars, galaxies, intergalactic space, and all matter and energy. It is also sometimes
called cosmos.
Sun and Solar System Formation:

Cosmological Nucleosynthesis: The process where the Sun was formed, creating Hydrogen
atoms, some of which fused into Helium.

Stellar Nucleosynthesis: Created Carbon, Nitrogen, Oxygen, and other heavier elements
(mostly metals) that eventually formed the planets.

Coalescence: Gravitational condensation of gaseous particles leading to the formation of stars
and gaseous planets (Jupiter, Saturn, Uranus, and Neptune).

Accretion: Gravitational condensation of solid particles leading to the formation of rocky,
metallic entities (Mercury, Venus, Earth, and Mars).
Sun Features and Activities:

Sun: A normal main sequence star, the largest object in the solar system, containing over
99.8% of the region’s total mass. Its surface temperature is 5,800 K, and its core temperature
is 15.6 million Kelvin.

Sunspots: Areas that appear dark on the Sun's surface because they are cooler than other
parts.

Solar Flares: Sudden explosions of energy caused by the tangling, crossing, or reorganizing of
magnetic field lines near sunspots.

Photosphere: The innermost layer of the Sun's atmosphere, considered the "Sun's Surface" or
"Sphere of Light," where visible light is emitted. Sunspots are found here.

Chromosphere: The "Color Sphere" of the Sun, which glows red and has temperatures ranging
from 4,000 to 50,000°C. Gas jets shoot out, and it is visible during a solar eclipse.

Corona: The outermost layer of the Sun's atmosphere, which can reach 1,000,000°C and is
visible during an eclipse.
Planetary Motion:

Revolution: The movement of the 8 planets around the Sun through an elliptical path (orbit),
also referred to as a solar year.

Rotation: The spinning motion of planets on their imaginary axis, taken as equal to a solar
day.
Models of the Universe:

Geocentric Model: Proposed by Claudius Ptolemy, this model states that Earth is the center of
the universe, and all celestial bodies (planets, moon, sun, and stars) move around it.

Heliocentric Model: Proposed by Nicolaus Copernicus, this model states that the Sun is the
center of the cosmos, and planets (Mercury, Venus, Earth and Moon, Mars, Jupiter, Saturn)
move in their own orbits around it, while stars are fixed in the sky. It also notes that Earth has
three motions: daily rotation, annual revolution, and annual tilting off its axis.
The Planets (General Characteristics):

Terrestrial Planets: Rocky materials (e.g., Mercury, Venus, Earth, Mars).

Gas Giants: Mostly made of gases (e.g., Jupiter, Saturn, Uranus, Neptune).
Specific Planets:

Mercury: 1st planet from the Sun. Resembles Earth’s Moon with impact craters. Has almost no
atmosphere and no moons. Its day is very slow (58.65 days), and its revolution is 88 Earth
days.

Venus: 2nd planet from the Sun. Covered by thick, rapidly spinning clouds. Atmosphere mainly
CO2, N, and sulfuric acid droplets. No moons. Its day (243 days) is longer than its year (225
Earth days). Hottest planet due to greenhouse effect.

Earth: 3rd planet from the Sun. Appears blue and green from space with clouds. Has one
moon. Rotation is 23 hours, 56 minutes, and revolution is 365.25 days.

Mars: 4th planet from the Sun. Appears red due to iron oxide in its soil. Has two irregular
moons (Phobos and Deimos). Its axis tilt and day length are similar to Earth's. Features include
wind, volcanoes, floodwaters, and giant impact craters, including Olympus Mons, the largest
volcano in the solar system.

Jupiter: 5th planet from the Sun. A gas giant with 63 moons and several rings, often called a
"mini-solar system." Mostly hydrogen, helium, and methane atmosphere. Has the highest
gravity in the solar system. Features the Great Red Spot, a hurricane-like storm existing for at
least 100 years.

Saturn: 6th planet from the Sun. A gas giant with a large system of rings and yellow-gold
bands in its atmosphere. Has 60 moons. Its ring system is the most extensive and complex in
our solar system.

Uranus: 7th planet from the Sun. Blue-green color due to methane gas. Has 27 moons. Its axis
is tilted, making it appear to rotate on its side.

Neptune: 8th planet from the Sun. Blue color due to methane in its atmosphere. A gas giant
with 13 moons. It is the farthest planet from the sun for a 20-year period every 248 Earth
years due to Pluto's unusual elliptical orbit.
Earth and Earth Subsystems
Earth as the Only Habitable Planet - Life-Supporting Characteristics:

Water: Exists mostly in liquid state, acts as a universal solvent and medium for chemical
processes, regulates Earth's temperature due to high heat capacity, and expands/becomes
lighter when frozen.

Atmosphere and its composition: Contains important gases like Nitrogen (N2) for protein
synthesis, Oxygen (O2) for cellular respiration, and Carbon Dioxide (CO2) for photosynthesis.

Energy, Space, and Time: Life flourishes due to solar energy, Earth's ideal distance from the
Sun for sufficient heat, and the long periods for Earth's formation.

Other Factors: Stability of the sun, Earth’s electromagnetic field, geologic activity, and the
ability to recycle and reform energy resources.
Earth Systems/Spheres:

Lithosphere: The solid outer part of Earth, composed of the crust and the uppermost mantle.
o
Crust: The outermost layer of the Earth where we live. It is split into two parts:
Continental Crust (made of igneous rocks) and Oceanic Crust (sedimentary and basalt
rocks). Composed of Oxygen (46%), Silicon (28%), Aluminum (8%), Iron (6%),
Magnesium (4%), Potassium (2.3%), Sodium (2.1%), and Calcium (2.4%).
o
Mantle: The largest layer of Earth, composed of very hot, dense rock, primarily Silicon
dioxide (45.3%), Magnesium Oxide (38.39%), Iron II Oxide (7.82%), Aluminum Oxide
(4.19%), and Calcium Oxide (3.36%).
o


Lithosphere (Mantle layer): Top, cooler layer of the mantle made of dense
rock (iron and nickel).

Asthenosphere: Bottom, liquid layer of the mantle made of iron and nickel.
Core: Composed of 86% Iron (Fe), 4% Nickel (Ni), and 10% light elements like Oxygen
(O) and Sulfur (S).
Atmosphere: Mixture of gases that cover the Earth.


o
Just Formed Earth Atmosphere: Very warm hydrogen (H2) and helium (He) molecules
that moved fast enough to escape Earth’s gravity.
o
Young Earth Atmosphere: Volcanoes released gases like H2O (steam), ammonia (NH3),
nitrogen (N2), hydrogen sulfide (H2S), hydrogen chloride (HCl), and sulfur dioxide
(SO2).
o
Current Earth Atmosphere: Plants take in carbon dioxide (CO2) and release oxygen
(O2); animals take in oxygen (O2) and release carbon dioxide (CO2).
Hydrosphere: All the water on Earth.
o
Meteoric Water: From asteroids and comet fragments that fell on Earth's surface; the
frozen water melted due to high planet temperatures.
o
Volcanic Water: From water vapor released during Earth's out-gassing, followed by
condensation and precipitation.
o
Hydrologic/Water Cycle: The continuous movement of water on, above, and below
the surface of the Earth.
o
Earth’s Water Composition: 97% Oceans/Marine (high salt concentration) and 3%
Freshwater (low dissolved salts).
o
Aquatic Biomes: Classified by salt/mineral content: Marine/Oceanic Biomes (at least
3.5% dissolved salts) and Freshwater Biomes (0.05% or less salt concentration).
Biosphere: Region of Earth where life exists, also referred to as Biomes.
o
Biomes: Ecosystems largely determined by latitude/geographic position, altitude, and
elevation, classified as terrestrial or aquatic.
o
Terrestrial Biomes: Influenced by solar radiation, weather, and climate (temperature
range, precipitation). Classified by dominant vegetation: Forests (trees and woody
plants), Grasslands (grasses/monocots and herbs), and Deserts (shrubs and
succulents).