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SOLAR SYSTEM, image, solar system, image, image, ORIGIN OF THEUNIVERSE -…
SOLAR SYSTEM
MODELS
GEOCENTRIC MODEL
Presented by
Claudius Ptolemy.
This theory also explained that the earth is being revolved around by the five planets: Mercury, Venus, Mars, Jupiter, and Saturn. Planets move with respect to fixed stars, with changing brightness, changing speed, and
having retrograde motion.
States that the earth is the center of the Solar System
Ancient Greeks, such as the famous Philosopher, Aristotle, believed this theory of Claudius.
This idea of his was rejected because some planets seem to move backwards (in retrograde) instead of in their usual forward motion around Earth.
HELIOCENTRIC MODEL
Presented by
Nicolaus Copernicus
The heliocentric hypothesis was based on seven general principles. These
principles stated that:
The center of Earth is the center of the lunar sphere—the orbit of the moon
around Earth
All the spheres rotate around the sun, which is near the center of the universe
The distance between Earth and the sun is an insignificant fraction of the
distance from Earth and Sun to the stars, so parallax is not observed in the stars
The stars are immovable – their apparent daily motion is caused by the daily
rotation of Earth
Earth is moved in a sphere around the sun, causing the apparent annual
migration of the sun. Earth has more than one motion
Earth's orbital motion around the sun causes the seeming reverse in direction of
the motions of the planets
Celestial bodies do not all revolve around a single point
States that the Sun is the center of the Solar System
Each heavenly body inhabited a sphere, encapsulating the sun
Epicycles still required, but smaller.
Mathematical elegance and accuracy of the algorithm increased acceptance rate
A
representation
of an idea, an object, or even a process that is used to
described and explain a phenomenon that
cannot be experienced directly
Solar System models illustrate the relative positions and motions of the planets and moons in the Solar System that have been built for
centuries.
Solar System Models help for further studies and observation of the Solar System; If the Theories will increase relevance or otherwise.
THEORIES ABOUT THE ORIGIN OF THE SOLAR SYSTEM
NEBULAR HYPOTHESIS
Stars form in massive and dense clouds of
molecular
hydrogen
—
Giant Molecular Clouds
(GMC).
These clouds are gravitationally unstable, and matter coalesces within them to be smaller denser clumps, which then rotate, collapse, and form stars.
Star formation
is a complex process, which always produces a gaseous
protoplanetary disk
(proplyd) around the young star.
The
formation of giant planets
is a more complicated process.
It is thought to occur
beyond the
frost line
, where planetary embryos mainly are made of various types of ice.
They are several times more massive than in the inner part of the
protoplanetary disk.
Some embryos appear to continue to grow and eventually reach 5–10 Earth masses
Planets were formed out of a cloud of material associated with a youthful sun, which was slowly rotating. The friction and collision of particles led to the formation of a disk shaped cloud & the planets were formed through the process of accretion.
Most accepted theory
PLANETESIMAL THEORY
Theory developed by
T. C. Chamberlin
and
F. R. Moulton
in the early part of
the
20th cent.
Encounter
or
Collision
Theory - a star passes close by or actually collides with
the sun
Caused huge tides were raised on the surface; some
of this erupted matter was torn free.
and, by a cross-pull from the star, was thrust into
elliptical orbits around the sun.
The smaller masses quickly cooled to become solid bodies,
called planetesimals.
As their orbits crossed, the larger bodies grew by absorbing the
planetesimals, thus becoming planets.
TIDAL THEORY
Proposed by
James Jeans
and
Harold Jeffreys
in
1918
A
variation of the planetesimal concept:
A huge tidal wave resulted by a passing star was driven to a long filament and ended detaching from the principal mass
Gaseous materials condensed, forming into shapes of planets.
Had objections though: The angular momentum problem is
not fully explained.
PROTOPLANET THEORY
Proposed
in
1944
by
C. F. von Weizsacker
and modified by
Gerald P. Kuiper
.
Replaced
the original nebular hypothesis of Kant and Laplace
Replaced the Planetesimal Theory
The rapidly rotating nebulas will develop large whirlpools or vortexes at various places on the
disk of nebular material.
Each of these great whirlpools might then have collected the
surrounding material by gravitational attraction, thus forming a protoplanet.
It is believed that nine protoplanets –one for each of the present-day planets—
were formed, and these were originally much larger than the finished planet.
Whirlpools formed inside vortex, became spinning disks then evolved into the moons of the planets.
The solar system is the sun and everything that orbits around it.
It includes the planets and their moons as well as numerous asteroids and comets.
The planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, dwarf planets such as Pluto, dozens of moons and millions of asteroids, comets and meteoroids.
The main idea of the solar system was proposed by the Polish astronomer Nicolaus Copernicus
ORIGIN OF THEUNIVERSE
