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Reading Material 1.2

The Solar System consists of the Sun and everything orbiting it, including 8 planets, dozens of moons, and millions of smaller objects like asteroids and comets. There are several theories for how the Solar System formed. The leading theory is the Nebular Hypothesis, which states that the system developed from a large cloud of gas and dust that collapsed over time, with most material forming a protostar at the center that became our Sun. Small objects in the leftover disk began sticking together through gravity to form larger protoplanets, eventually creating the planets we see today. The planets are divided into terrestrial planets like Earth that are rocky, and gas giants like Jupiter that are mostly made of hydrogen and helium and

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42 views2 pages

Reading Material 1.2

The Solar System consists of the Sun and everything orbiting it, including 8 planets, dozens of moons, and millions of smaller objects like asteroids and comets. There are several theories for how the Solar System formed. The leading theory is the Nebular Hypothesis, which states that the system developed from a large cloud of gas and dust that collapsed over time, with most material forming a protostar at the center that became our Sun. Small objects in the leftover disk began sticking together through gravity to form larger protoplanets, eventually creating the planets we see today. The planets are divided into terrestrial planets like Earth that are rocky, and gas giants like Jupiter that are mostly made of hydrogen and helium and

Uploaded by

Camilla Raine Pecundo
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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ADVANCED READING MATERIAL FOR EARTH SCIENCE

Reading Material #1.2:

The Solar System:


The Solar System is a system of a Sun and the objects that move around it. According to NASA, our solar system consists of our star,
the Sun, and everything bound to it by gravity – 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. Beyond our own solar system, we have
discovered thousands of planetary systems orbiting other stars in the Milky Way.

Modern Theories about the origin of the solar system:


1. Encounter Hypothesis
One of the earliest theories for the formation of the planets was called the
encounter hypothesis. In this scenario, a rogue star passes close to the Sun
about 5 billion years ago. Material, in the form of hot gas, is tidally stripped
from the Sun and the rogue star. This material fragments into smaller lumps
which form the planets. This hypothesis has the advantage of explaining why
the planets all revolve in the same direction and provides an explanation for
why the inner worlds are denser than the outer worlds.
However, there are two major problems for a theory of this type. One is that
hot gas expands, not contracts. So, lumps of hot gas would not form planets.
The second is that encounters between stars are extremely rare, so rare as
to be improbable in the lifetime of the Universe (15 billion years).

2. Nebular Hypothesis
This states that the solar system developed out of an interstellar
cloud of dust and gas, called a nebula. This theory best
accounts for the objects we currently find in the Solar System
and the distribution of these objects. The Nebular Theory would
have started with a cloud of gas and dust, most likely left over
from a previous supernova. The nebula started to collapse and
condense; this collapsing process continued for some time. The
Sun-to-be collected most of the mass in the nebula’s center,
forming a Protostar.
A protostar is an object in which no nuclear fusion has occurred,
unlike a star that is undergoing nuclear fusion. A protostar
becomes a star when nuclear fusion begins. Most likely the next
step was that the nebula flattened into a disk called the
Protoplanetary Disk; planets eventually formed from and in this
disk.
3. Protoplanet Hypothesis
How did the Solar System’s planets come to be? The leading theory is something known as the “protoplanet hypothesis”, which essentially
says that very small objects stuck to each other and grew bigger and bigger — big enough to even form the gas giants, such as Jupiter.
About 4.6 billion years ago, as the theory goes, the location of today’s Solar System was nothing more than a loose collection of gas and
dust — what we call a nebula. (Orion’s Nebula is one of the most famous examples you can see in the night sky.)
Then something happened that triggered a pressure change in the center of the cloud, scientists say. Perhaps it was a supernova
exploding nearby, or a passing star changing the gravity. Whatever the change, however, the cloud collapsed and created a disc of
material, according to NASA.
The center of this disc saw a great increase in pressure that eventually was so powerful that hydrogen atoms loosely floating in the cloud
began to come into contact. Eventually, they fused and produced helium, kickstarting the formation of the Sun.
The Sun was a hungry youngster — it ate up 99% of what was swirling around, NASA says — but this still left 1% of the disc available
for other things. And this is where planet formation began.

The Planets in our Solar System:

Terrestrial Planets:
The planets Mercury, Venus, Earth, and Mars are called terrestrial because they have a compact, rocky surface like Earth.
The Gas Giants and Jovian Planets:
A gas giant is a large planet mostly composed of helium and/or hydrogen. These planets, such as Jupiter, Saturn, Uranus, and Neptune
in our solar system, don’t have hard surfaces and instead have swirling gases above a solid core. Gas giant exoplanets can be much
larger than Jupiter, and much closer to their stars than anything found in our solar system.

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