Chapter 2
Our Haven, Planet Earth
Abstract Planet Earth was formed from the agglomeration of solid bodies.
Earth’s iron-nickel enriched core segregated from a silicate mantle as early 30
million years after its formation 4.1–4.7 billion years ago. Earth is the third planet
in our solar system circling around the Sun in an elliptical orbit at a distance of
147–152 million kilometers. Such a distance from the Sun enables our planet’s
temperature to be hospitable to animal and plant life. Among the nine planets of
our solar system, Earth is the only one whose surface environment is adapted for
water to exist in its three states: solid, liquid and gas. The elements necessary for
life consisting essentially of oxygen, carbon, hydrogen, nitrogen and sulfur, are
also found in comets, stars and probably on other planets in the Universe. 71 % of
the Earth’s surface is covered by water, which means that when seen from space,
our home could be called the ‘‘Blue Planet’’.
The universe has expanded and cooled from an extremely hot and dense state after
the ‘‘Big Bang’’ occurred about 15 billion years ago (Hazen 2012). The term ‘‘Big
Bang’’ refers to the beginning of the Universe, when a release of energy triggered a
rapid expansion of primordial elementary particles. The regions with particles
having a high density also had a gravitational potential to attract more matter from
their surroundings and to grow even denser. Thus, the beginning of the galaxies
started as matter began to accumulate in various confined regions of the universe.
Today, our universe is also littered with blocks of dead stars. The larger and more
massive stars have exploded in supernovas and now form relics of denser stars.
Some of these massive stars have even become black holes. Other blocks and dust
have agglutinated together and contracted under gravitational forces to form hot
fireballs like the Sun. Our Sun and our solar system are located at the edge of the
Milky Way Galaxy.
R. Hekinian, Sea Floor Exploration, Springer Oceanography,
DOI: 10.1007/978-3-319-03203-0_2,
Ó Springer International Publishing Switzerland 2014
23
Our Haven, Planet Earth
Abstract Planet Earth was formed from the agglomeration of solid bodies.
Earth’s iron-nickel enriched core segregated from a silicate mantle as early 30
million years after its formation 4.1–4.7 billion years ago. Earth is the third planet
in our solar system circling around the Sun in an elliptical orbit at a distance of
147–152 million kilometers. Such a distance from the Sun enables our planet’s
temperature to be hospitable to animal and plant life. Among the nine planets of
our solar system, Earth is the only one whose surface environment is adapted for
water to exist in its three states: solid, liquid and gas. The elements necessary for
life consisting essentially of oxygen, carbon, hydrogen, nitrogen and sulfur, are
also found in comets, stars and probably on other planets in the Universe. 71 % of
the Earth’s surface is covered by water, which means that when seen from space,
our home could be called the ‘‘Blue Planet’’.
The universe has expanded and cooled from an extremely hot and dense state after
the ‘‘Big Bang’’ occurred about 15 billion years ago (Hazen 2012). The term ‘‘Big
Bang’’ refers to the beginning of the Universe, when a release of energy triggered a
rapid expansion of primordial elementary particles. The regions with particles
having a high density also had a gravitational potential to attract more matter from
their surroundings and to grow even denser. Thus, the beginning of the galaxies
started as matter began to accumulate in various confined regions of the universe.
Today, our universe is also littered with blocks of dead stars. The larger and more
massive stars have exploded in supernovas and now form relics of denser stars.
Some of these massive stars have even become black holes. Other blocks and dust
have agglutinated together and contracted under gravitational forces to form hot
fireballs like the Sun. Our Sun and our solar system are located at the edge of the
Milky Way Galaxy.
R. Hekinian, Sea Floor Exploration, Springer Oceanography,
DOI: 10.1007/978-3-319-03203-0_2,
Ó Springer International Publishing Switzerland 2014
23