Planet-Planet Solar System Livable
Aria Judhistira Home (Amateur Astronomers Association of London)
Imagine the Earth's resources are depleted. Environment is no longer convenient for
membeludaknya populated along with the number of people. So, where next we
will be? "Secretly," the experts are busy looking for the answer.
Residential area (habitable zone) is defined as a place within a distance range
certain of its parent star that allows the presence of water, in liquid form, in
surface of the planet's retinue. In theory, the conditions that allow water met
in this phase will support the emergence of the "seeds of life". Water in liquid form
is the best solvent that will allow the course of the reaction of various
elements and chemical compounds that exist. Therefore it is not surprising that the presence of water
in this phase will be a sign that gives hope for the emergence of a
forms of life.
Giant planets outside our solar system orbiting the Sun setipe stars
(Extrasolar planets) have so far not enter into consideration as a place unfit for human habitation
for life as we know it. If so, then where we can
put please? The only reasonable answer is in the natural satellites of the planet-owned
The gas planet.
In our solar system, the greater the mass of a gas planet, the greater the total mass
their satellites. That is, could have gas planets outside the solar system with
size is much larger than the size of Jupiter will have a satellite
The planet Mars, for example. Natural satellites chosen as the site of the "promise" not
despite the fact that many of these planets are gas giants that are in
"Habitable zone" of their parent stars (1 to 1.9 AU, 1 AU of about 150 million kilometers).
The next question is what conditions would have to have alternative housing
is to be able to provide carrying capacity for life?
The presence of atmospheric
In order to become an ideal place to live, these satellites should have an atmosphere.
Earth, the only other planet in the Solar System that has so far able to provide the carrying capacity
for growth and development of life forms, has a moderate atmosphere. Month
as the Earth's natural satellite with a mass of about 1/100 times the mass of the Earth would not have
atmosphere at all. From here, the satellites of extrasolar planets should be much greater
than the size of our moon, at least the size of the largest satellites of the planets
giants in the solar system.
Layer of air that surrounds the satellite surface is useful in protecting life
surface of the bombardment of harmful radiations from space, in addition to
also act as guardians of the surface temperature to stay comfortable. To be
maintain the existence of the atmosphere in the long term, the release of gas-
atmospheric gases, primarily in the upper atmosphere, have been slow. This can be achieved when
temperature of the atmosphere there is quite low or quite massive satellites in question
so it will have the speed off (escape velocity) are great to be able to
restrain the escape of gas atoms in the layer above it.
Reflecting on what has been happening on Earth, scientists believe that the atmosphere in
green planet was formed from the gases released from the bowels of the Earth through the activity
volcanic. Fuller explanation seems necessary given the current composition of the atmosphere
"Dispose" of oxygen to the air, while in the atmosphere is about 21 percent of this gas.
What makes the Earth's atmosphere has changed drastically? From which oxygen is to be
"Gas of life" for aerobic organisms come from?
Two theories have been proposed to explain how the formation of oxygen. Which
The first is through a process fotodisosiasi, the breakdown of water vapor by ultraviolet light
which would generate free hydrogen and oxygen by the reaction: 2H2 + 2H2O Ultraviolet
Unfortunately, because of the light gases such as hydrogen atom will easily escape the gravitational
Earth, this process will not be able to provide abundant amounts of oxygen as
we now meet.
The second theory proposes that no other source of oxygen is life itself,
through a process called photosynthesis, where carbon dioxide and water react to
to form carbohydrates and oxygen, 6CO2 + 6H2O C6H12O6 + 6O2
It is estimated, 99 percent of the total amount of oxygen is released into the atmosphere from the time-
the early Earth is derived from the photosynthesis process, while only 1 percent of the
derived from fotodisosiasi.
Geological activity
Geological activity on Earth were probably due to the availability of internal heat sources in the central
Earth. Geological activity is required in running the carbonate-silicate cycle that will
control the temperature of the atmosphere as a whole. The absence of this geological activity would
create a cooling environment to be a perpetual ice age.
Carbonate-silicate cycle, as we encounter took place on Earth, starting with the reaction
between carbon dioxide and silicate minerals. Reaction products formed will carry over
to sea, and stored in the form of carbonate deposits. Furthermore, through the activity
geological processes such as tectonics, carbonate deposits may reach the lithosphere (layer
rock) in the Earth's surface. On arrival at the Earth's surface, carbonate deposits would have
heating and converted back into carbon dioxide through volcanic activity.
The presence of carbon dioxide in the atmosphere will withstand the heat received from the Sun
back off to maintain a stable temperature at the surface. Internal heat source for
planets like Earth comes from the decay of radioactive isotopes. The more massive the planet
concerned, the longer the carbonate-silicate cycle that can take place.
On the satellites of extrasolar planets, in addition to the decay of radioactive isotopes, internal heat sources
they have also obtained from the heating process due to the tides (tidal heating).
Io, one of the largest satellite of Jupiter, is an example. Most satellites in between the
four Galilean satellites are likely to experience tidal heating and making celestial
natural accompaniment to the planet's most active volcanic activity in our Solar System. Large-small
tidal heating is strongly influenced by various factors, such as satellites and planetary mass
its parent, the internal structure of the satellite is concerned, the size of the long half-axis and
kelonjongan orbit satellites, as well as distant-satellite orbit is close to other satellites (if any)
in the system.
The length of the day
The computer model suggests that any satellites orbiting extrasolar
can achieve synchronization planets orbit, meaning the time it takes for the satellite
one rotates together with the lapse of time it takes for one-time around
parent planet (the revolution). According to the definition of a more assertive synchronization orbit, the satellite rotation period
is also exactly the same as the planet's rotation period.
The same event has occurred on our moon. During this face of the Moon that is facing
Earth is the same face, the result of tidal interactions over hundreds of millions
years ago. One day in the month to go on longer than on Earth, ie for more
approximately 27 Earth days (the same as the time it takes for one-time around Earth).
A more extreme case occurred in the only satellite of Pluto, Charon. In addition to having
rotation period is equal to the period of its orbit, the rotation period with Charon also
rotation period of Pluto (about six Earth days). As a result, except that the face of Charon
The same is always facing Pluto, Charon also faces can only be enjoyed from
surface of one hemisphere of Pluto. Imagine, in the evening in one hemisphere will Pluto
Charon is always decorated with the face, while other parts of the night in will never
see the appearance of the satellite.
Assuming that the satellites are owned by extrasolar planets have an orbital period of 1.7 -
16 days of Earth as well as the largest satellites in our solar system, the calculation
carried Stephen Dole (1960) showed that the satellite with an atmosphere like
Earth had been unable to provide a place that can support life as
rotation period of more than four days. In this condition, changes in surface temperature
satellite will be very large.
The size of the orbit
The size of the orbit, in this half-axis length and kelonjongan, highly influential
against the carrying capacity of the planet. A number of extrasolar planets have been found so far
be in the habitable zone. Meanwhile, a number of others are known to have
orbit is highly eccentric (elliptical) which result in differences in the amount of heat received
planets and satellites of the parent star.
When the planets and satellites accompanist at the furthest point in the orbit, the amount of heat
received would be less than when they are in the closest point in orbit.
The more elliptical shape of an orbit, the greater the difference in the amount of heat
surface of the planet and the satellite is received while in the nearest and furthest points.
An example is as in planetary systems that are 16 Cygni B
in a binary star system paired with a star 16 Cygni A. Planets orbiting
star 16 Cygni B has a large kelonjongan, worth 0.67.
Star 16 Cygni B as the parent star has a luminosity (the amount of energy
the entire surface of the star is emitted in all directions per second) at 1.4 times
solar luminosity (the luminosity of the Sun = 385 trillion trillion watts). Although the average number of
energy received from the planet's parent star is only a half times Earth's received from
The sun, due to the highly elliptical orbit of the planet which happens to be very large variation, from 20
percent to 260 percent of the amount of energy received by the Earth's surface. Surely this
Similarly to the effect that accompanies the satellites of Jupiter.
Will the natural satellites that accompany the giant gas planets such a time in
the future can be a comfortable place to live? Just as the Earth is necessary
time to provide a comfortable environment for the existence of life, all very
depends on the evolutionary processes that take place there.
If at some later proven to provide a comfortable place for
continuity of life, would human civilization on Earth was quite
long to be able to see it? Or is it the human race has managed to establish
colonies in space like a dream of the late astronomer Carl Sagan? Or
Interstellar travel and discover other habitable areas as
replacement of the Earth has been congested?
Everything is possible, and most importantly the awareness to take care of the Earth
has sustained us for so long.
Sources: Reuters (24 September 2004)
Posted By Febri Irawanto
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