The Planets
Introduction
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The
solar system contains many planets, each of them being unique and having
distinct features.
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In
this presentation, I am going to discuss:
§ The different types of planets.
§ The composition of the planets
§ A brief description of the
composition of ceres.
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Based
on their composition, planets are mainly divided into two types; gas giants and
terrestrial planets.
i)
Gas Giants:
•
Gas
giants are composed of a high percentage of solid material. Due to the extreme
pressure that exists within the core of a gas giant, hydrogen may be converted
into a metallic solid or liquid form. Frequently, there are other materials
interspersed within this solid matrix as well.
•
Although
all gas giants contain high amounts of hydrogen and helium within their overall
composition, they may also contain heavier materials such as methane and
ammonia. The differences in composition can tell us a great deal about the
circumstances under which each planet was formed.
ii)
Terrestrial planets:
•
A
terrestrial planet, telluric planet, or rocky planet is a planet that is
composed primarily of silicate rocks or metals. Within the Solar System, the
terrestrial planets accepted by the IAU are the inner planets closest to the
Sun, i.e. Mercury, Venus, Earth, and Mars
The
composition of planets:
i)
Mercury:
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Mercury
is the second densest planet, after Earth.
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Like
its fellow terrestrial planets, Mercury has a central core, a rocky mantle, and
a solid crust.
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It
has a large metallic core with a radius of about (2,074 kilometers), about 85
percent of the planet's radius. There is evidence that it is partly molten or
liquid.
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Mercury
possesses a thin exosphere made up of atoms blasted off the surface by the
solar wind and striking meteoroids. Mercury's exosphere is composed mostly of
oxygen, sodium, hydrogen, helium, and potassium.
ii)
Venus:
•
Venus
has a thick, toxic atmosphere filled with carbon dioxide and it’s perpetually
shrouded in thick, yellowish clouds of mostly sulfuric acid that trap heat.
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Venus
has crushing air pressure at its surface – more than 90 times that of Earth-like the pressure you'd encounter a mile below the ocean on Earth.
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Venus'
atmosphere consists mainly of carbon dioxide, with clouds of sulfuric acid
droplets. The thick atmosphere traps the Sun's heat, resulting in surface
temperatures higher than 880 degrees Fahrenheit (470 degrees Celsius)
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Venus
is in many ways similar to Earth in its structure. It has an iron core that is
approximately 2,000 miles (3,200 kilometers) in radius.
iii)
Earth:
•
The
inner core is a solid sphere made of iron and nickel metals about 759 miles
(1,221 kilometers) in radius. There the temperature is as high as 9,800 degrees
Fahrenheit (5,400 degrees Celsius). Surrounding the inner core is the outer
core. This layer is about 1,400 miles (2,300 kilometers) thick, made of iron
and nickel fluids
•
Our
planet's rapid rotation and molten nickel-iron core give rise to a magnetic
field, which the solar wind distorts into a teardrop shape in space. (The solar
wind is a stream of charged particles continuously ejected from the Sun.)
•
In
the center of the planet, the temperature may be up to 7,000 K (6,730 °C;
12,140 °F) and the pressure could reach 360 GPa (3.6 million atm).
iv)
Mars:
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Mars
has a dense core at its center between 1,500 to 2,100 kilometers in
radius. It's made of iron, nickel, and sulfur. Surrounding the core is a rocky
mantle between 1,240 to 1,880 kilometers thick, and above that, a crust made of
iron, magnesium, aluminum, calcium, and potassium.
•
At
the surface, we see colors such as brown, gold, and tan. The reason Mars looks
reddish is due to oxidization—or rusting—of iron in the rocks, regolith
(Martian “soil”), and dust of Mars. This dust gets kicked up into the
atmosphere and from a distance makes the planet appear mostly red.
•
The
temperature on Mars can be as high as 70 degrees Fahrenheit (20 degrees Celsius)
or as low as about -225 degrees Fahrenheit (-153 degrees Celsius).
v)
Jupiter:
•
The
composition of Jupiter is very mysterious and unknown to humankind. It is
truly a behemoth, being twice the size of all the other planets combined.
•
The
composition of Jupiter is similar to that of the Sun—mostly hydrogen and
helium. Deep in the atmosphere, pressure and temperature increase, compressing
the hydrogen gas into a liquid. This gives Jupiter the largest ocean in the
solar system—an ocean made of hydrogen instead of water.
•
Scientists
think that, at depths perhaps halfway to the planet's center, the pressure
becomes so great that electrons are squeezed off the hydrogen atoms, making the
liquid electrically conducting like metal.
•
It
is still unclear if deeper down, Jupiter has a central core of solid
material or if it may be a thick, super-hot and dense soup. It could be
up to 90,032 degrees Fahrenheit (50,000 degrees Celsius) down there,
made mostly of iron and silicate minerals (similar to quartz).
•
The
core of Jupiter is surrounded by a layer of metallic hydrogen that extends
outwards to as much as 78% of the radius of the planet. On Earth, metallic
hydrogen has only been produced in a laboratory for about a microsecond, at
pressures of over a million atmospheres (>100 GPa or gigapascals), and
temperatures of thousands of kelvin. In Jupiter, metallic hydrogen is usually
in a liquid form.
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Extra
fact: Jupiter is best known for its colorful storms. But also has some of
the most vivid auroras. Not only are the auroras bigger than Earth, but they
are also hundreds of times more energetic than auroras in our homeworld. And,
unlike those on Earth, they never cease. On Earth, the most intense auroras are
caused by solar storms, but Jupiter generates its own. The strong magnetic
field of the gas giant grabs charged particles from its surroundings, including
particles thrown into space by its orbiting moon Io, known for its numerous and
large volcanoes
vi)
Saturn:
•
Like
Jupiter, Saturn is made mostly of hydrogen and helium. At Saturn's center is a
dense core of metals like iron and nickel surrounded by rocky material and
other compounds solidified by intense pressure and heat. It is enveloped by
liquid metallic hydrogen inside a layer of liquid hydrogen—similar to Jupiter's
core but considerably smaller.
•
Saturn
is the only planet in our solar system whose average density(687 kg/m3)is
less than water. The giant gas planet could float in a bathtub. [ The
density of water=1000 kg/m3].
vii)
Uranus- The ice giant:
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Uranus
is one of two ice giants in the outer solar system (the other is Neptune). Most
(80 percent or more) of the planet's mass is made up of a hot dense fluid of
"icy" materials—water, methane and ammonia—above a small rocky core.
Near the core, it heats up to 9,000 degrees Fahrenheit (4,982 degrees Celsius)
•
It
is the second least dense planet after Saturn(1271 Kg/m3)
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Uranus'
atmosphere is mostly hydrogen and helium, with a small amount of methane and
traces of water and ammonia
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Uranus
gets its blue-green color from methane gas in the atmosphere. Sunlight passes
through the atmosphere and is reflected back out by Uranus' cloud tops. Methane
gas absorbs the red portion of the light, resulting in a blue-green color.
viii) Neptune:
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Neptune
is one of two ice giants in the outer solar system.
•
Most
(80 percent or more) of the planet's mass is made up of a hot dense fluid of
"icy" materials—water, methane, and ammonia—above a small, rocky core.
Of the giant planets, Neptune is the densest.
•
Scientists
think there might be an ocean of super-hot water under Neptune's cold clouds.
It does not boil away because incredibly high pressure keeps it locked inside.
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Neptune
does not have a solid surface. Its atmosphere (made up mostly of hydrogen,
helium and methane) extends to great depths, gradually merging into water and
other melted ices over a heavier, solid core with about the same mass as Earth.
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Neptune's
atmosphere is made up mostly of hydrogen and helium with just a little bit of
methane. Neptune's neighbor Uranus is a blue-green color due to such
atmospheric methane, but Neptune is a more vivid, brighter blue, so there
exists an unknown component that causes the more intense color.
ix)
Ceres:
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Dwarf
planet Ceres is the largest object in the asteroid belt between Mars and
Jupiter and the only dwarf planet located in the inner solar system.
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Called
an asteroid for many years, Ceres is so much bigger and so different from the
rocky neighbors that scientists classified it as a dwarf planet in 2006.
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Ceres
is more similar to the terrestrial planets (Mercury, Venus, Earth and Mars)
than its asteroid neighbors, but it is much less dense.
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Ceres
probably has a solid core and a mantle made of water ice. In fact, Ceres could
be composed of as much as 25 percent water. If that is correct, Ceres has more
water than Earth does. Ceres' crust is rocky and dusty with large salt
deposits. The salts on Ceres are not like table salt (sodium chloride), but
instead are made of different minerals like magnesium sulfate.
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The
lack of craters might be due to layers of ice just below the surface. The
surface features could smooth out over time if ice or another lower-density
material, such as salt, is just below the surface. It is also possible that
past hydrothermal activity, such as ice volcanoes, erased some large craters.
Additional
feature:
This is the
first-ever audio file recorded on the surface of Mars. This recording was made
by the SuperCam instrument on NASA’s Perseverance Mars rover on Feb. 19, 2021,
just about 18 hours after landing on the mission’s first sol or Martian day
Presentation based on the Planets
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