This article is the written script of an episode from our podcast series: Kandelaa – Conversations.
( Bu yazı, podcast serimiz Kandelaa – Conversations’tan alınan bir bölümün yazılı metnidir. )
Planet; the name comes from the Greek word: planētēs, in other words, wanderer. That is in fact quite understandable; those heavenly bodies revolve around maybe not idly, but neatly. Space is a massive core to explore, and we can start with our Solar System and the wanderers in it.
Sun
First and foremost, our Sun isn’t a planet but a star. Being the largest celestial body in the Solar System, the Sun comprises 99.86% of the whole system’s mass. Once upon a time, which is billions of years ago, hydrogens compressed and fused to form helium in its atmosphere of extreme temperatures and pressure. These two elements contribute to the composition of the Sun.
How hot is it? Well, tremendously much – 15 million degrees Celsius. Comprehensively, nothing can live on it.
Most importantly, our star anchors the planets in order by its gravity, and every mass, not only planets, spins around it.
Mercury
The littlest of all! The dwarf-like planet (not a dwarf planet) Mercury is the closest one to the Sun without any moons, in other words, natural satellites orbiting around it. The condition on Mercury is undoubtedly harsh: The temperature reaches 430 degrees Celsius, but right oppositely, since it has no atmosphere, the heat cannot be preserved, and the nighttime temperature plummets to minus 180 degrees.
If not an atmosphere, we can mention an exosphere instead. Mercury is exposed to the solar wind and particles (meteoroids) scattering from the Sun by which the atoms blast off its surface.
Venus
Being quite similar to the Earth, just like a sister, Venus relatively has a close size, mass index, and density to its. Nevertheless, it is not a suitable biotope for organisms to dwell in, and we can’t really speak of anything alive on it. This is mainly because of its extreme temperature and the atmospheric pressure that is ninety times that of the Earth. Mercury might have been thought to be the hottest planet in the solar system; however, possibly due to the impact of the green gases in its atmosphere, Venus is in the first place regards to it.
Besides, no water source was detected on Venus’ surface so far; the planet is incredibly dry and futile for life as we know.
Interestingly, we can’t speak of a magnetic field as in the Earth for Venus, so its atmosphere – since there’s no magnetic attraction – must have been already exhausted. Though, as we said earlier, Venus does have an atmosphere, which heats it to ultrahigh temperatures; the depletion is probably compensated by the volcanos lying across the planet. After an eruption, various gases, carbon dioxide, and sulfur diffuse into the air in the shape of dense clouds, making Venus’ atmosphere highly toxic.
Earth
The Earth is the only planet where life and geological activities, such as tectonic movement, exist as we know. Different layers of the Earth have important features: first of all, it has a unique layer that is called the “hydrosphere” and is made up of water we know. This one provides an enormous likelihood and convenience to inhabit organisms.
Apart from it, the atmosphere has several sublayers and only the lowest layer-troposphere- contains 75% of the whole air within the atmosphere. The major part of the air-70%- comprises nitrogen, and the rest contains oxygen of 21% and other gases like helium. Additionally, most of the ozone, a layer that drains the ultraviolet radiation coming from the sun to prevent detrimental impacts and sustain the life quality, is found in the next layer – the stratosphere.
Meteoroids wander around idly in space until they get attracted by a gravitational field. This is potentially hazardous, mainly the life on the Earth would be threatened continuously if something doesn’t hamper them. Luckily, the planetary magnetosphere shields the surface from solar and cosmic radiation, limiting atmospheric stripping and maintaining habitability. (Wikipedia)
Mars
There is found no proof that Mars has inhabited life so far, but we learn more about this neighboring planet each day. Water on Mars’s surface may have led organisms to live; however, the conditions are not sufficient to support life. The pressure is capable to create weather, and findings support that it once, 3-4 billion years ago, was geologically more active than now. Though, Mars’ atmosphere is mostly of carbon dioxide. Tiny but mighty, Mars has two moons (natural satellites), which are possibly meteoroids or ejected debris.
By the by, the crimson color that we see is based on the iron-oxide compounds within the planet.
Jupiter
We now pass onto the gas giants; this group is known for their enormous masses that they can even hold helium and hydrogen – the two lightest gases.
As the name befits, Jupiter is the largest planet in the Solar System, with a size of more than 1000 times the Earth. The planet constitutes most of the remaining mass in the system when that of the sun is subtracted.
Jupiter is made up of hydrogen for the most part, but the atmosphere contains the gases like ammonia, sulfur, methane, and water vapor (Don’t get deceived! It doesn’t have a solid surface to have liquid water.)
Jupiter basically has a ring, but unlike Saturn’s, it is made of dust rather than ice or rock so it’s quite faint that we don’t always notice.
Naturally, thanks to a gigantic mass and a strong gravitational field, in turn, there are 80 satellites of Jupiter
Saturn
The most interesting thing about Saturn is probably the ring around it. This ring system is made of ice and rock in different sizes. Saturn possesses some similar features to those of Jupiter: they are both gas giants, and they have many moons and rings in different forms, but not solid surfaces.
Even though the Saturn days are shorter than the Earth days, by 10.7 hours, it takes 29 Earth years for Saturn to complete its orbit around the Sun.
There are 53 moons confirmed to be turning around Saturn. Moreover, one of those satellites named Titan is larger than Mercury and the only satellite in the Solar System that has a dense atmosphere.
Trivia: Saturn is less dense than water.
Uranus
Known for the coldest atmosphere in the Solar System, and also a ring system of 13 different ringlets. Uranus is an icy planet; the basic compounds of its mass are water, ammonia, and methane. The temperature can drop to -223,3 degrees Celsius. Other than that, Uranus is tilted towards the right with 98 degrees angle, so its poles point toward and away from the Sun. This is probably caused by a collision with at least one celestial body in Uranus’ history. But due to this position, the magnetic field around Uranus is unstable and also tilted.
Unlike the other planets, Uranus orbits around the Sun on its side, and it takes a total of 84 Earth years to complete this spin.
Uranus is also the name father of the radioactive element “Uranium”. The new finding was named a few years after its discovery. Uranus has 27 satellites.
Neptune
Another icy planet, Neptune has tremendous winds blowing at 1931 km/h speed- they even break the sound barrier! Named after the Roman god of seas, Neptune consists of the ice oceans of water, ammonia, and methane. Methane is the compound that gives the blue color to Neptune as it does to Uranus.
There are a bunch of things associated with “seas and oceans” when Neptune is the subject. 14 moons that spin around it are named after the sea gods and nymphs in Greek mythology (NASA). But remember, the particles are solid (icy) rather than in a fluid form.
These are the planets within our system. Still, there are some arguments about whether some dwarf planets fulfill the planetary criteria and can be accepted as one. After the discovery of other dwarf planets beyond Pluto, the scientists of IAU felt an urge to create new conditions for calling a celestial body a planet.
Because otherwise, there might have been a lot to add to the Solar System if the dwarf planets were also “planets”. Pluto and certain others do meet the criteria, but the list was not further expanded to reduce the number to a memorable level, implies Dr. Alan Stern, a planetary scientist and the leader of NASA’s New Horizon mission. (Forbes)