Astronomy 101

THREE: VENUS: EVENING STAR, GOD OF LOVE

Venus, Oh Venus! Easily the brightest planet in the sky and by far the most beautiful thing to see at sunset/sunrise. Venus isn’t the god of love and beauty for no reason, it’s bright and shiny appearance truly makes it look beautiful. However, Venus is a perfect example of hell (GASP).

Now before we start off with molten lead and the smell of hydrogen sulfide and supervolcanoes, it’s important to know more about the better aspects of the planet. Venus has been called the “Earth’s Twin” many times in the past, it is roughly the same size and looks roughly similar. Also, it is imperative that you know about Venus transits (Although you might not see one (in your entire life)). Just like the moon coming between the Earth and the Sun, Venus comes between the Earth and the sun at times. This is known as a Venus transit, but, given Venus’s colossal distant from Earth, it doesn’t affect the Sun’s luminosity by much, however, transits are a great way of learning about distances in the solar system. Venus transits occur in pairs separated by eight years, those pairs are separated by almost a century, the last pair of Venus transits were in 2004 and 2012, the next is in 2117 and 2125.

I stated previously that Venus is nicknamed as the Earth’s twin, well, if it is a twin, it’s the Evil one. Venus looks bright and shiny because of a thick atmosphere surrounding it which reflects almost all of the Sun’s light. Venus is closer to the Sun than the Earth so you might expect it to be hotter, well, what you didn’t see coming was Venus’s surface temperature, a staggering 450 degrees Celsius, hotter than Mercury. Its atmosphere is composed primarily of carbon dioxide (97% CO2), Earth only has a CO2 percentage of 0.04%, yet a phenomenal effect called climate change/global warming is still impacting our little, blue dot, imagine living in a planet with around twenty-five hundred times the CO2 level on Earth. Also, it rains pure sulfuric acid on Venus, but, its so hot that the drops evaporate before hitting the ground. Venus has A LOT of volcanoes, and its entire surface is covered in craters. Also, its believed that Venus may be so hot that instead of a mantle, core and such, it may have pure, bubbling, dangerous, fiery, explosive, hot, lethal, volatile magma.

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It is believed that Venus, at one point of time, may have supported life during a phase of the Solar System when the Sun was younger and cooler, however, as the Sun grew old, the heat Venus received increased exponentially, its oceans evaporated and the water immense amounts of water vapour in the atmosphere acted as greenhouse gases. This trapped more heat, which resulted in the carbon dioxide dissolved in water evaporating as well, along with Carbon Dioxide on solid surface, this further increased the greenhouse effect and accounts for Venus’s current day hellish situation. Scientists call this a Runaway Greenhouse Effect. All of this reduced Venus’s magnetic field to null, solar flares and interstellar wind then stripped Venus’s atmosphere of lighter gases such as water vapour and such, leaving sulfur dioxide and carbon dioxide as the main components. New scientific theories that have recently started emerging have stated that life may exist in the clouds of Venus, which is not far from reality. Venus’s clouds have a steady, livable temperature in which microbes could develop. Scientific Date recorded by reflecting light ofF Venus’s clouds did reveal fluctuations, which may be due to the presence of organic compunds.


TWO: MERCURY: SWIFT MOVER, MESSENGER OF THE GODS

Mercury is the closest planet to the sun in the solar system (I expect you to know that). Now before getting started off with distances and such, it is important to know about the astronomical unit, which is the distance between the Sun and the earth, 150 million kilometres. Mercury’s perihelion (Point of orbit closest to the sun) stands at 0.31 AU and its aphelion (Point of orbit farthest from the sun) stands at 0.47 AU.  Another important factor in astronomy is eccentricity, that is, the elliptical-ness of an orbit. An eccentricity of 0 means the orbit is a perfect circle, an eccentricity of 1 means that the orbit is perfectly elliptical. Mercury has an eccentricity of about 0.21 (Earth has an eccentricity has an eccentricity of about 0.0167). That sky-rocketing eccentricity results in rapid temperature changes on Mercury, it’s near twice as hot at its perihelion than at its aphelion. Mercury is weird, it’s day lasts as long as approximately 59 earth days and its year consists of 88 days. Mercury’s orbit is really weird, due to the immense tidal forces that it feels being very close to the sun, it takes the sun 2 mercury years, 176 days to cross the sky once. In fact, Mercury is very weird. If you stood on the surface of Mercury at its aphelion, the planet’s spin is faster than the orbit speed, so the sun moves westwards rapidly but when it reaches its perihelion, the orbit speed is faster than the sun, thus, the sun stops in the sky and starts moving backwards (WEIRD), then, as the forces from the sun weaken, the spin again exceeds the orbital speed and the sun starts moving westwards again.

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Till date, two probes have been sent to Mercury, Mariner 10 and Messenger. Mariner 10 made 3 flybys and mapped 45% of the surface, Messenger made a series of close flybys then went into orbit around the planet in 2011. Since then, much has been revealed about Mercury, such as the fact that it has no atmosphere (No surprises there) and is heavily cratered.

Mercury is almost as dense as the Earth, but it has a higher core volume: total volume ratio than Earth. Some suggest that this might be due to a colossal collision a long time ago which blew off the upper layers, another theory is that the young sun vapourised the upper layers.


ONE:THE SUN: CENTER OF THE SOLAR SYSTEM, SUSTAINER OF LIFE ON EARTH.

What is the sun? A dense ball of fire which hosts nuclear fusion, A main sequence star destined to expand to a red giant in a few millennia and perhaps the only harbinger of life in the entire universe. All of these titles can be granted to the sun easily, but for us humans, it is much more. The sun consists primarily of hydrogen gas, it’s around 1.4 million kilometres across, big enough to contain around, well, this might be uncomfortable, a million Earths, A MILLION EARTHS! A MILLLIOOOOONNNNN EAAARRRTHHHHS!!! How heavy is it, well, once again, be prepared to be surprised, it weights around two octillion tonnes, that’s 2 with 27 zeroes after it, to get a fair measure, that’s a billion times a billion times a billion. More monumental numbers to follow, the pressure at the inner core of the sun is 270 billion times atmospheric pressure, that is, the pressure being exerted on you by the surrounding air right now and the temperature is around 15 million degrees Celsius, that’s hot enough to make an omelette easily. How does the sun function? It fuses hydrogen into helium at its core, releasing A LOT of heat energy. The hydrogen is stripped of its electrons, leaving only protons behind. Nuclear fusion follows, converting that ultra-dense sub-atomic substance into helium at phenomenally high temperatures. Every second, the sun converts 700 million tonnes of hydrogen into 695 million tonnes of helium, the remaining 5 million tonnes are transformed into energy, in fact, this much energy is equivalent to detonating 400 billion one-megaton nuclear bombs every second. Now after you manage to process these colossal figures, think about how far away the sun is, 150 million kilometres, so far away that light takes 8 minutes to get here from the surface of the sun, now get this, it releases so much energy that you can feel it so far away, so FAR AWAY, SO MUCH ENERGY, AAARGGGHHH, My brain’s processor just went bust. Now prepared to be mentally boggled up again, every time hydrogen fuses into helium at the core of the sun, light energy is produced, it smashes into sub-atomic particles which absorb it, then re-emit the light energy with a slightly less energy value, this process repeats for millions of kilometres until the light reaches the surface and is free to travel outwards, towards the Earth and beyond. Accounting for the sun’s size, this process takes about 200,000 years, give or take 50,000 years. Now get this, the light you see right now coming from the sun started out from nuclear fusion around the time when Homo Sapiens got their start, GET THAT.

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Loops of plasma in the sun, thousands of times bigger than the Earth generate magnetic fields around them, sometimes, these magnetic fields reach the surface of the sun and get blocked out from beneath, resulting in them darkening, these are called sunspots. Sometimes, these magnetic fields can become tangled up, blasting huge amounts of solar debris and ‘sun’ particles into space in events known as solar flares and CMEs. The atmosphere of the Earth filters away the harmful light and the magnetic field deflects those highly harmful subatomic particles but some very few are funnelled down through the poles, resulting in the southern and northern lights. Sometimes, just sometimes, enough particles enter the Earth to cause power shortages and grid failures, resulting in widespread devastation. In 1859, the most massive solar storm ever recorded hit Erath, scientists estimate that if a storm of the same scale hit Earth today, satellites would fry off, communications would die and essentially, mankind’s legs will be cut off from beneath it, the internet and technology will cease to exist with no electricity, mankind would take at least a decade to recover.

As we progress with astronomy 101, you will realize that the Sun’s destructive potential and energy capacity is dwarfed throughout the universe by blue giants, supernovae and black holes. In fact, similar to the Earth being nothing in comparison with the sun, the sun is nothing in comparison with a blue giant, as the following quote exhibits.

“Our sun is just a star in someone else’s night sky” – Michael