My very eyes may just see upon nine planets. My vicious eager mom just served us nine pizzas. Yummy! Can you name the planets in our solar system? We just gave you a couple of hints. How many planets are there? Nine? Wrong, there are eight. The solar system is indeed filled with so much wonders. From terrestrial worlds to gas giants playing hula-hoops to an underdog stripped of its planetary status — there are more about our planetary neighbors than whatever you know of. Dear friends, my very educated mates just saw us now.
Related media: Introduction To The Solar System: Crash Course Astronomy #9
Our Planetary Neighborhood
Our solar system is made up of the sun, eight planets, several moons hosted by these planets, an asteroid belt, wandering chunks of ice debris — of which one is a dwarf planet. The planets are Mercury, Venus, Earth (the one you live on), Mars, Jupiter, Saturn, Uranus, and Neptune. In this article, we’ll give an in depth summary about the planets: their discoveries, distance from the sun, sizes, surface geography, geodesics, moons, and wrap up with some weird mind-blowing facts. Oh! Did we mention Pluto?
This is the first and smallest planet in the solar system, and the closest to the sun, named after the Roman messenger god. The first record of its discovery was in the year 265 Before the Common Era (B.C.E) by the Greek astronomer Timocharis. Its roughly 57 million kilometers (35 million miles), that’s 0.387 Astronomical Units (AU) away from the sun, which takes 88 Earth days to go around the sun, and has 58.6 Earth days in a day. It has a diameter of 4,878 kilometers (3,030 miles) — that’s roughly the size of the continental United States, making it two-fifths the size of Earth.
(Fun fact: all the planets in the solar system are named after Roman gods, except Earth and Uranus, which were named after Greek gods).
Mercury has a surface area of 75 million square kilometers (47 million square miles), mostly covered with several craters due to asteroid impacts. Temperatures on Mercury are hellish, reaching a surface high of 430 degrees Celsius (800 degrees Fahrenheit) during the day, however, and this is eerie, having no atmosphere to retain heat, the surface temperature can drop to -180 degrees Celsius (290 degrees Fahrenheit). What’s even eerie? Despite being the closest to the sun, would you believe there is an ice cap at its pole?
What else do you think we missed about Mercury?
This is the second planet from the sun, and also second brightest object seen in the night sky after the moon. It was named after the Roman goddess of love and beauty (the only planet named after a feminine figure). It was certainly discovered long before Galileo Galilei, but he made accurate observations and even discovered it had phases. Venus is roughly 108 million kilometers (67 million miles), that’s 0.722 AU away from the sun, with an orbital period of 225 Earth days, and has 243 Earth days in a day. It has a diameter of 12,104 kilometers (7,521 miles) — the only planet comparable to Earth in size, but rotates in an opposite direction, retrograde.
The geographic composition of Venus is similar to Earth, having a metallic core, liquid mantle, and rocky crust. It has a surface area of 460 million square kilometers (286 million square kilometers), scattered with active volcanoes like no other. Venus is the hottest planet despite Mercury being the closest to the sun. It has a surface temperature of 471 degrees Celsius (880 degrees Fahrenheit), that’s hot enough to melt lead; with a thick, toxic atmosphere filled with carbon dioxide, with pressures up to 92 bars, making Venus the deadliest planet bar none. What’s eerie? Its atmosphere is so intense that it literally rains sulfuric acid. Yikes!
(Fun fact: surface features on Venus are all named after feminine figures).
What else do you think we missed about Venus?
Welcome to Earth! The third planet from the sun, and the only habitable planet that supports life, because there is PBnJ and liquid water on its surface. How cute! Its 29.2 percent made up of landmasses, majority of it is oceans. Earth is roughly 150 million kilometers (93.2 million miles), that’s exactly 1 AU away from the sun (an AU is the average distance the Earth is from the sun). It was discovered by humans, of course; and let’s assume you know a day, a year, and basically how time works on Earth. However, the planet is about 4.5 billion years old, a little bit younger than the sun, relatively.
Everything here on Earth is classified into one of four major subsystems: i.e. land, water, air, and living things, known as “spheres.” The land is lithosphere, water is hydrosphere, air is (you guessed it) atmosphere, and living things are biosphere. The average surface temperature on Earth is 15 degrees Celsius (59 degrees Fahrenheit), however, it could be extreme. The temperatures ever recorded include 70.7 and -89.2 degrees Celsius (159.2 and -128.5 degrees Fahrenheit) in the Lut Desert in Iran, and Vostok, Antarctica, as the hottest and coldest places, respectively. Least we forget, its the first planet with a moon.
(Fun fact: you’re right now reading this article on this planet).
What else do you think we missed about Earth?
This is the fourth planet, and the second smallest planet after Mercury. Mars was discovered by ancient Romans and named it after their god of war, hence it’s referred to as the “Red Planet.” Its roughly 228 million kilometers (142 million miles), that’s 1.52 AU away from the sun. Mars is quite different from Earth despite our plans of colonizing it someday. It has an orbital period of 687 Earth days, but has 24 hours and 37 minutes in a day, and an axial tilt of 25 degrees — quite close to ours here. However, its pretty small as compared to Earth: a diameter of 6,780 kilometers (4213 miles) wide.
(Fun fact: Mars is the only planet that humans have been able to probe its surface. Looking at you ‘Curiosity’ and ‘InSight’ rovers).
The Red Planet is a cold, dry forbidden desert landscape of mostly sand and rocks. It has a surface geography pretty much as that of Earth, such as volcanoes, canyons, and valleys, to some extent that its believed to have been teeming with oceans. The largest active volcano is on Mars, Olympus Mons; its about 25 kilometers (16 miles) high. No match for Everest. If humans would ever land on Mars, its not a great idea. The atmosphere of Mars is much thinner than ours. There is more than 95 percent of carbon dioxide and less than one percent of oxygen — you’ll certainly not survive that. However, Mars has twin moons: Phobos and Deimos. How cute!
What else do you think we missed about Mars?
This is the fifth planet, and the largest of all the planets in the solar system which is twice more the mass of all the others, combined. Its a gas giant (a planet entirely made of gas) slightly less than 1000th the mass of the sun. It was probably discovered by Galileo; which is roughly 779 million kilometers (484 million miles), that’s 5.20 AU away from the sun. Everything about Jupiter is huge. It takes 12 years for it to make a revolution around the sun, 10 Earth hours (not days) for the sun to rise and set, and covers an area 62 billion square kilometers (24 billion square miles). Now that’s the Big Boss.
Jupiter has no solid surface, however, it has a dense core of heavy elements — a solid core of the collection of rocks and metallic debris that formed together with the planet eons ago. As a gas giant, its atmosphere is mostly hydrogen and helium gas, just like the sun (scientists even think of Jupiter as a failed star). Its planet is covered in a thick mixture of brownish red-yellow clouds, having a massive spot in it. This is actually a hurricane that has lasted for as long as we’ve known Jupiter. The planet has four major moons: Europa, Ganymede, Io, and Callisto — known as the Galilean moons, named after (you guessed it) Galileo — and there are even several more.
(Fun fact: Jupiter’s moons can be seen with the naked eye, only if you have incredibly good night vision. Galileo saw them first).
What else do you think we missed about Jupiter?
This is the sixth planet, the second largest, and bar none, the most beautiful of all the others in the solar system. It was first discovered by Galileo in 1610, but Dutch astronomer Christiaan Huygens discovered it has rings. Its roughly 1.43 billion kilometers (889 million miles), that’s 9.58 AU away from the sun. It has an orbital period of 29 Earth years, and 11 Earth hours a day. Its also a gas giant with a diameter of 116,464 kilometers (72,367 miles) wide, 95 times massive than Earth, however, its one-eighth the average density of Earth. So, if you have a very big pool, Saturn will float. Indeed, its a gem in the solar system.
(Fun fact: There are five planets in the solar system you can see with your naked eyes — these are Mercury, Venus, Mars, Jupiter, Saturn, excluding Earth).
Looking at it’s ring system, its actually made up of several scattered clumps of ice debris, about ten meters (11 yards) thick, and several kilometers wide. It has a surface area of 43 billion square kilometers (17 billion square miles), a thick gassy atmosphere made up of mostly hydrogen, with less amounts of helium, and some traces of ammonia and methane, too. However, temperatures on Saturn vary depending on altitude; ranging from -173 degrees Celsius (-280 degrees Fahrenheit), and -113 degrees Celsius (-170 degrees Fahrenheit). Saturn also wins the moon title: having moons like Titan, Enceladus, Hyperion, Mimas, Iapetus, Dione, and how big enough an ice debris is to be called moon.
What else do you think we missed about Saturn?
This is the seventh planet, and third gas giant in the solar system, which was named after the Greek god of the sky. It was discovered by German astronomer William Herschel in 1781. Its roughly 2.88 billion kilometers (1.79 billion miles), that’s 19.2 AU away from the sun, with an orbital period of 84 Earth years, and makes 18 Earth hours a day. It has the third largest diameter: that’s 50,724 kilometers (31,518 miles) wide, and covering a surface area of 8.1 billion square kilometers (3.13 billion square miles). Awkwardly, its the only planet that’s tilted on its axis — almost 98 degrees, making it look like its rotating on its side. Uranus has rings, too.
(Fun fact: Jupiter, Uranus, and Neptune all have rings, but to a lesser degree).
Uranus is made up of a molten rocky core, mostly of icy materials like water, ammonia, and methane. This makes up about 20 percent of the planet’s mass. However, it has a thick atmosphere of mostly hydrogen and helium gas, with slight traces of water, ammonia, methane. This also makes up 80 percent of the planet. The methane is what makes Uranus appear blue. On average, surface temperature on Uranus is a frigid -195 degrees Celsius (-320 degrees Fahrenheit), with wind speeds ranging from 145 kilometers per hour (90 miles per hour) to 579 kilometers per hour (360 miles per hour). Uranus has several moons like Miranda, Titania, Umbriel, Oberon, Ariel, Desdemona, Puck, and others.
What else do you think we missed about Uranus?
This is the eighth and farthest of the planets in the solar system, but not the least. It was named after the Roman god of ocean, long before its discovery by several mathematicians, becoming the only planet discovered via math. Its roughly 4.5 billion kilometers (2.8 billion miles), that’s 30.1 AU away from the sun, and an orbital period of a whopping 165 Earth years (since WWII, it hasn’t completed its revolution around the sun), 16 Earth hours a day, and a diameter of 49,244 kilometers (30,599 miles) wide. It has a surface area of 7.6 billion square kilometers (2.9 billion square miles). Neptune is also the coolest planet, literally.
(Fun fact: surface gravity on Neptune is similar to that on Earth).
Its the fourth gas giant with an atmosphere made up of similar components like its neighbors. The planet has a more vivid shade of blue than its previous neighbor Neptune — an indication there is an unknown component that causes that color. Its core is likely made up of iron, nickel, and silicates, with an interior temperature reaching 7,000 degrees Celsius (12,632 degrees Fahrenheit), quite comparable to the sun. It also has the highest pressure of any planet, 7 millibars (700 gigapascals) — that’s twice as high as the Earth’s core. Its believed that it could be raining diamonds on Neptune. Like seriously! It has several moons including Triton, Hippocamp, Despina, Proteus, Galatea, Thelassa, and more.
What else do you think we missed about Neptune?
Lastly, Pluto the underdog. The former planet is now a dwarf icy body wandering in the Kuiper belt — a debris of bodies beyond the orbit of Neptune; being the first and largest object, it was declared a planet in 1930, and named after the Roman god of the underworld. Its roughly 5.91 billion kilometers (3.67 billion miles), that’s 39.5 AU away from the sun, having an orbital period of 248 Earth years, and 153 Earth hours (6.4 Earth days) a day, that’s the longest of all the planets. It has a diameter of 2,376.6 kilometers (1,476.7 miles) wide, with a 57-degree tilt in its axis, its also having a retrograde rotation just like Venus.
(Fun fact: Pluto was named by an 11-year-old girl, Venetia Burney of Oxford in the United Kingdom).
Pluto is made up of a mixture of 70 percent rock and 30 percent water ice, having a rocky core surrounded by a mantle of probably water ice, traces of methane, carbon monoxide (that’s the exhaust from cars), and nitrogen coating its surface. On average, the surface temperature on Pluto is -232 degrees Celsius (-387 degrees Fahrenheit), the coldest of any planet. It has several moons, including Charon, Kerberos, Nix, Hydra, Styx, and thousands of orbiting Kuiper belt debris. In August 2006, the International Astronomical Union (IAU), officially declared Pluto as a dwarf planet, not a planet anymore. Why on Earth did astronomers strip Pluto of its planetary status?
What else do you think we missed about Pluto?
What else do you think we missed about any of these planets? Let us know.
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Written by: Nana Kwadwo, Mon, Oct 11, 2021.