The 9 planets in our solar system and their order from the sun are commonly asked questions in Geography classes. It is an area of interest in planetology (the study of planets). Scientists have tried and are trying to know more about planets and the possibility of humans living in any of them.
The questions: “Names of the 9 planets in order from the sun” or “How many planets are there in our solar system“ have been the most frequent questions asked by my Geography teacher when I was in secondary school. This question has come up several times during quizzes and my geography examinations and would be discussed in detail here to help students understand better.
You will learn the names of these nine (9) planets in order from the sun. However, it should be mentioned that while it is commonly accepted that there are nine planets, some people believe that there are 8 planets in our solar system excluding Pluto which was considered to be the farthest planet discovered lately by scientists and is also classified as a Dwarf planet or Plutoid.
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History of the 9 Planets in our solar system
The ancient Greeks came across seven lights in the sky that moved against the background pattern of stars: the sun, the moon, Mercury, Venus, Mars, Jupiter, and Saturn. then they decided to name them Planetes, or Wanderers. If you observe closely their list, you will notice that the Earth is not included because it appeared as mere pinpricks of light. The Earth was not considered as a planet but as the center or foundation of the universe.
Nicolaus Copernicus convince astronomers to believe that the Sun rather than Earth lies at the center, they however accepted and redefined planets as objects orbiting the sun, thereby putting Earth on the list and removing the sun and moon.
William Herschel an English astronomer then proposed naming them asteroids. In 1851, the number of asteroids had increased to 15, and it was not good enough to consider all the light in the solar system to be planets. Astronomers then decided to list asteroids by their order of discovery rather than by distance from the sun, as for planets, the de facto acceptance of the asteroids as members of a distinct population.
If we still consider asteroids as planets, the majority of schoolchildren studying the solar system would now have to deal with more than 135,000 planets.
Pluto on the other hand, which is the last planet, has a similar issue to the Earth. When Clyde Tombaugh discovered it in 1930, astronomers accepted Pluto as the long-sought Planet X whose gravity would account for unexplained peculiarities in the orbit of Neptune. Pluto was found to be smaller not only than the other eight planets but also as seven of their satellites including Earth and Moon.
Other discoveries showed the characteristics in Neptune’s orbit to be misleading or delusional. For six decades, Pluto was unique and different from other planets at the outer edge of the planetary system. Just as Ceres began to make sense only when it was included as one of the vast population of asteroids, Pluto only appeared in the picture when astronomers found out it was one of a vast population of Kuiper belt objects (KBOs). Astronomers began to consider that it should be included among other planets. This is why Pluto is considered today as the Ninth planet in our solar system.
According to history, revoking the planetary status of Pluto would not be known. The ranks of ex-planets include the sun, moon, and asteroids. However, many people have argued for continuing to call Pluto a planet, because almost everyone has grown quite accustomed to thinking of it as one of the planets.
What is a planet?
Planets are celestial bodies that revolve around the sun as a result of the gravitational force. They have no light of their own. All of them rotate around the sun to reflect the light and heat from it.
The term planet has evolved over its history, from the divine lights of antiquity to the earthly objects of the scientific age. The concept has expanded to include worlds not only in the Solar System but also in hundreds of other extrasolar systems. The ambiguities inherent in defining planets have led to many scientific arguments.
Our solar system consists of the sun, moon, and nine planets. The sun is at the center of the solar system and all other planets revolve around it in their elliptical orbits.
They do not twinkle in the sky. The moon, asteroids, comets, and meteoroids are all parts of the solar system. While the moon orbits around planets; the comets, asteroids, and meteoroids orbit around the sun. These luminaries are called planets.
List of the 9 Planets in order from the sun
Mnemonics on how to remember the nine planets in order from the Sun
Here are two simple Mnemonics for Remembering the names of the 9 Planets in order from the sun.
- “My Very Excellent Mother Just Sent Us Nine Pizzas” or
- “My Very Easy Method Just Simplifies Us Naming Planets”
The first letter of each of these words represents a planet while the position of each word represents the order of the planet relative to the sun.
- My = Mercury
- Very = Venus
- Excellent = Earth
- Mother = Mars
- Just = Jupiter
- Sent = Saturn
- Us = Uranus
- Nine = Neptune
- Pizza = Pluto
The distance between one planet and another will vary depending on where each planet is in its orbit around the sun. These distances could be closer or farther away. This is because all the planets have elliptical orbits that are not perfect circles.
Description of each planet and its order from the Sun
The Sun
This is the largest yellow star in the solar system closest to the Earth. It has a surface temperature of over 6000 0C with an interior temperature of 20,000,000 0C. The sun is much hotter than any of the nine planets and it is the most important part of the solar system. It gives warmth and produces visible light for all living things to produce and function accordingly.
The earth would have been totally dark without the sun. However, without solar radiation from the sun called insolation, all forms of life on the earth’s surface would not have been possible. When it comes to size, the sun is 300,000 times as big as the Earth and 10 times bigger than Jupiter, the largest planet. The sun is often called the heated star.
Stars
The stars, which appear singly when viewed from the earth, actually exist in groups or clusters which are better referred to as Galaxies or Nebulas. Some stars are hotter than the sun, while some are cooler. There are larger stars than the sun while others are smaller. They are very far away from Earth when you view them and they appear like tiny points of light. With the exception of the Sun, Mercury, Venus, and Pluto; all other planets have attendant bodies referred to as Satellites. The sun is the only body in the solar system that shines with its own light while other bodies reflect the light of the sun.
Facts and Characteristics of each of the Nine Planets in order from the Sun
Mercury
This is the 1st, smallest, and hottest planet in the solar system. It is the nearest to the sun having an average distance of 58 km and the diameter is 4,850 km. Its temperature could rise to 800 0F (430 0C) during the day, and it can become as cold as -280 0F (175 0C) during the night.
It takes 88 days for mercury to rotate around the sun once, which makes it a year for Mercury. However, it takes 58 days, 17 hours for mercury to revolve around its own axis. Mercury is very close to the sun, this is why it has a very high temperature. Because of its proximity to the sun, metals like zinc or lead dissolve into vapor at such temperatures.
Mercury has no satellite of its own, no atmosphere, no cloud, rain, wind, or water and hence life is non-existent on this planet. It has innumerable hills and plain land, cliffs, and valleys just like Earth and the surface of Mercury is covered with craters.
Venus
It is the second closest planet to the sun and the closest to the earth. Venus contains no living things because it is the hottest in the solar system. However, it is similar to Earth in terms of size, weight, and density, hence it is termed the Earth’s twin. Venus planet has no satellite of its own but glows in the sky like a star which makes the majority of people refer to it as a star.
Venus is hidden under a dense cloud. The dense cloud in Venus contains sulphuric acid. Naturally, the sun is never visible from the surface of Venus, and its distance from the sun is 108,208,930 km. There is little difference in light between day and night on Venus. Rainfall is usually acid rain.
The diameter of Venus is 12,104 km and it takes 225 days to revolve around the sun. Venus rotates on its axis in a prolonged manner. The sun rises twice and sets twice in the sky of Venus. Based on the picture taken by the American spacecraft, Venus is an arid planet with mountains, valleys, and volcanoes.
Venus Planet
Earth
The Earth is the third closest planet to the sun but not as hot as Venus. It has an average distance of 150, 800,000 km from the sun. Its diameter is nearly 12,667 km. The earth takes 23 hours 56 minutes and 4 seconds to rotate on its own axis and takes 365 days 5 hours 48 minutes 47 seconds to revolve around the sun once. Therefore, one year is equivalent to 365 days.
Being the single natural satellite of the earth, the moon revolves around the earth once every 27days. However, the distance of the Earth from the moon is 384,629 km. The earth is the only planet in whose atmosphere there is the existence of required oxygen, nitrogen, carbon dioxide, and temperature that is necessary for the survival of humans, plants, and animals. Hence, the earth is considered the most important planet in the solar system.
Mars
Planet Mars is the 4th planet in order from the sun. Mars planet looks reddish since the rocks are rusty when they get in contact with oxygen. This planet has two satellites, which are Phobos and Deimos. The diameter of Mars is about 6,787 km, which is half of the earth; and the average distance of this planet from the sun is 228,000,000 km and 142 million miles (229 million kilometers) from the earth.
The day and night on Mars are nearly the same as that of the earth in respect of a period of time. Mars takes 687 days to revolve around the sun which represents a Martian year. The planet takes 24 hours and 37 minutes to rotate on its own axis.
There are gorges volcanoes, mountains, canyons, and craters on the surface of Mars with a little amount of oxygen, a high quantity of carbon dioxide, and no liquid water which makes it impossible for life to exist. Mars is a hard rocky planet that contains Iron oxide (rust), hence it is called the red planet.
Jupiter
It is the fifth and largest planet in the solar system and it is called the king of the planets because of its size. Jupiter has a diameter of 142,984 km when measured at the equator. This planet is larger than the earth about 1,300 times in terms of area and its mass is twice as much as any other planet in the solar system.
The surface temperature of its atmosphere is very low but in the interior, it is quite high, with an average temperature of 125 0C. This Planet is 772,800,000 km away from the sun. The atmosphere around Jupiter is characterized by a violent thunderstorm stronger than what we experience here on earth.
Jupiter takes 11.9 years to revolve around the sun but it takes 9 hours 53 minutes to rotate on its own axis. The atmosphere is made of two gases, hydrogen, and helium. The sun rises twice and sets twice on this planet. Scientists have now discovered 16 satellites on Jupiter with Lo, Uropa, Ganimed, and Callisto being the major satellites; however, scientists believe that there may be the core of ice and rocks about the size of the Earth in the very center of Jupiter.
Saturn
This is the 6th and second largest planet after Jupiter. The sun is 1,417,600,000 km away from Saturn. It is actually a huge gaseous globe with a diameter of 120,000 km. The size of Saturn is 760 times greater than planet Earth. Saturn takes 29 years and 5 months to revolve around the sun once but rotates on its own axis in 10 hours 40 minutes.
There are thousands of rings with different colors surrounding Saturn. It has 22 natural satellites outside its ring with Titan, Hua, Dion, Capitus, and Tethris being the major rings. The surface of Saturn remains covered by ice. The atmosphere contains hydrogen, a mixture of helium, methane, and ammonia gas.
Uranus
Uranus is the third largest and the seventh planet in order of distance from the sun. It covers a distance of 2,870,972,170 km from the sun. Uranus takes about 84 years to complete a single rotation around the sun, but it takes only 10 hours 49 minutes to rotate on its own axis. Its diameter is 31,764 miles (51,119 km) and covered with a blue-green cloud, due to the methane gas in the atmosphere above them.
The temperature at the top of the cloud is -3700F (-2200C), the atmosphere contains a high percentage of frozen methane and it has an average temperature of 1700C. Recently, scientists have discovered some rings around this planet, but these rings are not bright. Uranus has 5 natural (five) satellites such as Mirinda, Ariel, Ambriel, Titania, and Oberon. However, scientists believe there could be some core of ice and rocks at the very center of Uranus. Read more on Uranus planet here.
Neptune
This is the 8th planet in order from the sun with a distance from the sun being 4,468,800 km away. The planet is cold, has a dark spot when viewed afar, it is surrounded by a blue cloud. Neptune has an area is equivalent to 72 Earths and 17 earth’s in mass. Its Diameter is 48,400km. The atmosphere is made of a mixture of gases, mainly frozen methane, ammonia, and other gases. The temperature on Neptune above the cloud is -3550F (-2150C).
Neptune has two natural satellites such as Triton and Neroid. It usually takes 164.8 years for Neptune to revolve around the sun. Recently, two rings have been discovered to exist around Neptune.
Pluto
The Pluto is considered the 9th planet in order from the sun. In order words, it is the farthest planet from the sun. Most times, its orbit crosses the orbit of Neptune and when this happens, Neptune becomes the farthest planet from the sun. Pluto has a surface temperature of -370 0F (-220 0C). It is the coldest planet in the solar system and also has a thin surface of frozen methane and if possible some Nitrogen as well.
Pluto takes about 247.7 years to go round the sun. The distance of Pluto from the sun is 5,850,000 km. Scientists believe that the planet could contain water, ice, methane ice, and rocks. Pluto is the only planet in our solar system that has not been visited by spacecraft as it is only viewed with radar from afar off, therefore, very little is known about it. Learn more about Pluto here