The Number of Planets in the Solar System
Prepared by the Research Committee of IslamToday.net under the supervision of Sheikh `Abd al-Wahhâb al-Turayrî|
In the Qur’ân, Joseph relates a dream to his father wherein he sees eleven planets, the Sun, and the Moon all prostrating themselves to him. Some Muslims have recently suggested taking this as evidence that our Solar System has eleven planets. This is especially the case after the recent discovery of Eris, and (as a consequence of that discovery) the International Astronomical Union re-designating planetary bodies in the Solar System so that it officially recognizes eight planets and three dwarf planets.
In this article, we will be discussing the claim that the Qur’ân suggests the existence of eleven planets in our Solar System.
Discussing the Verse
Allah says: “
When Joseph said to his father: ‘O my father! I have seen eleven planets and the Sun and Moon. I have seen them prostrate themselves to me.’ Said (the father): ‘My small son! Do not relate your dream to your brothers, lest they concoct a plan against you, for Satan is to man an avowed enemy.” [Sûrah Yûsuf: 4-5]
This was a dream that Prophet Joseph (peace be upon him) had when he was a boy. The eleven planets represented his brothers. This is why Joseph’s father Jacob (peace be upon him), who understood the meaning of the dream, warned Joseph not to relate the dream to his brothers.
Indeed, the Qur’ân tells us the meaning of the dream in a later verse of the same chapter that depicts an event that took place much later in Joseph’s life. Allah says: “And he raised his parents high on the throne and they fell down in prostration before him. He said: ‘O my father! This is the fulfillment of my vision of old! Allah has made it come true!” [Sûrah Yûsuf: 100]
Ibn Kathîr writes:
In Joseph’s dream the eleven stars represent his brothers, who were eleven, and the Sun and the Moon represent his father and mother. This explanation was given by Ibn `Abbâs, al-Dahhâk, Qatâdah, Sufyân al-Thawrî and `Abd al-Rahmân b. Zayd b. Aslam. Joseph’s vision became a reality forty years later – or as some say, eighty years – when Yusuf raised his parents to the throne while his brothers were before him.
This is what the dream represented. It was in no way detailing a point of astronomy.
Moreover, even if we were to assume that the eleven planets that Joseph (peace be upon him) saw in his dream were the images of real heavenly bodies, Joseph mentions them in an absolute, unqualified sense. There is nothing in the verse to indicate that those eleven are the only planets in existence, or that those planets refer specifically to objects within our Solar System, or even that they refer to planets as astronomers define them today.
We must also realize that at the time the Qur’ân was reveled, the Arabic word used in the verse – kawkab – was used to refer to stars as well as to what we consider planets. Restricting the word kawkab to mean planets as opposed to stars was a much later development. In the dictionary al-Qamûs al-Muhît (131), al-Fayrûzabâdî defines a kawkab as a “star” (najm), and indeed the word kawkab was traditionally used interchangeably with najm.
Therefore, we can safely conclude that the verse is not at all addressing the question of how many planets are in the Solar System. The verse is simply referring to Joseph’s dream vision where his brothers appear as celestial bodies. Islam has no doctrinal stance on the matter.
The Number of Planets in the Solar System is a Question of Terminology
In the field of Astronomy, the number of planets in the Solar System is primarily a question of nomenclature. It depends on two things:
(1) What we observe in space and the discoveries that we make
(2) How we wish to define a planet.
In ancient times, people defined planets as: any celestial object that travels in a regularly repeating path through the Earth’s night sky. Indeed, in ancient Greek, the word planet means “wanderer”. Based on this definition, the ancients counted seven planets: the Sun, the Moon, Mercury, Venus, Mars, Jupiter, and Saturn.
This definition suited the level of astronomical knowledge that the ancients had and also was in harmony with the idea that the Earth was the center of the universe, because a planet could just as easily be defined as “any object in orbit around the Earth”.
When the heliocentric (Sun-centered) model was adopted, astronomers felt that they needed to revise the definition of a planet. The name planet was retained, but it was redefined to mean: “any object in a regular orbit around the Sun”. Consequently, the Sun and Moon were no longer counted as planets. Earth was counted as a planet instead. This led to a total of six planets: Mercury, Venus, Earth, Mars, Jupiter, and Saturn.
When Uranus was discovered in 1781, the number of planets increased to seven. When Neptune was discovered in 1846, the number again increased to eight. These increases were the result of new discoveries, and not of a change in definition.
The definition of a planet as “any object in a regular orbit around the Sun” remained in force until the mid-1800s. Therefore, when the small object Ceres was discovered between Mars and Jupiter in the year 1801, it was considered a planet, which brought the total to nine. When more small objects (known as 2 Pallas, 3 Juno and 4 Vesta) were discovered in similar orbits, they brought the grand total of objects defined as planets to twelve. The twelve planets remained standard in astronomy books until the mid-1800s.
As more small bodies were discovered between Mars and Jupiter, astronomers became dissatisfied with referring to the members of this swarm of objects as planets. Instead, they reclassified all of these objects as asteroids in an “Asteroid Belt”, reducing the number of objects recognized as planets back down to eight.
Then, in 1930, Pluto was discovered beyond the orbit of Neptune, bringing the total of planets up to nine. This remained the case for the remainder of the twentieth century, throughout which schoolchildren all learned about the “nine planets”.
Certain discoveries were made that challenged Pluto’s status as a planet. For one thing, astronomers realized that Pluto is much smaller than originally assumed. It is smaller, in fact, than our Moon. However, this alone was not enough to challenge its status as a planet. Though Pluto is smaller than Earth’s Moon, it is still much larger than the largest asteroid, Ceres.
Then, starting in the late 20th century, other objects comparable in size to Pluto (but all at least somewhat smaller) were discovered beyond the orbit of Neptune. Astronomers recognized that there exists a belt of such objects, and referred to it as the Kuiper Belt. None of these new objects were regarded as planets, but as “Kuiper Belt objects”. Some astronomers began to argue that Pluto should not be classified as a planet either, but should rather be regarded as the largest known Kuiper Belt object.
This let to heated debates among astronomers as to whether Pluto should be considered a planet, and consequently whether there were eight or nine known planets in the Solar System. The debate came to a head in 2005 when Eris, an object larger and more distant than Pluto, was discovered.
The International Astronomical Union decided it was high time to come up with a precise definition of a planet. A number of proposed definitions were debated, and on August 24, 2006, the following resolutions were adopted:
1. A planet of our Solar System was redefined to mean a celestial body that
(a) is in orbit around the Sun
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (a nearly round) shape
(c) has cleared the neighborhood around its orbit
This definition disqualifies Pluto as a planet, since Pluto shares its orbital region with a number of similar objects.
2. A new term, dwarf planet, was adopted for objects like Pluto. A dwarf planet is defined as a celestial body that:
(a) is in orbit around the Sun
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (a nearly round) shape
(c) has not cleared the neighborhood around its orbit
This definition applies to a number of round objects orbiting beyond Neptune as well as to Ceres, the largest object in the Asteroid Belt. However, at present the International Astronomical Union has only officially classified three objects as dwarf planets: Ceres, Pluto, and Eris. Nevertheless, many other known objects are expected to be classified as dwarf planets in the near future.
Consequently, there are at present eight known planets according to the new definition. They are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Also, there are a large number of known dwarf planets, three of which have already been officially declared as such and many others which are awaiting classification. Among the objects that are expected to be officially classified as dwarf planets in the near future are: Orcus, Quaoar, Sedna, Varuna, 2003 EL61, 2005 FY9, Ixion, and possibly Charon.
Therefore, the present grand total of eleven (planets + dwarf planets together) is only temporary, since the official classification of other known dwarf planets is simply a matter of procedure. Also, astronomers expect to discover many other large, round objects beyond Neptune’s orbit, since such discoveries have been considerable in recent years.
Conclusions
This shows us quite clearly how dangerous it is to try and interpret verses of the Qur’ân to express meanings that those verses do not express. Unfortunately, some people today have the habit of advancing such interpretations in hopes of establishing the existence of certain scientific facts or recent theories in the Qur’ân.
As we have seen, the number of planets in our Solar System is not only the result of discoveries, but is also a consequence of changing definitions of what a planet is. As other planets are discovered, the number of planets changes. Also, we have seen that whenever we have learned something new about the composition of our Solar System, astronomers have felt the need to revise the very definition of a planet.
Therefore, there is as yet no absolute and final answer regarding the number of planets in our solar system, since the very definition of a planet is something imprecise. There are many different types of celestial bodies in our solar system so that, regardless of what definition scientists might adopt, there will always be borderline cases that challenge our attempts at classification. Allah has created a universe of wondrous variety.
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