Fifth planet (hypothetical)
Encyclopedia
In the history of astronomy
, a handful of solar system bodies have been counted as the fifth planet from the Sun
. Under the present definition of a planet
, this celestial body
is Jupiter
.
became the sixth planet with the discovery of Ceres in 1801. Soon, three more asteroids, Pallas
(1802), Juno
(1804), and Vesta
(1807) were discovered. They were counted as separate planets, despite the fact that they shared an orbit as defined by the Titius-Bode law
. Between 1845 and 1851, eleven additional asteroids were discovered and Jupiter had become the twentieth planet. At this point, astronomers began to classify asteroids as minor planets. Following the reclassification of the asteroids in their own group, Jupiter became the fifth planet once again. With the redefinition of the term planet in 2006, Ceres is now considered a dwarf planet
.
and Jupiter
has long been thought to have occupied the space where the asteroid belt
is currently located. Scientists in the 18th century dubbed this hypothetical planet Phaeton
. Today the Phaeton hypothesis, superseded by the accretion model, has been discarded by the scientific community; however, some fringe scientists
regard this theory as credible and even likely.
episode of the Hadean
era. Chambers and Lissauer also claim this Planet V most probably ended up crashing into the Sun. Unlike the Disruption Theory's fifth planet, "Planet V" is not credited with creating the asteroid belt.
History of astronomy
Astronomy is the oldest of the natural sciences, dating back to antiquity, with its origins in the religious, mythological, and astrological practices of pre-history: vestiges of these are still found in astrology, a discipline long interwoven with public and governmental astronomy, and not...
, a handful of solar system bodies have been counted as the fifth planet from the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. Under the present definition of a planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
, this celestial body
Celestial Body
Celestial Body is a Croatian film directed by Lukas Nola. It was released in 2000....
is Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
.
Previous fifth planets
There are three main ideas regarding hypothetical planets between Mars and Jupiter.Asteroids
During the early 19th century, as asteroids were discovered, they were considered planets. JupiterJupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
became the sixth planet with the discovery of Ceres in 1801. Soon, three more asteroids, Pallas
2 Pallas
Pallas, formally designated 2 Pallas, is the second asteroid to have been discovered , and one of the largest. It is estimated to constitute 7% of the mass of the asteroid belt, and its diameter of 530–565 km is comparable to, or slightly larger than, that of 4 Vesta. It is however 20%...
(1802), Juno
3 Juno
Juno , formal designation 3 Juno in the Minor Planet Center catalogue system, was the third asteroid to be discovered and is one of the larger main-belt asteroids, being one of the two largest stony asteroids, along with 15 Eunomia. Juno is estimated to contain 1% of the total mass of the asteroid...
(1804), and Vesta
4 Vesta
Vesta, formally designated 4 Vesta, is one of the largest asteroids, with a mean diameter of about . It was discovered by Heinrich Wilhelm Olbers on March 29, 1807, and is named after the Roman virgin goddess of home and hearth, Vesta....
(1807) were discovered. They were counted as separate planets, despite the fact that they shared an orbit as defined by the Titius-Bode law
Titius-Bode law
The Titius–Bode law is a hypothesis that the bodies in some orbital systems, including the Sun's, orbit at semi-major axes in a function of planetary sequence...
. Between 1845 and 1851, eleven additional asteroids were discovered and Jupiter had become the twentieth planet. At this point, astronomers began to classify asteroids as minor planets. Following the reclassification of the asteroids in their own group, Jupiter became the fifth planet once again. With the redefinition of the term planet in 2006, Ceres is now considered a dwarf planet
Dwarf planet
A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be spherical as a result of its own gravity but has not cleared its neighboring region of planetesimals and is not a satellite...
.
The Disruption Theory
A hypothetical planet between MarsMars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
and Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
has long been thought to have occupied the space where the asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
is currently located. Scientists in the 18th century dubbed this hypothetical planet Phaeton
Phaeton (hypothetical planet)
Phaeton is the name of a hypothetical planet posited to once have existed between the orbits of Mars and Jupiter whose destruction supposedly led to the formation of the asteroid belt...
. Today the Phaeton hypothesis, superseded by the accretion model, has been discarded by the scientific community; however, some fringe scientists
Fringe science
Fringe science is scientific inquiry in an established field of study that departs significantly from mainstream or orthodox theories, and is classified in the "fringes" of a credible mainstream academic discipline....
regard this theory as credible and even likely.
The Planet V Theory
Based on simulations, NASA space scientists John Chambers and Jack Lissauer have proposed the existence of a planet between Mars and the asteroid belt, going in a successively eccentric and unstable orbit, 4 billion years ago. They connect this planet, which they name Planet V, and its disappearance with the Late Heavy BombardmentLate Heavy Bombardment
The Late Heavy Bombardment is a period of time approximately 4.1 to 3.8 billion years ago during which a large number of impact craters are believed to have formed on the Moon, and by inference on Earth, Mercury, Venus, and Mars as well...
episode of the Hadean
Hadean
The Hadean is the geologic eon before the Archean. It started with the formation of the Earth about 4.7 Ga and ended roughly 3.8 Ga, though the latter date varies according to different sources. The name "Hadean" derives from Hades, Greek for "Underworld", referring to the "hellish"...
era. Chambers and Lissauer also claim this Planet V most probably ended up crashing into the Sun. Unlike the Disruption Theory's fifth planet, "Planet V" is not credited with creating the asteroid belt.
Fifth planet in fiction
The concept of a fifth planet which had been destroyed to make the asteroid belt, as in the Disruption Theory, has been a popular one in fiction.See also
- First planet (disambiguation)
- Second planet (disambiguation)
- Third planet (disambiguation)
- Fourth planet (disambiguation)
- Fifth planet (disambiguation)
- Sixth planet (disambiguation)Sixth planet (disambiguation)Sixth planet refers to:*Saturn, the sixth planet from the Sun*Jupiter, the sixth planet from the Earth in the Ptolemaic geocentric cosmology-See also:*First planet *Second planet *Third planet...
- Seventh planet (disambiguation)
- Eighth planet (disambiguation)
- Ninth planet (disambiguation)
- Tenth planet (disambiguation)
- Eleventh planetEleventh planetEleventh planet may refer to:*Vesta, the eleventh object to be named a planet, later to be reclassified as an asteroid.*Uranus, the eleventh planet from the Sun upon Vesta's discovery, though this was quickly superseded by new discoveries.*Eris, which would be the eleventh planet if the...
- Twelfth planet (disambiguation)Twelfth planet (disambiguation)The 12th Planet is a book by Zecharia Sitchin.Twelfth planet may also refer to:*12th Planet , a Los Angeles based dubstep producer and DJ.*Nibiru , the pseudoscientific planet described in Sitchin's book...
- Planets beyond NeptunePlanets beyond NeptuneFollowing the discovery of the planet Neptune in 1846, there was considerable speculation that another planet might exist beyond its orbit. The search began in the mid-19th century but culminated at the start of the 20th with Percival Lowell's quest for Planet X...
- Trans-Neptunian objectTrans-Neptunian objectA trans-Neptunian object is any minor planet in the Solar System that orbits the Sun at a greater distance on average than Neptune.The first trans-Neptunian object to be discovered was Pluto in 1930...
- Trans-Neptunian objects in fictionTrans-Neptunian objects in fictionThe region of the Solar System beyond Neptune contains sparse populations of small icy objects. These include the Kuiper belt, with its well-known member Pluto, and other plutoids including Haumea and Makemake...
- List of solar system bodies formerly considered planets
- Hypothetical planetary object