Planetary mnemonic

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A representation of the above method with the left hand representing the terrestrial planets and the right hand, with palm turned upward, is representing the gas giants along with TNOs Solar System Hand Mnemonic.png
A representation of the above method with the left hand representing the terrestrial planets and the right hand, with palm turned upward, is representing the gas giants along with TNOs

A planetary mnemonic refers to a phrase created to remember the planets and dwarf planets of the Solar System, with the order of words corresponding to increasing sidereal periods of the bodies. One simple visual mnemonic is to hold out both hands side-by-side with thumbs in the same direction (typically left-hand facing palm down, and right-hand palm up). The fingers of hand with palm down represent the terrestrial planets where the left pinkie represents Mercury and its thumb represents the asteroid belt, including Ceres. The other hand represents the gas giants, with its thumb representing trans-Neptunian objects, including Pluto.

Contents

Nine planets

Before 2006, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto were considered as planets. Below are partial list of these mnemonics:

With the IAU's 2006 definition of planet which reclassified Pluto as a dwarf planet, along with Ceres and Eris, these mnemonics became obsolete.

Eight planets

When Pluto's significance was changed to dwarf planet, mnemonics could no longer include the final "P". The first notable suggestion came from Kyle Sullivan of Lumberton, Mississippi, USA, whose mnemonic was published in the Jan. 2007 issue of Astronomy magazine: "My Violent Evil Monster Just Scared Us Nuts". [4] In August 2006, for the eight planets recognized under the new definition, [5] Phyllis Lugger, professor of astronomy at Indiana University suggested the following modification to the common mnemonic for the nine planets: "My Very Educated Mother Just Served Us Nachos". She proposed this mnemonic to Owen Gingerich, Chair of the International Astronomical Union (IAU) Planet Definition Committee and published the mnemonic in the American Astronomical Society Committee on the Status of Women in Astronomy Bulletin Board on August 25, 2006. [6] It also appeared in Indiana University's IU News Room Star Trak on August 30, 2006. [7] This mnemonic is used by the IAU on their website for the public. [8]

Others angry at the IAU's decision to "demote" Pluto composed sarcastic mnemonics in protest:

Eleven planets and dwarf planets

In 2007, the National Geographic Society sponsored a contest for a new mnemonic of MVEMCJSUNPE, incorporating the then-eleven known planets and dwarf planets, including Eris, Ceres, and the newly demoted Pluto. On February 22, 2008, "My Very Exciting Magic Carpet Just Sailed Under Nine Palace Elephants", coined by 10-year-old Maryn Smith of Great Falls, Montana, was announced as the winner. [12] The phrase was featured in the song 11 Planets by Grammy-nominated singer and songwriter Lisa Loeb and in the book 11 Planets: A New View of the Solar System by David Aguilar ( ISBN   978-1426302367). [13]

Thirteen planets and dwarf planets

Since the National Geographic competition, two additional bodies were designated as dwarf planets, Makemake and Haumea, on July 11 and September 17, 2008 respectively. A 2015 New York Times article suggested some mnemonics including, "My Very Educated Mother Cannot Just Serve Us Nine Pizzas—Hundreds May Eat!" [14]

Longer mnemonics will be required in the future, if more of the possible dwarf planets are recognized as such by the IAU. However, at some point enthusiasm for new mnemonics will wane as the number of dwarf planets exceeds the number that people will want to learn (it is estimated that there may be up to 200 dwarf planets). [15]

See also

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The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. The largest of these objects are the eight planets, which in order from the Sun are four terrestrial planets ; two gas giants ; and two ice giants. The Solar System developed 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.

<span class="mw-page-title-main">Pluto</span> Dwarf planet

Pluto is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume, by a small margin, but is less massive than Eris. Like other Kuiper belt objects, Pluto is made primarily of ice and rock and is much smaller than the inner planets. Pluto has only one sixth the mass of Earth's moon, and one third its volume.

<span class="mw-page-title-main">90377 Sedna</span> Dwarf planet

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Michael E. Brown is an American astronomer, who has been professor of planetary astronomy at the California Institute of Technology (Caltech) since 2003. His team has discovered many trans-Neptunian objects (TNOs), including the dwarf planet Eris, which was originally thought to be bigger than Pluto, triggering a debate on the definition of a planet.

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<span class="mw-page-title-main">Dwarf planet</span> Small planetary-mass object

A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be gravitationally rounded, but insufficient to achieve orbital dominance like the eight classical planets of the Solar System. The prototypical dwarf planet is Pluto, which for decades was regarded as a planet before the "dwarf" concept was adopted in 2006.

IAU definition of <i>planet</i> 2006 International Astronomical Union definition

The International Astronomical Union (IAU) defined in August 2006 that, in the Solar System, a planet is a celestial body that:

  1. is in orbit around the Sun,
  2. has sufficient mass to assume hydrostatic equilibrium, and
  3. has "cleared the neighbourhood" around its orbit.
<span class="mw-page-title-main">Eris (dwarf planet)</span> Dwarf planet beyond Pluto in the Solar System

Eris is the most massive and second-largest known dwarf planet in the Solar System. It is a trans-Neptunian object (TNO) in the scattered disk and has a high-eccentricity orbit. Eris was discovered in January 2005 by a Palomar Observatory–based team led by Mike Brown and verified later that year. In September 2006, it was named after the Greco–Roman goddess of strife and discord. Eris is the ninth-most massive known object orbiting the Sun and the sixteenth-most massive overall in the Solar System. It is also the largest known object in the solar system that has not been visited by a spacecraft. Eris has been measured at 2,326 ± 12 kilometers (1,445 ± 7 mi) in diameter; its mass is 0.28% that of the Earth and 27% greater than that of Pluto, although Pluto is slightly larger by volume. Both Eris and Pluto have a surface area that is comparable to the area of Russia or South America.

<span class="mw-page-title-main">Small Solar System body</span> Object in the Solar System

A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first defined in 2006 by the International Astronomical Union (IAU) as follows: "All other objects, except satellites, orbiting the Sun shall be referred to collectively as 'Small Solar System Bodies' ".

In astronomy, planetary mass is a measure of the mass of a planet-like astronomical object. Within the Solar System, planets are usually measured in the astronomical system of units, where the unit of mass is the solar mass (M☉), the mass of the Sun. In the study of extrasolar planets, the unit of measure is typically the mass of Jupiter (MJ) for large gas giant planets, and the mass of Earth (ME) for smaller rocky terrestrial planets.

<span class="mw-page-title-main">Gonzalo Tancredi</span> Uruguayan astronomer (born 1963)

Gonzalo Tancredi is an Uruguayan astronomer and full professor in the Department of Astronomy at the University of the Republic in Montevideo, Uruguay. He is an active member of the International Astronomical Union (IAU) and investigator at Los Molinos Observatory.

The International Union of Geological Sciences (IUGS) is the internationally recognized body charged with fostering agreement on nomenclature and classification across geoscientific disciplines. However, they have yet to create a formal definition of the term "planet". As a result, there are various geophysical definitions in use among professional geophysicists, planetary scientists, and other professionals in the geosciences. Many professionals opt to use one of several of these geophysical definitions instead of the definition voted on by the International Astronomical Union, which is the governing body that astronomers recognize when it comes to nomenclature.

References

  1. ↑ "My Very Elegant Mother Just Sat Upon Nine Porcupines". www.rocemabra.com. Retrieved 2019-10-10.
  2. ↑ Beatty, Kelly (2008-02-28). "Of Planets and Palace Elephants". SkyandTelescope.com. Archived from the original on 2013-02-02. Retrieved 2008-09-16.
  3. ↑ Garfoot, Ash (May 2000). "Ash Garfoot (May 2000)". www.facebook.com. Retrieved 2020-09-25.
  4. ↑ "Physics 110 Astronomy Mnemonics". www.csub.edu/Physics. Archived from the original on 2012-01-18.
  5. ↑ "International Astronomical Union, iau0603 -- Press Release, IAU 2006 General Assembly: Result of the IAU Resolution votes, 24 August 2006" . Retrieved 2016-01-30.
  6. ↑ "American Astronomical Society Committee on the Status of Women in Astronomy Bulletin Board, August 25, 2006". Archived from the original on 2016-05-07. Retrieved 2016-01-30.
  7. ↑ "Indiana University, IU News Room, Star Trak, August 30, 2006" . Retrieved 2016-01-30.
  8. ↑ "Pluto and the Developing Landscape of Our Solar System, Questions and Answers". International Astronomical Union, IAU for the Public. Retrieved 2016-01-30.
  9. ↑ Schott, Ben (2008). Schott's Miscellany 2009. New York: Bloomsbury USA. p. 77. ISBN   978-1-59691-382-0.
  10. ↑ "Julia Sweeney and Michael E. Brown". Armand Hammer. 2007. Archived from the original on 2008-10-06. Retrieved 2009-12-14.
  11. ↑ "XKCD Presents: Some New Science Mnemonics".
  12. ↑ "National Geographic Children's Books Announces Winner of New Planetary Mnemonic". Archived from the original on March 6, 2008. Retrieved 2008-02-29.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  13. ↑ "Planet Song". National Geographic. Archived from the original on February 24, 2012. Retrieved September 23, 2008.
  14. ↑ "My Very Educated Readers, Please Write Us a New Planet Mnemonic". The New York Times. January 20, 2015. Retrieved June 20, 2015.
  15. ↑ "Our Solar System has 127 probable planets and 500+ possibles | NextBigFuture.com". 2018-09-08. Retrieved 2023-02-15.
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