Planetary mnemonic

A visual mnemonic using the left hand to represent the terrestrial planets with the dwarf planet Ceres (/asteroid belt) and the right hand, palm turned upward, to represent the gas giants with the dwarf planet Pluto (along with other TNOs).

A planetary mnemonic refers to a phrase used 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 fingers spread and thumbs in the same direction, with the fingers of one hand representing the terrestrial planets, and the other hand the gas giants. The first thumb represents the Sun and asteroid belt, including Ceres, and the second thumb represents the asteroid belt and trans-Neptunian objects, including Pluto.

Nine planets

An English-language mnemonic which was current in the 1950s was "Men Very Easily Make Jugs Serve Useful Needs, Perhaps" (for Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto). The structure of this sentence suggests that it may have originated before Pluto's discovery, and can easily be trimmed back to reflect Pluto's demotion. Another common English-language mnemonic for many years was "My Very Educated Mother Just Served Us Nine Pizzas". Other mnemonics include "My Very Energetic Mother Jumps Skateboards Under Nana's Patio" and "Mary's violet eyes make Johnny stay up nights plenty",^[1] as well as the apt "My Very Easy Method Just Shows Us Nine Planets", "My Very Efficient Memory Just Stores Up Nine Planets" and "My Very Easy Method Just Speeds Up Naming Planets". Another variant which may predate Pluto's discovery is "Mary's violet eyes make Johnny stay up nights, pondering" and it, too, can be trimmed back. Yet another is "Many Volcanoes Emit Mulberry Jam Sandwiches Under Normal Pressure". However, many of these mnemonics were made obsolete by the 2006 definition of planet, which reclassified Pluto (as well as Ceres and Eris) as a dwarf planet.

Eight planets

When Pluto was demoted to a 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".^[2] In August 2006, for the eight planets recognized under the new definition,^[3] 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.^[4] It also appeared in Indiana University's IU News Room Star Trak on August 30, 2006.^[5] This mnemonic is used by the IAU on their website for the public.^[6] Others angry at the IAU's decision to "demote" Pluto composed sarcastic mnemonics in protest. Schott's Miscellany by Ben Schott included the mnemonic, Many Very Educated Men Justify Stealing Unique Ninth.^[7] Mike Brown, who discovered Eris, mentioned hearing Many Very Educated Men Just Screwed Up Nature.^[8] One particular 9 planet mnemonic, "My very easy memory jingle seems useful naming planets", was easily changed once the demotion occurred, becoming the 8 planet mnemonic, "My very easy memory jingle seems useless now". A slightly risque version is "Mary's 'Virgin' Explanation Made Joseph Suspect Upstairs Neighbor".^[9]

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.^[10] 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).^[11]

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!"^[12]

Longer mnemonics will be required in the future, if more of the possible dwarf planets are recognised 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 200 dwarf planets.)

References

The Solar System
The Sun Mercury Venus Earth Mars Ceres Jupiter Saturn Uranus Neptune Pluto Haumea Makemake Eris
Planets Terrestrial planets Mercury Venus Earth Mars Giant planets Jupiter Saturn Uranus Neptune Dwarf planets Ceres Pluto Haumea Makemake Eris Rings Jovian Saturnian (Rhean) Charikloan Chironean Uranian Neptunian Moons 1 Terrestrial (Moon) Other near-Earth objects 2 Martian Phobos Deimos 67 Jovian Ganymede Callisto Io Europa all 62 Saturnian Titan Rhea Iapetus Dione Tethys Enceladus Mimas Hyperion Phoebe all 27 Uranian Titania Oberon Umbriel Ariel Miranda all 14 Neptunian Triton Proteus Nereid all 5 Plutonian Charon Nix Hydra Kerberos Styx 2 Haumean Hiʻiaka Namaka 1 Makemakean (S/2015 (136472) 1) 1 Eridian (Dysnomia) Lists Solar System objects By size By discovery date Minor planets Gravitationally rounded objects Possible dwarf planets Natural satellites Comets Small Solar System bodies Meteoroids Minor planets moons Comets Damocloids Mercury-crossers Venus-crossers Venus trojans Near-Earth objects Earth-crossers Earth trojans Mars-crossers Mars trojans Asteroid belt Asteroids first discovered: Ceres Pallas Juno Vesta Families Notable asteroids Kirkwood gap Main-belt comets Jupiter trojans Jupiter-crossers Centaurs Saturn-crossers Uranus trojans Uranus-crossers Neptune trojans Cis-Neptunian objects Trans-Neptunian objects Neptune-crossers Plutoids Kuiper belt Plutinos Cubewanos Scattered disc Detached objects Sednoids Hills cloud Oort cloud Hypothetical objects Vulcan Vulcanoids Phaeton Planet V Theia Fifth giant Planets beyond Neptune Tyche Nemesis Planet Nine Exploration (outline) Discovery Astronomy Timeline Spaceflight Robotic spacecraft Human spaceflight Colonization List of probes Timeline Mercury Venus Moon Mars Ceres Asteroids Mining Comets Jupiter Saturn Uranus Neptune Pluto Deep space
Outline of the Solar System Portals Solar System Astronomy Earth sciences Mars Jupiter Uranus Cosmology Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Virgo Supercluster → Laniakea Supercluster → Observable universe → Universe Each arrow (→) may be read as "within" or "part of".