Siteadmin, Check users, Administrators
12,071
edits
Changes
Jump to navigation
Jump to search
New article
In [[astronomy]], an [[apsis]] (plural ''apsides'') is either of the two points in an [[orbit]] at which the orbiting body makes its closest or farthest approach to the primary.<ref>"[http://en.wiktionary.org/wiki/apsis Entry for 'Apsis']." ''[http://en.wiktionary.org/wiki/Wiktionary:Main_Page Wiktionary]. Accessed January 16, 2008.</ref><ref>Dooling, Dave, and Kneale, Ruth A., eds. "[http://www.nso.edu/press/glossary.html#apsis Entry for 'Apsis']," ''Glossary of Terms'', National Solar Observatory, February 21, 2005. Accessed January 16, 2008.</ref>
The point of closest approach is called the ''periapsis'' (from the Greek ''peri'' around).
The point of farthest approach is called the ''apoapsis'' or ''apapsis'' (from the Greek ''apo'' away from).
== Terminology==
Astronomers often change the root word ''apsis'' to a root specific to the primary under discussion. Most of these roots are Greek-derived, although some [[Latin]]-derived roots have occasionally appeared in the technical literature or even on the Internet.
The following table lists the proper roots, including some Latin-derived roots:
{| class="wikitable"
|-
! Primary
! Greek
! Latin
|-
| [[Galaxy]]
| galacticon
|
|-
| [[Star]]
| astron<ref name=elision>When combining the ''apo-'' prefix with the roots ''astron'' and ''helion'', the letter ''o'' is elided.</ref>
|
|-
| [[Black hole]]
| melasma
| nigricon
|-
| [[Sun]]
| helion<ref name=elision/>
|
|-
| [[Mercury (planet)|Mercury]]
| hermion
|
|-
| [[Venus]]
| cytherion<ref>An alternative root ''krition'' (from the Greek ''Kritias'', an older form of Aphrodite, the Greek equivalent of Venus) sometimes appears.</ref>
|
|-
| [[Earth]]
| gee
|
|-
| [[Moon]]
| selene<ref>In [[Project Apollo]] the root ''cynthion'' was in official use. The rationale is that ''cynthion'' was the proper root for an artificial body in orbit around the Moon.</ref>
| lune
|-
| [[Mars]]
| areion
|
|-
| [[Jupiter]]
| zene<ref>This root never appears in the astronomical literature. Astronomers prefer to use ''jove'' or else the generic ''apsis''. The root ''zene'' derives from a more ancient genitive, ''zenos'', of the name ''Zeus''.</ref>
| jove
|-
| [[Saturn]]
| krone
| saturnion
|-
| [[Uranus]]
| uranion
|
|-
| [[Neptune]]
| poseidion
|
|-
| [[Pluto]]
| hadion
|
|}
== References and notes ==
<references/>
[[Category:Astronomy]]
The point of closest approach is called the ''periapsis'' (from the Greek ''peri'' around).
The point of farthest approach is called the ''apoapsis'' or ''apapsis'' (from the Greek ''apo'' away from).
== Terminology==
Astronomers often change the root word ''apsis'' to a root specific to the primary under discussion. Most of these roots are Greek-derived, although some [[Latin]]-derived roots have occasionally appeared in the technical literature or even on the Internet.
The following table lists the proper roots, including some Latin-derived roots:
{| class="wikitable"
|-
! Primary
! Greek
! Latin
|-
| [[Galaxy]]
| galacticon
|
|-
| [[Star]]
| astron<ref name=elision>When combining the ''apo-'' prefix with the roots ''astron'' and ''helion'', the letter ''o'' is elided.</ref>
|
|-
| [[Black hole]]
| melasma
| nigricon
|-
| [[Sun]]
| helion<ref name=elision/>
|
|-
| [[Mercury (planet)|Mercury]]
| hermion
|
|-
| [[Venus]]
| cytherion<ref>An alternative root ''krition'' (from the Greek ''Kritias'', an older form of Aphrodite, the Greek equivalent of Venus) sometimes appears.</ref>
|
|-
| [[Earth]]
| gee
|
|-
| [[Moon]]
| selene<ref>In [[Project Apollo]] the root ''cynthion'' was in official use. The rationale is that ''cynthion'' was the proper root for an artificial body in orbit around the Moon.</ref>
| lune
|-
| [[Mars]]
| areion
|
|-
| [[Jupiter]]
| zene<ref>This root never appears in the astronomical literature. Astronomers prefer to use ''jove'' or else the generic ''apsis''. The root ''zene'' derives from a more ancient genitive, ''zenos'', of the name ''Zeus''.</ref>
| jove
|-
| [[Saturn]]
| krone
| saturnion
|-
| [[Uranus]]
| uranion
|
|-
| [[Neptune]]
| poseidion
|
|-
| [[Pluto]]
| hadion
|
|}
== References and notes ==
<references/>
[[Category:Astronomy]]