## Apsis |

An **apsis** (**apsides** * apse*.

- For a body orbiting the
Sun , the point of least distance is the(perihelion n /), and the point of greatest distance is the(aphelion n /).^{[2]} - The terms become
**periastron**and**apastron**when discussing orbits around other stars. - For any satellite of
Earth , including theMoon , the point of least distance is the**perigee**(iː /) and greatest distance the**apogee**. - For objects in
lunar orbit , the point of least distance is sometimes called the**pericynthion**(n /) and the greatest distance the**apocynthion**(n /).**Perilune**and**apolune**are also used.^{[3]} - For an orbit around any
barycenter , the terms**periapsis**and**apoapsis**(or**apapsis**) are used.**Pericenter**and**apocenter**are equivalent alternatives.

A straight line connecting the periapsis and apoapsis is the *line of apsides*. This is the

Historically, in

In

- mathematical formulae
- terminology
- perihelion and aphelion
- see also
- references
- external links

These

- Pericenter
- Maximum speed, , at minimum (pericenter) distance, .
- Apocenter
- Minimum speed, , at maximum (apocenter) distance, .

While, in accordance with

where:

*a*is thesemi-major axis :*μ*is thestandard gravitational parameter *e*is theeccentricity , defined as

Note that for conversion from heights above the surface to distances between an orbit and its primary, the radius of the central body has to be added, and conversely.

The *a*. The *b*.

The geometric mean of the two limiting speeds is

which is the speed of a body in a circular orbit whose radius is .

Other Languages

Afrikaans: Apside

Alemannisch: Apsis (Astronomie)

العربية: قبا

asturianu: Ápside

বাংলা: অপদূরবিন্দু

беларуская: Апацэнтр і перыцэнтр

беларуская (тарашкевіца): Пэрыцэнтар і апацэнтар

भोजपुरी: एप्सिस

български: Апсида (астрономия)

català: Àpside

čeština: Apsida (astronomie)

dansk: Apsis (astronomi)

Deutsch: Apsis (Astronomie)

eesti: Apsiid (astronoomia)

español: Ápside

Esperanto: Apsido

euskara: Apside

فارسی: اوج و حضیض

français: Apside

galego: Apse

한국어: 장축단

հայերեն: Ապոկենտրոն և պերիկենտրոն

हिन्दी: मन्द

hrvatski: Apsida (astronomija)

Ido: Apsido (astronomio)

Bahasa Indonesia: Apsis

íslenska: Nándarstaða og firðstaða

italiano: Apside

עברית: אפסיד

ქართული: აპოცენტრი და პერიცენტრი

қазақша: Апоцентр және перицентр

Latina: Apsis

latviešu: Apsīda

lietuvių: Apsidė (astronomija)

magyar: Apszispont

македонски: Апсида (астрономија)

മലയാളം: അപസൗരം

मराठी: उपनाभी बिंदू

Bahasa Melayu: Apsis

Nederlands: Apofocus en perifocus

日本語: 近点・遠点

norsk: Apsis (astronomi)

norsk nynorsk: Apsis i astronomi

Plattdüütsch: Apsis (Astronomie)

polski: Apsyda (astronomia)

português: Apside

română: Apsidă

русский: Апоцентр и перицентр

Scots: Apsis

සිංහල: දුරාන්තිකය

Simple English: Apsis

slovenčina: Apsida (astronómia)

slovenščina: Apsidna točka

srpskohrvatski / српскохрватски: Apsida (astronomija)

suomi: Apsidi (tähtitiede)

svenska: Apsis

தமிழ்: சுற்றுப்பாதை வீச்சு

ไทย: จุดปลายระยะทางวงโคจร

Türkçe: Apsis

тыва дыл: Апогей

українська: Апсиди

Tiếng Việt: Củng điểm quỹ đạo

中文: 拱點