Glossary term: Perihelion
Description: Most objects in the Solar System have elliptical orbits, with the Sun at one of the foci. Perihelion is the point along the orbit where the orbiting body is closest to the Sun. Mathematically, this point marks one end of the major axis of the ellipse. In this word "peri" denotes closest point and "helion" denotes the Sun. Accordingly, this word may only be used when the central body is the Sun. When the central body is a star that is not the Sun the term is "periastron"; when the central body being orbited is the Earth the term is "perigee". The general term regardless of the central body is "periapsis".
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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher
The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".
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In Other Languages
- Arabic: الحضيض الشمسي
- German: Perihel
- French: Périhélie
- Italian: Perielio
- Japanese: 近日点 (external link)
- Korean: 근일점
- Simplified Chinese: 近日点
- Traditional Chinese: 近日點
Related Media
Halley's Comet
Caption: Halley’s Comet, is a well-known periodic comet, named after the English astronomer Edmond Halley. It has an orbital period of approximately 75 years and is visible from Earth with the naked eye when it passes through the inner solar system.
The image shows Halley’s Comet, officially designated 1P/Halley, with a tail of gas and dust streaming away from the Sun. It was taken from the La-Silla-Observatory in Chile in 1986 during Halley's Comet's last visit to the inner solar system. The stars in this image appear elongated or as lines of three different colored dots as image was created from three separate observations in different colors of light and the telescope was tracking the comet, which was moving very slightly compared to the background stars. Note that the comets tail does not point in exactly the same direction as the elongation of the stars. This shows us that the comet tail is not always behind the comet, but instead pointing away from the Sun.
The comet passes its perihelion (closest distance to the Sun) at a distance of around 0.59 astronomical units, right between the orbits of Mercury and Venus. Beyond Neptune, it reaches its aphelion (furthest distance from the Sun) at a distance of approximately 35 astronomical units. Halley's Comet reached aphelion in December 2023 and is now moving inwards again. It is expected to be seen with the naked eye from Earth again in mid-2061.
Credit: ESO
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