Heliocentric orbit
Encyclopedia
A heliocentric orbit is an orbit
around the Sun
. All planet
s, comet
s, and asteroid
s in our Solar System
are in such orbits, as are many artificial probes
and pieces of debris
. The moons of planets in the Solar System, by contrast, are not in heliocentric orbits as they orbit their respective planet. An interior heliocentric orbit is an orbit inside the orbit of the Earth, for example the orbit of Venus
. An exterior heliocentric orbit is an orbit outside the orbit of the Earth, for example the orbit of Mars
.
While it is convenient to think of orbits around the Sun, bodies in the Solar System do not actually orbit the Sun. Instead, all bodies in the Solar System (including the Sun) actually orbit the barycenter of the Solar System. A similar phenomenon allows the detection of extrasolar planets by way of the radial velocity method.
The helio- prefix is derived from the ancient Greek
word helios, meaning "sun", and also Helios
, the personification of the Sun in Greek mythology
.
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
around the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. All planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
s, comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s, and asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
s in our Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
are in such orbits, as are many artificial probes
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
and pieces of debris
Space debris
Space debris, also known as orbital debris, space junk, and space waste, is the collection of objects in orbit around Earth that were created by humans but no longer serve any useful purpose. These objects consist of everything from spent rocket stages and defunct satellites to erosion, explosion...
. The moons of planets in the Solar System, by contrast, are not in heliocentric orbits as they orbit their respective planet. An interior heliocentric orbit is an orbit inside the orbit of the Earth, for example the orbit of Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
. An exterior heliocentric orbit is an orbit outside the orbit of the Earth, for example the orbit of Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
.
While it is convenient to think of orbits around the Sun, bodies in the Solar System do not actually orbit the Sun. Instead, all bodies in the Solar System (including the Sun) actually orbit the barycenter of the Solar System. A similar phenomenon allows the detection of extrasolar planets by way of the radial velocity method.
The helio- prefix is derived from the ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
word helios, meaning "sun", and also Helios
Helios
Helios was the personification of the Sun in Greek mythology. Homer often calls him simply Titan or Hyperion, while Hesiod and the Homeric Hymn separate him as a son of the Titans Hyperion and Theia or Euryphaessa and brother of the goddesses Selene, the moon, and Eos, the dawn...
, the personification of the Sun in Greek mythology
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
.
See also
- HeliocentrismHeliocentrismHeliocentrism, or heliocentricism, is the astronomical model in which the Earth and planets revolve around a stationary Sun at the center of the universe. The word comes from the Greek . Historically, heliocentrism was opposed to geocentrism, which placed the Earth at the center...
- Geocentric orbitGeocentric orbitA geocentric orbit involves any object orbiting the Earth, such as the Moon or artificial satellites. Currently there are approximately 2,465 artificial satellites orbiting the Earth and 6,216 pieces of space debris as tracked by the Goddard Space Flight Center...
- List of artificial objects in heliocentric orbit
- List of orbits
- Earth's orbitEarth's orbitIn astronomy, the Earth's orbit is the motion of the Earth around the Sun, at an average distance of about 150 million kilometers, every 365.256363 mean solar days .A solar day is on average 24 hours; it takes 365.256363 of these to orbit the sun once in the sense of returning...