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Solar conjunction generally occurs when a
Solar conjunction generally occurs when a planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
or other Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
object is on the opposite side of the Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
from the Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
. From an Earth reference, the Sun will pass between the Earth and the object. Communication with any spacecraft
A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, p ...
in solar conjunction will be severely limited due to the Sun's interference on radio transmissions from the spacecraft.
The term can also refer to the passage of the line of sight to an interior planet (Mercury
Mercury commonly refers to:
* Mercury (planet), the nearest planet to the Sun
* Mercury (element), a metallic chemical element with the symbol Hg
* Mercury (mythology), a Roman god
Mercury or The Mercury may also refer to:
Companies
* Merc ...
or Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...
) or comet being very close to the solar disk. If the planet passes directly in front of the Sun, a solar transit
In astronomy, a solar transit is a movement of any object passing between the Sun and the Earth. This mainly includes the planets Mercury and Venus. A solar eclipse is also a solar transit of the Moon, but technically only if it does not cover ...
occurs.
Spacecraft-related issues
There is also a risk that an antenna equipped with auto-tracking will begin following the Sun's movements instead of the satellite once they are no longer inline with each other. This is because the Sun acts as a large electromagnetic noise generator which creates a signal much stronger than the satellite's tracking signal. One example of limitations caused by the solar conjunction occurred when theNASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
- JPL team put the Curiosity rover
''Curiosity'' is a car-sized Mars rover designed to explore the Gale crater on Mars as part of NASA's Mars Science Laboratory (MSL) mission. ''Curiosity'' was launched from Cape Canaveral (CCAFS) on November 26, 2011, at 15:02:00 UTC and lan ...
on Mars' surface in autonomous
In developmental psychology and moral, political, and bioethical philosophy, autonomy, from , ''autonomos'', from αὐτο- ''auto-'' "self" and νόμος ''nomos'', "law", hence when combined understood to mean "one who gives oneself one's ow ...
operation mode for 25 days during the conjunction. In autonomous mode Curiosity
Curiosity (from Latin '' cūriōsitās'', from ''cūriōsus'' "careful, diligent, curious", akin to ''cura'' "care") is a quality related to inquisitive thinking such as exploration, investigation, and learning, evident by observation in humans ...
suspends all movements and active science operations but retains communication-independent experiments (e.g. record atmospheric and radiation data). A more recent example occurred with the Mars rover Perseverance
Perseverance may refer to:
Behaviour
* Psychological resilience
* Perseverance of the saints, a Protestant Christian teaching
* Assurance (theology)
Geography
* Perseverance, Queensland, a locality in Australia
* Perseverance Island, Seychelles
...
in October of 2021.
See also
*Conjunction (astronomy and astrology)
In astronomy, a conjunction occurs when two astronomical objects or spacecraft have either the same right ascension or the same ecliptic longitude, usually as observed from Earth.
When two objects always appear close to the ecliptic—such as two ...
* List of conjunctions (astronomy)
* Opposition (astronomy)
In positional astronomy, two astronomical objects are said to be in opposition when they are on opposite sides of the celestial sphere, as observed from a given body (usually Earth).
A planet (or asteroid or comet) is said to be "in opposition" ...
References
Astrological aspects Conjunctions (astronomy and astrology) Satellite broadcasting Spaceflight concepts {{sun-stub