page_title: Opposition (astronomy)
section_title: See also
hierarchical_section_title: Opposition (astronomy) / See also
caption_attribution_description: English: This image shows our neighbouring planet Mars, as it was observed shortly before opposition in 2016 by the NASA/ESA Hubble Space Telescope. Some prominent features of the planet are clearly visible: the ancient and inactive shield volcano Syrtis Major; the bright and oval Hellas Planitia basin; the heavily eroded Arabia Terra in the centre of the image; the dark features of Sinus Sabaeous and Sinus Meridiani along the equator; and the small southern polar cap.
context_page_description: 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.
  A planet is said to be "in opposition" when it is in opposition to the Sun. Because most orbits in the Solar System are nearly coplanar to the ecliptic, this occurs when the Sun, Earth, and the body are configured in an approximately straight line, or syzygy; that is, Earth and the body are in the same direction as seen from the Sun. Opposition occurs only for superior planets.
  The instant of opposition is defined as that when the apparent geocentric celestial longitude of the body differs by 180° from the apparent geocentric longitude of the Sun.
  At that time, a body is:
  in apparent retrograde motion
  visible almost all night – rising around sunset, culminating around midnight, and setting around sunrise
  at the point in its orbit where it is roughly closest to Earth, making it appear larger and brighter
  nearly completely sunlit; the planet shows a full phase, analogous to a full moon
  at the place where the opposition effect increases the reflected light from bodies with unobscured rough surfaces
context_section_description: Conjunction
  Phase angle
  Spherical astronomy
  Syzygy
caption: Mars in opposition 2016.[8]
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