Search results
Results From The WOW.Com Content Network
In astronomy, coordinate systems are used for specifying positions of celestial objects (satellites, planets, stars, galaxies, etc.) relative to a given reference frame, based on physical reference points available to a situated observer (e.g. the true horizon and north to an observer on Earth's surface). [1]
This position is halfway, or 6 months, around the ecliptic from the Sun. The planet's height in the sky is opposite that of the Sun's height. The planet is at its highest at the winter solstice, and at its lowest at the summer solstice, on those (rare) occasions when it passes through the center of its retrograde motion near a solstice.
The position marks are entered inward from the distance marks according to their declinations, connected by lines (doted when positive) representing the arcs of the declinations viewed edge-on. This list covers all known stars , white dwarfs , brown dwarfs , and sub-brown dwarfs within 20 light-years (6.13 parsecs ) of the Sun .
The apparent position of a planet or other object in the Solar System is also affected by light-time correction, which is caused by the finite time it takes light from a moving body to reach the observer. Simply put, the observer sees the object in the position where it was when the light left it.
Because most planets (except Mercury) and many small Solar System bodies have orbits with only slight inclinations to the ecliptic, using it as the fundamental plane is convenient. The system's origin can be the center of either the Sun or Earth, its primary direction is towards the March equinox, and it has a right-hand convention.
The poles of astronomical bodies are determined based on their axis of rotation in relation to the celestial poles of the celestial sphere. Astronomical bodies include stars, planets, dwarf planets and small Solar System bodies such as comets and minor planets (e.g., asteroids), as well as natural satellites and minor-planet moons.
The term is also used to describe situations when all the planets are on the same side of the Sun although they are not necessarily in a straight line, such as on March 10, 1982. [ 8 ] Apparent planetary alignment involving Mercury, Venus, Mars, and Jupiter; the Moon is also shown, as the brightest object.
A small orrery showing Earth and the inner planets. An orrery is a mechanical model of the Solar System that illustrates or predicts the relative positions and motions of the planets and moons, usually according to the heliocentric model. It may also represent the relative sizes of these bodies; however, since accurate scaling is often not ...