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The greatest elongation of a given inferior planet occurs when this planet's position, in its orbital path around the Sun, is at tangent to the observer on Earth. Since an inferior planet is well within the area of Earth's orbit around the Sun, observation of its elongation should not pose that much a challenge (compared to deep-sky objects, for example).
The vector algebra to derive the standard formula is equivalent to the calculation of the long derivation for the compass course. The sign of the angle is basically kept, north over east in both cases, but as astronomers look at stars from the inside of the celestial sphere, the definition uses the convention that the q is the angle in an image that turns the direction to the NCP ...
The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar System and the interstellar medium . The study of the abundance of elements and isotope ratios in Solar System objects, such as meteorites , is also called cosmochemistry , while the study of interstellar atoms and molecules and ...
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a ...
Coordinate systems in astronomy can specify an object's relative position in three-dimensional space or plot merely by its direction on a celestial sphere, if the object's distance is unknown or trivial. Spherical coordinates, projected on the celestial sphere, are analogous to the geographic coordinate system used on the surface of Earth.
In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle.
Within a few million years the light from bright stars will have boiled away this molecular cloud of gas and dust. The cloud has broken off from the Carina Nebula.Newly formed stars are visible nearby, their images reddened by blue light being preferentially scattered by the pervasive dust.
Cosmic dust is made of dust grains and aggregates into dust particles. These particles are irregularly shaped, with porosity ranging from fluffy to compact. The composition, size, and other properties depend on where the dust is found, and conversely, a compositional analysis of a dust particle can reveal much about the dust particle's origin.