- Absolute magnitude (Wikipedia)
In astronomy, absolute magnitude (M) is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object’s absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs (32.6 light-years), without extinction (or dimming) of its light due to absorption by interstellar matter and cosmic dust. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared among each other on a magnitude scale. For Solar System bodies that shine in reflected light, a different definition of absolute magnitude (H) is used, based on a standard reference distance of one astronomical unit.
- Strait (Wikipedia)
A strait is a landform connecting two seas or two water basins. While the landform generally constricts the flow, the surface water still flows, for the most part, at the same elevation on both sides and through the strait in both directions. In some straits there may be a dominant directional current through the strait. Most commonly, it is a narrowing channel that lies between two land masses. Some straits are not navigable, for example because they are either too narrow or too shallow, or because of an unnavigable reef or archipelago. Straits are also known to be loci for sediment accumulation. Usually, sand-size deposits occur on both the two opposite strait exits, forming subaqueous fans or deltas.