SI
The International System of Units (metric system).
One of from which all the other SI units are derived. See SI derived unit.
Of, relating to, or concerned with the stars. Sidereal rotation is that measured with respect to the stars rather than ...
The average period of revolution of the Moon around the Earth in reference to a fixed star, equal to 27 ...
The period of revolution of a planet around the Sun or a satellite around its primary.
A measure of time by the stars, sidereal time marks the right ascension of stars on your local meridian at ...
The center of a black hole, where the curvature of space time is maximal. At the singularity, the gravitational tides ...
Small Magellanic Cloud, the smaller of two small galaxies orbiting nearby our Milky Way galaxy, which are visible from the ...