Astronomy is a natural science that studies celestial objects, such as stars, planets, comets, and galaxies, as well as the phenomena and processes that occur in outer space.

Calcium is a chemical element with the symbol Ca and atomic number 20.

Christiaan Huygens was a Dutch scientist, mathematician, and astronomer who lived during the 17th century.

Coordinated Universal Time (UTC) is the primary time standard by which the world regulates clocks and time.

Galileo Galilei (1564-1642) was an Italian polymath who made significant contributions to the fields of physics, astronomy, mathematics, and philosophy.

Gravity is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are brought toward one another.

The Great Exhibition was a world's fair held in London in 1851.

Grubb Parsons (legally 'Sir Howard Grubb, Parsons and Co.