Computer science

Computer science, or computing science, is the study of the theoretical basics of information and calculation and their execution and application in computer systems. Computer science has lot of sub-fields; a few highlight the calculation of exact consequences (such as computer graphics), whereas others (such as computational complexity theory) relate to properties of computational difficulties. Still others focus on the challenges in applying calculations. For instance, programming language theory studies move toward to describe calculations, whereas computer programming applies precise programming languages to answer precise computational difficulties.

Star

A star is a massive, luminous ball of plasma. Stars group together to form galaxies, and they dominate the visible universe. The nearest star is the Sun, which is the source of most of the energy on Earth, including daylight. Other stars are visible in the night sky, when they are not outshone by the Sun. A star shines because nuclear fusion in its core releases energy which traverses the star's interior and then radiates into outer space. Without stars, life on Earth and most atomic elements would not exist.


Astronomers can determine the mass, age, chemical composition and many other properties of a star by observing its spectrum, luminosity and motion through space. The total mass of a star is the principal determinant in its evolution and eventual fate. Other characteristics of a star that are determined by its evolutionary history include the diameter, rotation, movement and temperature. A plot of the temperature of many stars against their luminosities, known as a Hertzsprung-Russell diagram (H-R diagram), allows the current age and evolutionary state of a particular star to be determined.