NATS 1740 Lecture Notes - Lecture 1: Cosmic Calendar, Solar System, Spiral Galaxy

• School: York University
• Department: Natural Science
• Course: NATS 1740
• Professor: Tatiana Paulin

Document Summary

Scienti c notation: the system of recording very large or very small numbers to the power of 10. Light year (ly: distance that light travels in the period of one years (light taels at 300,000 km/s) Astronomical unit (au: average distance from earth to the sun (1. 5x 10^8 km) Atom: the nucleus of an atom in 10-billionth of a meter, nucleus of the atom is 10 thousand times smaller than the atom itself. 80,000 light years and contains 100 billion stars. 10^5 ly = 100,000 ly = 10^21 m. Planet: a non-luminous body in orbit around a star, large enough to be spherical, large enough to have cleared its orbital zone of other objects, earth, orbits our star (the sun) once a year. Star: a globe of gas held together by its own gravity, supported by the internal of its hot gases, which generate energy by nuclear ssion.