Astronomy 1021 Lecture Notes - Lecture 1: Hubble Deep Field, List Of Largest Galaxies, Observable Universe

• School: Western University
• Department: Astronomy
• Course: Astronomy 1021
• Professor: Robert Cockcroft

Document Summary

Star: a spherical object that generates energy through nuclear fusion (h -> he) Stars twinkle, planets do not (atmospheric turbulence) When looking at planet we can see a disc, stars we can only see pinpoint of light. Planet: a spherical object that orbits a star; dominates its orbit; reflects light; rock, ice, gas. Moon (a. k. a. satellite): an object that orbits a planet. Solar system: the region around a star that includes planets, moons, other small bodies. Galaxy: very big collection of stars (and solar systems), gas, dust, and dark matter. Nebula (latin for cloud): huge interstellar clouds of gas. Universe: the entirety of everything we know of; time, space and all its contents. Most of the blobs are distant galaxies. The universe is littered with billions of galaxies. We have experience with data storage for example. Sn is a shorthand way for describing numbers. E. g. 1 billion can be described as 1 followed by 9 zeros.