Unit 7 Astronomy 7.0 What does our universe look like? – Individual Planets and Earth Diameter: 12 742 km Age: 45 by Tilt: 23.4° Volume: 1.08x1012 km3 Gravity: 9.8 m/s2 Planetary Systems Earth System Involves planets with their About the moon: moons. Diameter: 3474 km Age: 4.5 byo Volume: 2.196x1010 km3 Gravity: 1.6 m/s2 Star Systems Solar System Planets, asteroids, comets, etc. Orbital speed: 220 km/s orbiting around a star Orbital period: 225-250 my Distance to galaxy center: 25 000 ly Galaxy Milky Way Galaxy Collection of star systems, all Age: 13.2 by orbiting around the same centre Number of stars: approx. 100 billion of mass. Diameter: 100 000 ly Galaxy Cluster Local Group A small group of galaxies Contains ~54 galaxies ~300 catalogued so far. Largest galaxies are Milky Way and Andromeda (2 mly away) Super Cluster Supercluster (Galaxy Supercluster) Contains thousands of clusters Contains ~2500 galaxies
Unit 7 Astronomy 7.0 – What does our universe look like? Individual Planets and Earth Diameter: 12 742 km Age: 45 by Tilt: 23.4° Volume: 1.08x1012 km3 Gravity: 9.8 m/s2 Planetary Systems Involves planets with their moons. Earth System About the moon: Diameter: 3474 km Age: 4.5 byo Volume: 2.196x1010 km3 Gravity: 1.6 m/s2 Star Systems Planets, asteroids, comets, etc. orbiting around a star Solar System Orbital speed: 220 km/s Orbital period: 225-250 my Distance to galaxy center: 25 000 ly Galaxy Collection of star systems, all orbiting around the same centre of mass. Milky Way Galaxy Age: 13.2 by Number of stars: approx. 100 billion Diameter: 100 000 ly Galaxy Cluster A small group of galaxies ~300 catalogued so far. Local Group Contains ~54 galaxies Largest galaxies are Milky Way and Andromeda (2 mly away) Super Cluster Contains thousands of clusters Supercluster (Galaxy Supercluster) Contains ~2500 galaxies
07_-_astronomy_student_notes.docx