Edexcel IGCSE Physics Unit 8 – Astrophysics Complete Guide

Edexcel IGCSE Physics Unit 8 – Astrophysics Complete Guide 1. Universe - Defined as an immense collection of billions of galaxies. 2. Galaxy - Refers to a large grouping of stars, often along with gas and dust, held together by gravitational forces. 3. Milky Way - Specifically, it's the galaxy that contains our solar system, including Earth and the Sun. 4. Solar System - Describes the entirety of celestial bodies orbiting around the Sun, encompassing planets, dwarf planets, asteroids, and comets. 5. Planet - A significant celestial body that orbits a star, typically in an almost circular orbit with a slight elliptical shape. 6. Planets in our Solar System (from closest to the Sun) - Listed as Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. 7. Dwarf Planet - Designates an object similar to a planet but smaller in size and not meeting all criteria to be classified as a full planet. 8. Moon - A natural satellite that orbits a planet in a nearly circular path. 9. Natural Satellite - Refers to a celestial object that orbits a planet naturally, without being human-made. 10. Artificial Satellite - Denotes a human-made object placed into orbit around a planet. 11. Asteroid - A solid, typically rocky or metallic object that orbits the Sun. 12. Comet - A celestial body composed mainly of ice, dust, and gas that orbits the Sun in an elongated, often highly elliptical path. 13. Circular Orbit - Describes the orbital path of an object around another body, characterized by a circular shape. Elliptical orbit ️Orbiting in a stretched circle, moving from close to a star to far away from the star. instantaneous velocity ️Velocity at a snapshot in time. orbit ️Circular motion of one object around another due to forces of gravity geostationary ️An object orbiting a planet at the same rate as the planet spins on its axis, so that it stays above the same point on that planet at all times. orbital speed ️The speed at which an object travels whilst orbiting another, more mas