Lesson 3 - Stars in the night Sky

What is a star

10 billion trillion stars in the universe, hot dense ball of gas that gives off light and other forms of radiation from nuclear reactions in its core, releases energy as electromagnetic radiation in all directions which is why stars shine

Nebula

A giant cloud of gas and dust in space where stars are formed. Nebulae can also be remnants of dead or dying stars (supernova) , often glowing or reflecting light from nearby stars

How are stars born?

nebulae collects enough additionall gas and dust so the protostar’s core reaches a high enough temp. nuclear fusion begins

List the star’s colours from coolest to hottest

red, orange, yellow, white, blue-white (temps up to 40,000 C)

List the four main groups of stars

Main Sequence, Supergiants, Giants, White Dwarfs

What is a galaxy

massive group of stars, gas, dust held together by gravity (several billion galaxies in the universe, each with billions of stars) each galaxy is thought to have a black hole at the centre

Closest galaxy to earth

Andromeda

Three types of galaxies

Elliptical, Spiral, Irregular

Elliptical

nearly circular, lacks gas/dust, contains the oldest stars, product of galactic collisions

Spiral

broad, flat, rotating disks, stars, gas, dust, central brightness, extending spiral arms, lots of young stars

Irregular

small, patchy, lack identifiable shape, large amounts of gas and dust

Drake equation

A formula used to estimate the number of detectable extraterrestrial civilizations in the Milky Way galaxy, considering factors such as star formation rates and the presence of habitable planets