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Nebulae. Space clouds. What is a Nebula?. A nebula is an interstellar cloud of 90% hydrogen, 10% helium, & trace amounts of heavier elements Nebulae are the basic building blocks of our universe, and contain the elements from which stars and solar systems are made.
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Nebulae Space clouds
What is a Nebula? • A nebula is an interstellar cloud of 90% hydrogen, 10% helium, & trace amounts of heavier elements • Nebulae are the basic building blocks of our universe, and contain the elements from which stars and solar systems are made. • They are the biggest things in our galaxy. Ranging from a dozen to hundreds light-years across.
Different Types of Nebulae There are five different types of Nebulae: • Emission • Reflection • Dark • Planetary • Supernova Remnants.
Emission Nebulae • Usually red • Are clouds of high temperature gas. Energized by ultraviolet light from nearby stars they emit radiation • Usually the sites of recent and ongoing star formation.
Reflection Nebulae • Usually blue • Clouds of dust that reflect the light from a nearby star. • Usually found at “star formation” sites and are mostly found near Emission Nebulae • Sometimes referred to as Defuse Nebulae.
Dark Nebulae • Are so dense they block the light coming from whatever is behind it • Dust grains located at the coldest densest parts of the molecular cloud block the light.
Planetary Nebulae • Shells of gas usually thrown out when stars similar to our Sun die. • Are usually one light-year across • Once mistaken for planets they have nothing to do with them. • Have very short lives, only lasting a few ten thousands years. • The ultraviolet radiation from the core ionizes the ejected layers and make them emit light.
Supernova Remnants • Created when a massive star ends its life in a supernova. • They have a chaotic appearance