4 The Sun Our Heater Our Sun is a medium-sized star called a yellow dwarf It’s at the center of our 8-planet solar system It provides heat and light and life on Earth would not exist without it From a distance it looks like a solid glowing yellow ball But it isn’t solid it’s a ball of gases like every other star The main gases that make up the Sun are hydrogen and helium HOw hOt The Sun gives off an incredible amount of heat At itGs core or center itGs 27 million Fahrenheit F At its surface itGs 9,941 F EarthGs average is 68 F This infrared photo shows flares on the Sun’s surface The heat is caused by particles called atoms of hydrogen gas found in the SunGs core The atoms bang into each other and this changes them into the gas helium This action releases huge energy and creates temperatures of millions of degrees This is what gives the Sun its heat and light Sunny facts of layers of gas around the Equator but is still 93 million miles away The Sun is the closest star to planet Earth It is more than 100 times bigger than Earth Our planet Earth orbits around the Sun the Sun does NOT orbit around Earth The Sun’s average temperature is 10,300 F The Sun is 4 6 billion years old The Sun has no solid surface It is made up
shOOting gas The surface of the Sun may look calm from a great distance away but it is really a fierce bubbling mass of fiery gases that is constantly changing shape It is continuously erupting with prominences and flares Prominences are the bright looping streams of hot gas that arch out into space They may hold their shape for months before collapsing back into the SunGs surface The visible surface of the Sun is called the photosphere prominence The chromosphere is just above the photosphere core The corona is the outer part of the Sun’s atmosphere Solar flares spurt from the surface of the Sun KEY WORDS star solar system hydrogen helium prominence flare white dwarf A dying star Unfortunately the Sun doesnGt have an unlimited amount of hydrogen fuel to convert into heat and light One day it will run out Astronomers have calculated that the Sun has enough hydrogen in its core to last another 7 billion years or so By this time it will have exhausted its reserves and switched to burning helium Then it will stop shining and become a dead star or what is known as a white dwarf
6 Shifting Liquid crust outer mantle Planet Earth is not solid In fact most of it is a churning simmering mass of white-hot rock called magma The magma floats in the outer core layer but is also present in the upper mantle This magma sometimes finds its way to the surface inner mantle outer core inner core Liquid and rOck The inner core is extremely hot In fact this central area of Earth is even hotter than the surface of the Sun Made of iron and nickel the pressure from above keeps it solid Surrounding the inner core are the outer core and inner and outer mantles and above them the surface layer of Earth called the crust A flOating crust We talk about being on solid ground but the EarthGs crust is only about 18-40 miles thick on land and up to 10 miles thick under the oceans The crust is not a single layer as you might expect It is made up of pieces known as tectonic plates that float on the upper part of the mantle
tectOnic plates As the plates have moved over millions of years theyGve bumped into and pulled apart from each other Different plates act in different ways to create mountains Those under the sea usually sink under those carrying continents They push up the continental plates Those plates carrying continents bump into each other and the edges buckle Sometimes plates rub against each other and cause earthquakes 7 KEY WORDS magma core mantle crust tectonic plate earthquake Movement in the tectonic plates causes great mountain chains to be formed
