The Sun Chapter 3 Lesson 6 Page 122

What is the structure of the Sun Does not have a solid surface ¾ hydrogen, ¼ helium Tiny amounts of other elements can also be found The sun has an interior and atmosphere. The interior includes the core, the radiation zone, and the convection zone

The Core The sun produces an enormous amount of energy in its core. Core-central region where nuclear fusion takes place Nuclear fusion- hydrogen atoms join to form helium It requires extremely high temperatures and pressure The mass of the helium is slightly less than the hydrogen that created it, the rest is energy

Radiation Zone The energy produced in the sun’s core moves out-ward through the radiation zone Radiation zone- a region of very tightly packed gas where energy moves mainly in the form of electromagnetic radiation Very dense can take energy more than 100,000 years to move through it!!!

The Convection Zone Convection Zone- the outermost layer of the sun’s interior Hot gases rise from the bottom of the convection zone and gradually cool as they approach the top Cooler gases sink, forming loops of gas that moves energy towards that sun’s surface

The Sun’s Atmosphere The Sun’s atmosphere stretches far into space The further away from the radiation zone, the less dense the layers of the atmosphere become Primarily composed of hydrogen and helium The sun’s atmosphere includes the photosphere, the chromosphere, and the corona. Each layer has unique properties

The Photosphere Photosphere- The inner layer of the sun’s atmosphere that gives off its visible light, (the surface layer) The surface is not solid, but the photosphere is so dense it is visible This is the part of the sun you see when looking at it in pictures

The Chromosphere Chromosphere- the middle layer of the sun’s atmosphere This layer causes the reddish glow at the end of a total eclipse The word “chroma” is the Greek word for color So Chromosphere means “color sphere”

The Corona During solar eclipse, a fainter layer shows Corona- the outer layer which looks like a halo around the sun, it extends into space for millions of kilometers It gradually thins into streams of electrically charged particles called the solar wind Solar wind- a stream of electrically charged particles that emanate from the sun’s corona

What Features Can you See on the Sun? Specialized telescopes have seen a number of features on the sun’s surface Features on or just above the sun’s surface include, sunspots, prominences, and solar flares

Sunspots Photographs show dark areas in on the sun’s surface Sunspots- areas of gas on the sun’s surface that are cooler than the gases around them Cooler gases give off less light than hotter gases, so the sun spots look dark The number of sunspots vary and change every few years. The sun emits slightly more radiation when there are more sunspots

Prominences Sunspots usually occur in groups Prominences- huge reddish loops of gas that protrudes from the sun’s surface that link different parts of sunspot regions.

Solar Flares Sometimes loops in sunspot regions suddenly connect, releasing large amounts of magnetic energy The energy heats gas on the sun to millions of degrees Celsius causing gas to erupt in space Solar Flares- an eruption of gas on the sun’s surface that occurs when loops from sunspot regions connect

Left-This is an image of the sun as seen through a special filter Left-This is an image of the sun as seen through a special filter. The strong radiation from a solar flare is seen as a bright spot on the right. Do not look directly at the sun, it can hurt your eyes. Image Credit: NASA Right- multiple solar flares

Solar Wind Solar wind is made of electrical particles from the sun Solar flares greatly increase solar wind Some of these particles can reach Earth’s atmosphere which will block most of them. However some of the particles enter and have strange effects on the north and south poles Read page 127