The SunChapter 14.2

StandardO 8.2.g. Students know the role of

gravity in forming and maintaining the shapes of planets, stars and the solar system

O 8.4.b. Students know that the sun is one of many stars in the Milky Way galaxy and that stars may differ in size, temperatures, and color.

IntroductionO The sun

accounts of 99.8 percent of the solar system’s total mass.O The sun exerts

a powerful gravitation force throughout the entire solar system,

Energy from the SunO¾ of the sun’s mass

is hydrogenONuclear Fusion

O The sun produces energy through nuclear fusion.

O Nuclear Fusion: two atomic nuclei combine forming a larger more massive nucleus and releasing energy

Energy from the Sun

Energy from the SunO Core: the central region of the sunO The temperature within the core

reaches about 15 million degrees Celcius

O This energy reaches Earth as light and heat

O Forces in BalanceO Astronomers estimate that the sun

will be stable for another 5 billion years or so

The Sun’s InteriorO The sun’s interior

consists of the core, the radiation zone, and the convection zone

O The Core: 400,000 km, more than 30 times the Earth’s Diameter

The Sun’s InteriorO The Radiation Zone:

region of very tightly packed gas where energy is transferred mainly in the form of electromagnetic radiation

O The Convection Zone: The outermost layer of the sun’s interior.

The Sun’s AtmosphereO The sun’s atmosphere includes the

photosphere, the chromosphere, and the corona

O The Photosphere: part of the sun that gives off visible lightO Photos = light

The Sun’s AtmosphereO The Chromosphere: The glow comes

from this layerO Chroma = color

O The Corona: Looks like a white halo around the sunO In Latin = CrownO Extends into space for millions of

kilometers, and gradually thins into streams of electrically charges particles called the solar wind

The Corona

Features on the Sun

O Features on or just above the sun’s surface include sunspots, prominences and solar flares.O Sunspots: areas of gas on the sun’s

surface that are cooler than the gases around themO Since the sunspots seems to change

location, this means the sun rotates on its axis, like the Earth does.

Features on the SunO Prominences: huge, reddish loops of

gasO Solar Flares: eruptions that happen

on the sunO Solar Wind: can affect Earth’s

magnetic field.