Download The Sun: A Medium-sized Star

The Sun: A Medium-sized Star
Learning Goals
 I will be able to describe the make up of the sun.
 I will be able to explain the sun’s role in the survival of things on earth.
The Sun
 star at centre of Solar System.
 warms our planet and provides light and thermal energy.
 Processes, or reactions, occurring inside our Sun provide this energy.
 very important to life on Earth.
Layers of the Sun
 composed of many different layers, with each layer performing different activities.
 layers composed of gases.
 no solid surface like Earth, but it does have a definite structure.
The Core
 nuclear reactions occur that change the composition and energy of atomic nuclei.
 Atoms of hydrogen (H) fuse, or join, to form atoms of helium (He).
 These nuclear reactions release immense amounts of energy, causing the Sun’s core to
reach temperatures of about 15 million °C.
From the Core to the Atmosphere
 Energy produced in core moves outward into the next layer, the radiative zone.
 The energy moves outward into the convective zone, where cool matter sinks and hot
matter rises.
 Photosphere: Suns surface where energy escapes as light.
 Atmosphere: is divided into the chromosphere and the corona.
 Chromosphere: inner atmosphere, very hot—about 60 000 ºC hotter than the
photosphere!
 Cornona: The thin outer layer that glows brilliantly.
 It extends millions of kilometres into outer space.
The Sun’s Surface Features
 Sunspot: dark region of cool matter on the photosphere, caused by twists in the Sun’s
magnetic field.
 vary in both size and regularity.
 Often, sunspots appear in pairs of opposite polarity.
 Solar flare is a huge explosion of gas and charged particles
 Often found near sunspots,
 release huge amounts of energy
 can reach temperatures of tens of millions of degrees Celsius.
Energy from the Sun
 Every second, the Sun releases enough energy to meet the needs of every person on
Earth for the next 500 000 years.
 The Sun is the driving force behind Earth’s climate and weather and also provides the
energy needed for life to exist on Earth
• Plants use sunlight to grow and to produce food.
• Animals eat plants that are grown in sunlight.
• Coal formed from the remains of prehistoric plants; form of stored energy from the Sun.
• Oil formed from fossils, which obtained energy from plants, and hence, the Sun.
The Auroras
 The Sun’s corona is constantly releasing electrically charged particles into space at
speeds of up to 400 km/s.
 travelling particles are known as the solar wind.
 Earth’s atmosphere contains atoms of different gases.
 Earth surrounded by magnetic field.
 Particles of solar wind spiral along the lines of the magnetic field.
 As the particles move toward the poles and strike the gases in Earth’s atmosphere, a light
display called an aurora is produced.
 Known as the Northern Lights
Learning Goals Revisited
 I will be able to describe the make up of the sun.
 I will be able to explain the sun’s role in the survival of things on earth.
Complete
1. Where do the Sun’s nuclear reactions take place?
2. Create a graphic organizer describing light’s journey from the core of the Sun to Earth.
3. How are solar flares different from sunspots?
4. Describe how the Sun indirectly powers gasoline-powered automobiles.
5. The Sun produces more than enough energy to meet our needs. Suggest ways we could
use the Sun’s energy more effectively.
6. How would you explain to a friend how an aurora forms?