The Sun• Average in size… yes

AVERAGE!! • Mass is almost 340 000

times that of Earth and a volume that is 1 300 000 times the volume of Earth!

• Appears to be so much bigger and brighter than other stars because it is so close to Earth

• The earth is 150 000 000 (1.5 x 108) km from the sun

1 Astronomical Unit (A.U.) = distance from sun to earth

• The next nearest star to the Sun is Proxima Centauri at 40 trillion (4.01 x 1013) km from Earth.

• Most stars are more than 100 trillion (1.0 x 1014) km from Earth.

The Structure of the Sun

The Sun’s SurfaceSunspots• dark surface spots that are cooler than surrounding area

Solar Flares• gases and charged particles expelled above the active

sunspot

Solar Prominences • low-energy gas eruptions

from the Sun’s surface that extends thousands of kilometres into space

Layers of the Sun’s AtmosphereAbove the surface of the sun is its atmosphere, which

consists of three parts:

Corona• 5800 oC• gleaming white, halo-like – extends millions of kms into

space

Chromosphere • 65 500 oC

Photosphere• 5 500 oC • The layer just below the Chromosphere where the light

we see originates.

Core• hottest part of the Sun - reaching 15 000 000 oC • Energy released by nuclear fusion continues to move

outward until it reaches the photosphere

Convective zone • The outermost ring of the sun, comprising the 30 percent

of its radius.

Radiative zone • The section immediately surrounding the core, comprising

45 percent of its radius.

The Inside of the Sun

Composition 75% hydrogen25% helium (with small amounts of other gases)

Energy Source• process called nuclear

fusion occurring in its core

• the temperature and pressure are so high H fuses to become He and releases tremendous amounts of energy

The Sun’s Effects on Earth

The Aurora Borealis (Northern Lights)

• The Northern Lights are the result of collisions between gaseous particles in the Earth's atmosphere with charged particles released from the sun's atmosphere.

Solar winds travelling toward Earth follow the lines of magnetic force created by Earth’s magnetic field (which is strongest near the NORTH and SOUTH poles).

Near the poles, they come in contact with particles in Earth’s atmosphere, producing a display of light in the night sky.

Northern Lights = Aurora BorealisSouthern Lights = Aurora Australis

Class/Homework• Pg. 312 #1, 2, 6, 8, 9