The Sun
Intro to the Universe
Our Sun
• The sun is approximately 4.6
billion years old
• The sun is extremely hot
• 15,000,000 K at the center
• 5800 K at the surface
• Temperature is so hot, that most
of the matter is plasma
• 70% of the Sun is hydrogen,
28% is helium
Energy from the Sun
• Sun provides energy to all
objects in the Solar System by
fusion
Energy from the Sun Fusion
Energy from the Sun
• Sun provides energy to all
objects in the Solar System by
fusion
• Small hydrogen nuclei (not
atoms) collide and fuse into
helium
• During the process, some mass
is converted into energy
• E = mc2
How does the Sun stay
stable?
• The tremendous heat at the Sun
means that particles move very
quickly
• The large mass means that
there is a huge amount of
gravity
• These forces balance and the
Sun remains stable and
consistent
Sun’s Interior Structure
• Core
• Central region of the Sun
• Where nuclear fusion occurs
• Diameter of 400000 km (1/4 the
diameter of the Sun)
Sun’s Interior Structure &
Atmosphere
Sun’s Interior Structure
• Core
• Radiation Zone
• A region of highly compressed
gases
• So dense that energy produced by
fusion in the core may take
100000 years to pass through it
Sun’s Interior Structure &
Atmosphere
Sun’s Interior Structure
• Core
• Radiation Zone
• Convection Zone
• Outer layer of the Sun’s interior
• Energy transferred outward by
convection currents
Sun’s Interior Structure &
Atmosphere
Sun’s Atmosphere
• Photosphere
• Innermost layer of the Sun’s
atmosphere
• Visible “surface” of the Sun
• “Bubbly” appearance from
convection currents in Convection
Zone
Sun’s Interior Structure &
Atmosphere
Sun’s Atmosphere
• Photosphere
• Chromosphere
• Middle layer of Sun’s atmosphere
• Temperature increase causes
gases to emit a “reddish” light, but
not very bright
Sun’s Interior Structure &
Atmosphere
Sun’s Atmosphere
• Photosphere
• Chromosphere
• Corona
• Outermost layer of Sun’s atmosphere
• Very thin, but very hot layer
• As it proceeds outward and thins out, it
turns into “solar wind”
• Stream of charged particles, which interacts
with the magnetic field of the Earth
• Causes aurora borealis near the poles when it
enters Earth’s atmosphere
Sun’s Interior Structure &
Atmosphere
Features of the Sun’s
Atmosphere
• Sunspots
• Small, dark colored regions in
photosphere
• Cooler than surrounding areas
Sunspots
Features of the Sun’s
Atmosphere
• Sunspots
• Prominences
• Huge loops of gas that erupt from
sunspot regions
Solar Prominence
Features of the Sun’s
Atmosphere
• Sunspots
• Prominences
• Solar Flares
• Eruption of the Sun’s surface
• Huge amounts of energy (X-rays) and
high speed charged particles released
into space
• The energy & high speed particles can
disrupt electric power and energy
transmission here on Earth
Solar Flare