The Sun The Sun Our closest star a

The Sun

The Sun • Our closest star (a yellow dwarf) • Source of all energy on Earth • Located 149 million km from Earth or 1 AU (Astronomical Units) • Light takes a million years to get from the core to the Sun’s surface but only 8 minutes to reach us

The Sun • Rotates on its axis and orbits the galaxy, same as us • About half way through its 10 billion year life cycle • Sun will swell into a red giant, then cool to form a brown or black dwarf

The Sun

The Core • 25% of its radius • Intense pressure causes nuclear fusion – atoms of hydrogen fuse to form helium • Gives off huge amounts of energy (a billion 1 Mt nuclear blasts per second)

The Interior Radiative Zone • 45% of Sun’s radius • Energy carried out by photons (light energy) • Takes huge amount of time to get through

The Interior Convective Zone • 30% of Sun’s radius • Waves of hot gas • Carry energy outward to surface

The Atmosphere • Made up of 3 parts: the photosphere, the chromosphere, and the corona

The Atmosphere Photosphere • The surface of the Sun • 300 – 400 km wide • 6000˚ Celsius

The Atmosphere Chromosphere • Above photosphere (about 2000 km) • Convection currents cause temp. to rise to 10000˚ Celsius

The Atmosphere Corona • Extend millions of km out in space • Best seen during a solar eclipse or X-ray of the Sun • About 1000000˚C – perhaps due to Sun’s magnetism

Solar X-Ray Photosphere Chromosphere Corona

Other Features Sunspots • Darker, cooler regions on the surface • Intense magnetic field • Runs in an 11 year cycle (2010 is when sunspots are at a minimum)

Other Features Prominences • Clouds of gas from the chromosphere • Rise up along magnetic lines from sunspots Solar Flares • Violent eruptions from the Sun • Release intense radiation which cause auroras (Northern Lights)

Life of a Star • The fate of a star depends on its size Dwarf Stars • Like our sun, will swell up (red giant) then slowly burn out (white dwarf then black dwarf) • Will take several billion years

Fate of the Sun • http: //videos. howstuffworks. com/scienc e-channel/6566 -destiny-the-suns-fatevideo. htm

Life of a Star Huge or Giant Stars • Will become a supergiant, then explode into a supernova (core instantly collapses) • Eventually ends up as a neutron star or a black hole

Neutron Star • 1. 5 – 3 times mass of Sun • Core shrinks to diameter of 10 km, mass still double the Sun • Huge magnetic field and rapid spin

Black Hole • > 3 times mass of Sun • Contracts tremendously • Gravitation pull so strong not even light can escape!