The Sun

A Representative Star

In many ways the Sun is a perfect representative for all stars because it is so average.  Compared to other stars the Sun has:

  • Average Size
  • Average Luminosity
  • Average Temperature
  • Average Density
  • Middle Age

 

For us it's exceptional

While it may be average compared to other stars, here on Earth we would consider the Sun anything but exceptional.  In fact it is of the upmost importance to our planet for several reasons:

  • It is the ultimate source of energy for our planet and all life that exists here.  In fact it produces enough energy per second to meet all of humanity's energy needs for the next 500,000 years!
  • It has been worshiped as a God by nearly every civilization at one point or another
  • it is 1.3 million times larger than the Earth.

The Structure and Composition of the Sun

The Sun's Composition

The Sun like all stars is a massive sphere of gas.  The Sun is made up almost entirely of 2 gasses:

  • 74% Hydrogen
  • 24% Helium

The hydrogen that makes up the majority of our Sun is used as fuel for the Sun's fusion reaction, which produces helium. 

 

 

 

The Sun's STRUCTURE

The Sun has a layered structure made up of a core surrounded by 3 exterior layers:

The Photosphere

The photosphere is the layer of the Sun that surrounds the core.  The photosphere is the visible part of the Sun, from which light is emitted.  

When viewed from outside of our atmosphere we get a clear view of the photosphere which shows its grannular appearance.  This grannular appearance is caused by regions of different tempearture, where darker splotches are cooler than brighter splotches.

 

The Chromosphere

The Chromosphere is outside of the photosphere.  One odd thing about the Chromosphere is that the temperature of the Sun increases as you move farther out towards the edge of the chromosphere.  

Spicules are jet like fountains that erupt out from the surface of the chromosphere.

The corona

The corona is the very hot outermost layer of the Sun.

It is only visible during a total solar eclipse, when the Moon blocks out the photosphere.  

Prominenes are huge arcs of gas and plasma that erupt out from the Corona.

 

Solar Storms

Sun spots

SUNSPOTS ARE REGIONS OF INTENSE MAGNETIC ENERGY THAT APPEAR AS DARK SPOTS ON THE SURFACE OF THE PHOTOSPHERE.  

SUNSPOTS ARE CAUSED BY MAGNETIC ENERGY GENERATED BY THE SUN.

Sunspots appear in areas where massive amounts of magnetic energy are focused into a small area on the photosphere.  They usually appear in groups, 

Solar Flares

As more and more magnetic energy builds up near a sunspot, the region becomes more unstable.  When all of the magnetic energy built up in the sunspot erupts out from the photosphere it creates a SOLAR FLARE.

Solar flares release huge amounts of energy that shoots outwards into space.  If the energy reaches the Earth is creates Geomagnetic Storms that have dramatic effects on our planet and our civilizations.

  • Create the Northern Lights (Aurora Borealis)
  • Can damage satelites in orbit
  • Can cause blackouts on Earth

Aurora Borealis

When the charged particles shooting out from the Sun after a solar flare hit the Earth's magnetic field, that energy is all pushed towards the North and South Pole.  Here the charged particles in Earth's outer atmosphere called the ionosphere are excited causing them to glow.  This creates a phenomenon called the Aurora Borealis - the northern lights.  It is caused by Geomagnetic Storms.

DAMAGE TO ELECTRONICS

A particularly strong solar storm triggered by a massive solar flare hitting the Earth could do tremendous damage to our electronics infrastructure.  The electromagnetic energy released by solar storms is capable of frying electronics that aren't protected by a magnetic field.  

Our satellites that are used for navigation, communication, weather prediction, and observation orbit the Earth outside of our protective magnetic field. A strong solar storm could potentially destroy the entire fleet of satellites making them useless junk.

A VERY strong solar storm that had a DIRECT hit on Earth could also possibly wipe out ground based electronics and electrical grids causing widespread blackouts.