The Sun –Energy for Life
The Sun is the star at the center of the Solar System, the most important source of energy for life on Earth. The sun is a sphere of hot plasma, with internal convection currents that generate a magnetic field. Its diameter is 109 times that of Earth and its mass is 330,000 times bigger than earth’s. Three quarters of the Sun's mass consists of hydrogen (73%), the rest is mostly helium (25%), with smaller quantities of oxygen, carbon, neon, and iron.
The sun’s energy output is created by hydrogen fusion that creates electromagnetic radiation and helium. The Sun has an absolute magnitude of +4.83, estimated to be brighter than about 85% of the stars in our galaxy, most of which are red dwarfs. The sun rotates and releases energy in all frequencies of the electromagnetic spectrum. The surface is turbulent with moving sunspots, solar flares and coronal mass ejections. High-speed streams of solar wind are emitted from coronal holes. Both coronal-mass ejections and high-speed streams of solar wind carry plasma and an interplanetary magnetic field outward into the Solar System. The surface temperature of the photosphere is approximately 6,000 K, but surprisingly the temperature of the surrounding corona reaches 1,000,000–2,000,000 K.
Despite the sun’s obvious turbulence, animals and plants on earth humans have
depended on its relative stability. A recent and serious concern is that the sun
can produce magnetic storms that would disable or destroy our electric grids
and electronics. Most solar disturbances are reflected by our magnetic field or
absorbed by the atmosphere. However, infrequent large events can be anticipated.
Geomagnetic storms have caused solar energetic Particle (SEP) events, geomagnetically induced currents (GIC), ionospheric disturbances that cause
radio and radar scintillation, disruption of navigation by magnetic compass and
auroral displays at much lower latitudes than normal. In 1989, a geomagnetic
storm energized ground induced currents that disrupted telegraph networks,
electric power distribution and caused aurorae as far south as Texas. NASA
operates continuous sun observations. Their understanding of solar flares is
advancing. NASA described:” Solar flares are intense bursts of light from the
sun. They are created when complicated magnetic fields suddenly and explosively
rearrange themselves, converting magnetic energy into light. During a December
2013 solar flare, three solar observatories captured the most comprehensive
observations of an electromagnetic phenomenon called a current sheet. These
eruptions on the sun eject radiation in all directions. The strongest solar
flares can impact the ionized part of Earth’s atmosphere – the ionosphere – and
interfere with our communications systems, like radio and GPS, and also disrupt
onboard satellite electronics. Additionally, high-energy particles – including
electrons, protons and heavier ions – are accelerated by solar flares.