Total energy radiated: 100 billion tons of TNT per second
The Sun’s Structure
Where the energy is created.
Nuclear reactions burn every second about 700 million tons of hydrogen into helium.
Where energy is transported by radiation.
Although the photons travel at the speed of light, they bounce so many times through the dense material that they use about a million years to escape the Sun.
Energy transported by convection (just like boiling soup) where heat is transported to the photosphere.
Dark areas (umbra, penumbra)
Strong magnetic fields
Inhibit energy transport from solar interior
Cooler areas, and therefore darker
The Sun’s Magnetic Field
The Sun is strongly affected by magnetic forces.
The red arrows show open magnetic field lines emerging from the poles.
The gray arrows represent solar wind particles which carry field lines with it.
The bright active regions have closed magnetic field lines (orange).
Solar Activity 1992-1999
The Solar Corona
The corona is the area just above the surface. While the surface is about 5,000o Celsius, the temperature in the corona reaches about 2 million degrees Celsius. What causes this rapid increase in tempera-ture is still one of the big mysteries in solar physics.
What is the Solar Wind?
A constant stream of particles flows from the Sun’s corona, with a temperature of about a million degrees and with a velocity of about450 km/s. The solar wind reaches out beyond Pluto's orbit (about 5900 million kilometers). The drawing shows how it pushes on and shapes the Earth’s magnetosphere (the dotted line).
The SOHO Mission
Joint program between the European Space Agency (ESA) and NASA.
An industry team led by Matra Marconi Space built SOHO in Europe. It’s instruments were provided by nine European and three U.S. Principle Investigators
ESA: responsible for SOHO’s procurement, integration, and testing
NASA: provided launch and mission operations (at Goddard Space Flight Center)
Solar Interior: What are its structure and dynamics?
Corona: Why does it exist and how is it heated?
Solar Wind: Where is it accelerated and how?
Unique Operations Mode
“Live” display of data on scientists’ workstations