THE SUN The Sun is the most prominent feature in our solar system. It is the largest object and contains approximately 98% of the total solar system mass. One hundred and nine Earths would be required to fit across the Sun's disk, and its interior could hold over 1.3 million Earths. The Sun's outer visible layer is called the photosphere and has a temperature of 6,000°C (11,000°F). This layer has a mottled appearance due to the turbulent eruptions of energy at the surface. Solar energy is created deep within the core of the Sun. It is here that the temperature (15,000,000° C; 27,000,000° F) and pressure (340 billion times Earth's air pressure at sea level) is so intense that nuclear reactions take place. This reaction causes four protons or hydrogen nuclei to fuse together to form one alpha particle or helium nucleus. The alpha particle is about .7 percent less massive than the four protons. The difference in mass is expelled as energy and is carried to the surface of the Sun, through a process known as convection, where it is released as light and heat. Energy generated in the Sun's core takes a million years to reach its surface. Every second 700 million tons of hydrogen are converted into helium ashes. In the process 5 million tons of pure energy is released; therefore, as time goes on the Sun is becoming lighter. The chromosphere is above the photosphere. Solar energy passes through this region on its way out from the center of the Sun. Faculae and flares arise in the chromosphere. Faculae are bright luminous hydrogen clouds which form above regions where sunspots are about to form. Flares are bright filaments of hot gas emerging from sunspot regions. Sunspots are dark depressions on the photosphere with a typical temperature of 4,000°C (7,000°F). The corona is the outer part of the Sun's atmosphere. It is in this region that prominences appears. Prominences are immense clouds of glowing gas that erupt from the upper chromosphere. The outer region of the corona stretches far into space and consists of particles traveling slowly away from the Sun. The corona can only be seen during total solar eclipses. The Sun appears to have been active for 4.6 billion years and has enough fuel to go on for another five billion years or so. At the end of its life, the Sun will start to fuse helium into heavier elements and begin to swell up, ultimately growing so large that it will swallow the Earth. After a billion years as a red giant, it will suddenly collapse into awhite dwarf -- the final end product of a star like ours. It may take a trillion years to cool off completely. International Spacecraft Reveals Detailed Processes on the Sun NASA released on Wednesday never-before-seen images that show the sun's magnetic field is much more turbulent and dynamic than previously known. The international spacecraft Hinode, formerly known as Solar B, took the images. Hinode, Japanese for "sunrise," was launched Sept. 23, 2006, to study the sun's magnetic field and how its explosive energy propagates through the different layers of the solar atmosphere. The spacecraft's uninterrupted high-resolution observations of the sun will have an impact on solar physics comparable to the Hubble Space Telescope's impact on astronomy. "For the first time, we are now able to make out tiny granules of hot gas that rise and fall in the sun's magnetized atmosphere," said Dick Fisher, director of NASA's Heliophyics Division, Science Mission Directorate, Washington. "These images will open a new era of study on some of the sun's processes that effect Earth, astronauts, orbiting satellites and the solar system." Hinode's three primary instruments, the Solar Optical Telescope, the X-ray Telescope and the Extreme Ultraviolet Imaging Spectrometer, are observing the different layers of the sun. Studies focus on the solar atmosphere from the visible surface of the sun, known as the photosphere, to the corona, the outer atmosphere of the sun that extends outward into the solar system. "By coordinating the measurements of all three instruments, Hinode is showing how changes in the structure of the magnetic field and the release of magnetic energy in the low atmosphere spread outward through the corona and into interplanetary space to create space weather," said John Davis, project scientist from NASA's Marshall Space Flight Center, Huntsville, Ala. Space weather involves the production of energetic particles and emissions of electromagnetic radiation. These bursts of energy can black out long-distance communications over entire continents and disrupt the global navigational system. "Hinode images are revealing irrefutable evidence for the presence of turbulence-driven processes that are bringing magnetic fields, on all scales, to the sun's surface, resulting in an extremely dynamic chromosphere or gaseous envelope around the sun," said Alan Title, a corporate senior fellow at Lockheed Martin, Palo Alto, Calif., and consulting professor of physics at Stanford University, Stanford, Calif. Hinode is a collaborative mission led by the Japan Aerospace Exploration Agency and includes the European Space Agency and Britain's Particle Physics Astronomy Research Council. The National Astronomical Observatory of Japan, Tokyo, developed the Solar Optical Telescope, which provided the fine-scale structure views of the sun's lower atmosphere, and developed the X-ray Telescope in collaboration with the Smithsonian Astrophysical Observatory of Cambridge, Mass. The X-ray Telescope captured the rapid, time-sequenced images of explosive events in the sun's outer atmosphere. "By following the evolution of the solar structures that outline the magnetic field before, during and after these explosive events, we hope to find clear evidence to establish that magnetic reconnection is the underlying cause for this explosive activity," said Leon Golub of the Smithsonian Astrophysical Observatory. show the sun's magnetic field is much more turbulent and dynamic than previously known. The international spacecraft Hinode, formerly known as Solar B, took the images. Hinode, Japanese for "sunrise," was launched Sept. 23, 2006, to study the sun's magnetic field and how its explosive energy propagates through the different layers of the solar atmosphere. The spacecraft's uninterrupted high-resolution observations of the sun will have an impact on solar physics comparable to the Hubble Space Telescope's impact on astronomy. "For the first time, we are now able to make out tiny granules of hot gas that rise and fall in the sun's magnetized atmosphere," said Dick Fisher, director of NASA's Heliophyics Division, Science Mission Directorate, Washington. "These images will open a new era of study on some of the sun's processes that effect Earth, astronauts, orbiting satellites and the solar system." Hinode's three primary instruments, the Solar Optical Telescope, the X-ray Telescope and the Extreme Ultraviolet Imaging Spectrometer, are observing the different layers of the sun. Studies focus on the solar atmosphere from the visible surface of the sun, known as the photosphere, to the corona, the outer atmosphere of the sun that extends outward into the solar system. "By coordinating the measurements of all three instruments, Hinode is showing how changes in the structure of the magnetic field and the release of magnetic energy in the low atmosphere spread outward through the corona and into interplanetary space to create space weather," said John Davis, project scientist from NASA's Marshall Space Flight Center, Huntsville, Ala. Space weather involves the production of energetic particles and emissions of electromagnetic radiation. These bursts of energy can black out long-distance communications over entire continents and disrupt the global navigational system. "Hinode images are revealing irrefutable evidence for the presence of turbulence-driven processes that are bringing magnetic fields, on all scales, to the sun's surface, resulting in an extremely dynamic chromosphere or gaseous envelope around the sun," said Alan Title, a corporate senior fellow at Lockheed Martin, Palo Alto, Calif., and consulting professor of physics at Stanford University, Stanford, Calif. Hinode is a collaborative mission led by the Japan Aerospace Exploration Agency and includes the European Space Agency and Britain's Particle Physics Astronomy Research Council. The National Astronomical Observatory of Japan, Tokyo, developed the Solar Optical Telescope, which provided the fine-scale structure views of the sun's lower atmosphere, and developed the X-ray Telescope in collaboration with the Smithsonian Astrophysical Observatory of Cambridge, Mass. The X-ray Telescope captured the rapid, time-sequenced images of explosive events in the sun's outer atmosphere. "By following the evolution of the solar structures that outline the magnetic field before, during and after these explosive events, we hope to find clear evidence to establish that magnetic reconnection is the underlying cause for this explosive activity," said Leon Golub of the Smithsonian Astrophysical Observatory.
