Our Sun

But it is not part of a multiple star cluster! Our Sun – The Abnormal Star Fact – our Sun is a star Average in size Commonly called a “Yellow Dwarf”, the Sun is actually white when viewed from space Middle Age for a star But it is not part of a multiple star cluster!

Anatomy of the Sun Chromosphere

TABLE 16.1 The Standard Solar Model REGION INNER RADIUS TEMPERATURE DENSITY DEFINING PROPERTIES (km) (K) (kg/m3) Core 0  15,000,000 150,000 Energy generated by nuclear fusion Radiation zone 200,000  7,000,000 15,000 Energy transported by electromagnetic radiation Convection zone 500,000  2,000,000 150 Energy carried by convection Photosphere 696,000* 5800 2  10-4 Electromagnetic radiation can escape—the part of the Sun we see Chromosphere 696,500* 4500 5  10-6 Cool lower atmosphere Transition zone 698,000* 8000 2  10-10 Rapid temperature increase Corona 706,000  1,000,000 10-12 Hot, low-density upper atmosphere Solar wind 10,000,000  10-23 Solar material escapes into space and flows outward through the solar system

Core In solar astronomy, the innermost part of the Sun is where energy, in the form of gamma ray photons, is generated by nuclear reactions. It takes anywhere between 10,000 to 170,000 years for these photons to make their way to the Sun’s surface.

Nuclear Fusion in the core The process by which multiple like-charged atomic nuclei join together to form a heavier nucleus.

In this reaction, hydrogen fuses to create helium and release energy. The proton–proton chain reaction dominates in stars the size of the Sun or smaller. In this reaction, hydrogen fuses to create helium and release energy. At the current rate of fusion, the Sun should continue to burn for another 5 billion years.

Radiative Zone An interior layer of the Sun, lying between the core and the convection zone. Photons travel outward by radiation in what is described as a “drunkard’s walk” as they are absorbed and then re-radiated over and over again in many different directions.

Convective Zone The layer of the Sun between the radiative zone and the photosphere where energy travels outward by convection. At this point, the gamma ray photons have been slowed down considerably and have been converted to lower frequency photons of light and heat.

Photosphere The visible surface of the Sun. It is a layer of gas that is heated enough to shine. It is the layer from which the light we actually see (with the human eye) is emitted. It is also the layer astronomer’s refer to as the Sun’s “surface.”

Chromosphere The layer above the photosphere and beneath the transition region and the corona. The chromosphere is hotter than the photosphere but not as hot as the corona.

Corona The outer layer of the sun. It looks like a halo and is visible during eclipses or from special telescopes. Extends about a million miles out into space.

Circulation in the Sun

Electromagnetic Radiation Energy created in the core radiates out through radiative (radiation) zone. Next, it moves from the core through the convective (convection) zone. Finally, it exits the Sun’s atmosphere.

Features of the Sun

Size comparison of Earth to a sunspot Sunspots appear as dark areas on the solar surface, contain strong magnetic fields that are constantly shifting. A moderate-sized sunspot is about as large as the Earth. Sunspots form and dissipate over periods of days or weeks. They occur when strong magnetic fields emerge through the solar surface and allow the area to cool slightly, from a background value of 6000 ° C down to about 4200 ° C; this area appears as a dark spot in contrast with the very bright photosphere of the sun. The rotation of these sunspots can be seen on the solar surface; they take about 27 days to make a complete rotation as seen from Earth. Sunspots Size comparison of Earth to a sunspot http://www.nasa.gov/mission_pages/sunearth/spaceweather/

11-Year Solar Cycle

Loops of cool plasma that link different parts of sunspots. Prominences Loops of cool plasma that link different parts of sunspots.

A solar prominence is vast and awesome in size in contrast to our little Earth. But the Earth is so far from the sun that these prominences pose no danger. Image via NASA

Huge, high-arching plasma columns Prominences Huge, high-arching plasma columns

Solar Flares May occur when prominences loop together, or sunspots move together. This produces a very violent eruption on the surface of the sun called a solar flare.

Coronal Mass Ejections CME’s Coronal Mass Ejections Large amounts of electrically charged gas suddenly ejected from the Sun’s corona.

CME’s During periods of sunspot maximum, CME’s can occur two or three times each day.

CME’s may appear as a bubble bursting out of the sun. http://www.mnn.com/earth-matters/space/stories/stunning-coronal-mass-ejection-erupts-from-sun-photo CME’s may appear as a bubble bursting out of the sun. They cause magnetic storms, which damage satellites, interfere with radio signals, and can damage electrical grids.

CME’s

CME’s – The Impact to Earth

The outflow of charged particles from the Sun’s corona. Solar Wind The outflow of charged particles from the Sun’s corona.

Aurora Borealis When CME’s, in the form of a solar wind, interact with our magnetosphere, they can produce the light show called an Aurora. The charged particles carried by the solar wind generate electric currents at the poles. These currents ionize gases in the atmosphere, which produce the lights.

Solar Storm Geomagnetic storm produced by solar flares, CME’s or coronal holes. Can affect satellites, communication and navigation systems, and electrical systems.

So then, how many light years is it from the Earth to the Sun? The Light year! The distance light travels in one year in a vacuum Light travels at 300,000 km/sec or 186,000 mi/sec 1 light year = 9,460,730,472,580.8 km (That is approximately 9.5 trillion kilometers or 5.9 trillion miles!!!) The distance from the Earth to the Sun is approximately 150,000,000 kilometers, or 93,000,000 miles. So then, how many light years is it from the Earth to the Sun?

How Long?

Solar Facts * Average distance from Earth: 93 million miles (150 million kilometers) * Radius: 418,000 miles (696,000 kilometers) * Mass: 1.99 x 1030 kilograms (330,000 Earth masses) * Makeup (by mass): 74% hydrogen, 25% helium, 1% other elements Average temperature: 5,800° Kelvin (surface), 15,500,000 ° Kelvin (core) * Average density: 1.41 grams per cm3 * Volume: 1.4 x 1027 cubic meters * Rotational period: 25 days (center) to 35 days (poles) * Distance from center of Milky Way: 25,000 light years * Orbital speed/period: 138 miles per second/200 million years

Hydrogen to Deuterium Deuterium to Helium-3 Helium-3 to Helium Nuclear Fusion Hydrogen to Deuterium Deuterium to Helium-3 Helium-3 to Helium

Anatomy of the Sun Corona - 1,700,000° C Chromosphere - 27,800° C Photosphere - 6,000° C Convective Zone Anatomy of the Sun To convert °C to °F °F = (°C X 9/5) + 32 Radiative Zone The CORE – 15,000,000° K

Nuclear Fusion The process by which multiple like-charged atomic nuclei join together to form a heavier nucleus.