1. Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4 Solar Physics it is a star has a radius of about 696,000 km composed of H and He emits large amount of mass and energy (about 4 x 10E33 erg/sec) “quite” sun radiates IR radiation (thermal) Surface temperature (approximately 4,600 K) is about 93 miles away from the Earth Also emits steady stream of protons and electrons Sun

2. Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4 Solar Physics Space environment and environmental effects in Earth orbit are due to the solar activities Sun releases “energy” in several forms Explosions causes “shock” waves Magnetic field causes disturbances Relative motion of the Earth, sun, and other bodies causes local changes (i.e. thermal)

3. Sun’s image during an eclipse The planets x-ray image Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4 Solar Physics Solar flare The sun

4. Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4 Solar atmospheric layers Photosphere Corona Chromospheres

5. Photosphere, the visible surface of the Sun Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4

6. Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4 Chromospheres, the layer of the solar atmosphere Located above the photosphere, but beneath the transition region and the corona. Hotter than photosphere, but not as hot as corona

7. Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4 Outer layer of the solar atmosphere. Consists of a highly rarefied gas with low density and a high temperature. Temperature is greater that 1,000,000 K. Visible to the naked eye during the solar eclipse. Corona

8. Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4 Solar Physics and its influence on the formation of the Earths atmosphere and near earth space environments will be covered by Prof. Dr. Yurdanur Tulunay

9. Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4 Electromagnetic Spectrum Solar Spectrum irradiance wavelength 0.5 1.0 1.5 2.0 IR UV visible Gamma rays10E22 Hz Xrays10E19 Hz UV VISIBLE10E14 IR Microwaves10E10 Hz RF10E4 Hz Utility Power50-60 Hz

10. Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4 Electromagnetic Spectrum Absorption and transmission in Earth’s atmosphere

11. Space Environment September 30,2003 H. Kirkici Istanbul Technical University Lecture-4 Questions?...