A. Solar Info
- Closest Star to the Earth
- An ordinary G2 star, one of more than 100 billion stars in our galaxy.
- Contains more than 99.8% of the total mass of the Solar ##System
- Greeks --> Helios. Romans --> Sol.
- The Sun: Description
- Diameter: 1,390,000km (109XEarth)
- Mass: 1.989 X 1030kg (333,000XE)
- Surface temp: 5800 K
- Core temp: 15,600,000 K
- Density: 1.41 g/mL
- Rotation: 25 - 36 Earth days
- Age: 4.5 b.y.
- On a spiral arm of the Milky Way
- Revolves around Galactic Center...
- Outer layers exhibit differential rotation:
- at the equator: every 25.4 days
- near the poles: 36 days
- Second Generation Star
- Mass -> Gravity -> Pressure ->
- Temperature = Thermonuclear Fusion
- (H --> He)
- 4.5 billion years ago
- 75% H and 25% He by mass
- 92.1% H and 7.8% He by No. of atoms
- Everything else ("metals") amounts to only 0.1%
- Radiative Zone
- Convective Zone
- Solar Flares
- Solar Prominences
- d<50,000mi, where magnetic field lines are concentrated and come out of photosphere
- Solar wind, Aurora, bad FM reception
- Pioneer 5 - USA Solar Monitor - (Mar 1959) Still in solar orbit.
- Pioneer 6 - USA Probe - 63.4 kg - (Dec 1965 – Present) Still active.
- Pioneer 7 - USA Probe - 63 kg - (Aug 1966 - ?) Recently turned off.
- Pioneer 8 - USA Probe - 63 kg - (Dec 1967 - Present) Still transmitting.
- Pioneer 9 - USA Solar Probe - 63 kg - (Nov 1968 - Mar 1987) still in solar orbit. Died on March 3, 1987.
- Skylab -USA -(May 26, 1973) First US space station, manned for 171 days during 1973 and 1974. Included the Apollo Telescope Mount (ATM), to take more than 150,000 images of the Sun. Abandoned in February 1974 and re-entered Earth's atmosphere in 1979.
- Explorer 49 - USA -328 kg -(June 1973)
- Helios 1 - USA & West Germany -370 kg -(Dec 1974) Still in solar orbit; came within 47 million kilometers of the Sun.
- Solar Maximum Mission -USA -(Feb 1980) Designed to observe solar flares. Suffered an on-orbit failure. Repaired by STS-41C in 1984. SMM collected data until Nov. 24, 1989, and re-entered on Dec 1989.
- Yohkoh - Japan/USA/England -(Aug 1991) Studied high-energy radiation from solar flares.
- Helios 2 - USA & West Germany -(Jan 1976) Came within 43 million kilometers of the Sun.
- Ulysses - USA & Europe - 370 kg - (Oct 1990) An International project to study the poles of the Sun and interstellar space near the poles. Used Jupiter as a gravity assist to swing out of the ecliptic plane.
- SOHO - Europe - (December 12, 1995) (Solar and Heliospheric Observatory) To study the Sun's internal structure. "Halo orbit" around the L1 Lagrange point --1.5 million km away from Earth where the gravitational pull of the Earth and Sun balance.
- Genesis - USA Solar Wind Sample Return -(July 2001) To collect samples of solar wind particles and return them to Earth.
B. Kepler's Laws of Planetary Motion
- Planets' orbits are Ellipses with the Sun at one focus.
- A line joining the planet and the Sun sweeps out equal areas in equal times.
- “The Harmonic Law.” The squares of the periods of the planets are proportional to the cubes of their semimajor axes
 Adventures while measuring the size of the Solar System
- Major Axis-
- Semi-major Axis-
- Minor Axis-
“a” affects width “b” affects height If a = b , then it is a .....
D. Day/Year Terminology
- Solar day-
- 1 Sidereal day = 23.9344696 hours
- Solar month-
- Solar Year?
- Sidereal Year-
- Calendar Reform- 360days, 365days, 365.25days, 365.249days, names of months, Leeson calendar
- Tilt of Earth from Ecliptic =
- Specific(?) dates-
- Effects on seasons...
- Southern hemisphere opposites...
F. Other Interactions
- Solar Flairs and Storms cause the Aurora, affect Satellites, Power Grids, and Radio Communication
- Precession of the Earth's Axis causes changes in seasons (Sahara was lush 5000 years ago).
- In 4 billion years, the Sun will change and life will no longer be possible on Earth.
Bibliography Edwards, Jonathan. "Sun." World Book Encyclopedia. NY: Collier International. 1972. Vol 18, p313.
Sagan, Carl. Comet. New York: Random House. 1985.
"Sun." Online. October 17, 2001. http://seds.lpl.arizona.edu/nineplanets/nineplanets/sol.html http://solarviews.com/eng/sun.htm http://www.stemproject.fsnet.co.uk/ http://www.angelfire.com/la2/splashpage