The Moon: *July 20, 1969, Neil Armstrong( 1st person to set foot on the moon. (Now, 12 people so far.)
-We know moon’s age, composition, and a lot of its history from 400 kg of rock & soil samples from lunar landings. –Diameter ≈ distance from San Francisco to NY City. –Once had a molten surface, but cooled too fast for plate motion. –Bombarded by meteoroids. –This and volcanic activity filled basins w/ lava to produce thicker igneous crust. –Because it is too small to have atmosphere & w/out weather eroding agents = only meteoroid impacts. [pic]
Phases of the Moon: –Begins w/ new moon (darkness & Sun. moon, Earth are aligned w/ moon in b/w), waxing crescent (next 7 days), *waxing = increasing, first quarter (∠ b/w the sun, moon, & Earth = 90˚, half is sunlit), waxing gibbous (next week, we see more sunlit part) *gibbous = more than ½, full moon (sunlit side faces us squarely & moon is completely illuminated, the sun, Earth, and moon are lined up, w/ Earth in b/w) *Cycle reverses in 2 weeks & we see less and less of sunlit side. Waning gibbous, *waning = shrinking, last quarter, & waning crescent. (1 complete cycle ≈ 29.5 days)
Eclipses: Solar Eclipse: New moon is directly in front of the sun & moon’s shadow falls on parth of the Earth. *Total eclipse = when the sun disappears behind the moon & ends when it reappears on the other edge of moon. (≈ 3 or 3 mins. Max ≈ 7.5 mins.) –Darkness of it is not complete because of the bright corona that surrounds the sun.
Lunar Eclipe: Full moon passes into Earth’s shadow. (follows/lags a solar eclipse by 2 weeks. –When it is fully eclipsed, it is still visible & is reddish in color. **An eclipse requires EXACT alignment of the sun, Earth, and moon. (occurs only about twice per year)**
One Side of the Moon: –We always see the SAME side of the moon. –Moon spins quite slowly ≈ once every 27 days. (rate matched rate of revolution around Earth) *torque = a turning force w/ leverage –The moon aligns w/ the Earth’s gravitational field. (side nearer to Earth is gravitationally pulled more than other side)( If it’s axis doesn’t line up, a torque acts and therefor the moon lines up w/ Earth in its monthly forbit. **Only 1 hemisphere faces us. The Sun: *Our nearest star. –Every second, 4.5 milllion tons of mass in the sun converts to radiant energy, but a tiny fraction of this reaches earth. –The sun’s suface is a glowing 5800-kelvin plasma ≈ 500 km thick. *photosphere = sphere of light( On this surface, they are cool regions created by strong magnetic fields. (They appear as sunspots when viewed from Earth.) –They are 2x the size of Earth, seem to move around because of Sun’s rotation & last for about a week. (Often they cluster in groups.) –The sun’s atmosphere (above the photosphere) =10,000km thick transparent shell of plasma. *chromosphere = sphere of color –Beyond chromosphere, there are streamers & fliaments of outward-moving, high temperature plasmawhich are curvec by the sun’s magnetic field. *corona = outermost region of Sun’s atmosphere **Hotter than Sun’s surface. –Several million km from the sun until it merges into a hurricane of high-speed protons & electrons. (the solar wind)(powers aurora borealis on Earth & produces tails of comets & influences “space weather” (has serious impact on electronic & communications of satellites.)
–Sun spins slowly on axis, more of a fluid so diffent lattitudes spin @ different rates. –Equatorial regions spin oce in 25 days, but higher latitudes take up to 36 days. (distorts the solar magnetic fields(sunspots) –Max/Min = 11 years.
Formation of the Solar System: Universe formed in 5 billion yesrs ago. (hydrogen & helium)( Solar system formed 10 billion years later. *All elements beyond H & He formed in the cores of stars. –Exploding stars produce pressure waves & compress the gas pockets. –Gravitational potential energy becomes thermal energy & clump’s center becomes hotter. –Disk cooles(birth of…