It's still cloudy/rainy/snowy. We only saw blue sky on Dec 30, but not enough to watch stars.
MasteringAstronomy is working now. The first thing is to get a sense of distance.
I also learned the moon and some new words on the web.
Apogee Perigee Avarage
0.405mkm 0.363mkm 0.38mkm
Aphelion Perihelion Avarage
152mkm 147mkm 150mkm 1.5 x 10^8km--- AU
circumference diameter radius
sidereal -- a real full orbit synodic -- a full phase (month)
27.3 29.5 (days)
AU -- Astronomical Unit
light year -- 3 x 10^5km/s x3600 x 24 x 365 = 9460800000000km = 10 ^ 13 km
Mars orbit -- 1.5 AU 220mkm
Jupiter -- 5.2 AU
Saturn -- 10 AU
Uranus -- 20 AU
Neptune -- 30 AU
Pluto -- 40 AU
Alpha Centauri -- 4.1 x 10^13 km
Earth Radius -- 0.0063mkm 6,374km
Earth circuference -- 6,374 x 2 x 3.14 = 40,000 km
Sun Radius -- 0.7mkm 700,000km
milky way -- 10^5 light year in diameter, contains 100billion stars 10^11
local group -- 3 x 10^6 ly across, 40 galaxies
andromada is 2.5 x 10^6 ly
Local supercluster -- 10^8 ly across
observable universe is 15 x 10^9 ly
light emitted from outside of obserable universe has no time to reach us yet.
radius --> radii
Facts:
5 month get to the moon if drive a car 100km/hour
8 hour to the moon use fastest spaceship 50,000km/h
2 year to Jupitor use this spaceship
10 months to Mars
100,000 years to Alpha Centauri
8 min for the sun light to reach earth
5 hours for the sun light to reach pluto
