Download ADVANCED PLACEMENT CHEMISTRY

Beverly Hills  Environmental Science
Scientific Method Astronomy
STUDY
1  Science and Scientific Method
Science: The systematic study of the natural world through
observation and experimentation. The systematic study
method is the Scientific Method.
Scientific Method: The steps that Galileo used in his
experiments has been adopted by scientists. It is one
logical approach to solving scientific problems
1. Observation: Using senses to obtain information.
2. Hypothesis: Proposed explanation for observations.
An educated guess.
If independent variable then dependent variable.
3. Experimentation: Test your hypothesis.
4. Data Analysis: look at and study your experimental
results.
5. Conclusion: Is your hypothesis true or false?
6. Replication: Can other researchers repeat your
experiment and get the same results (confirm it).
Experimental Design: How do we set up a good
experiment?
1. Control Group: Group that is left untreated,
unchanged. It is the “normal” or “original” state or
situation.
2. Experimental Group: Group that is exposed to a
varying amount of the control group variable. We
change the control group’s amount.
3. Independent variable: Factor that you are testing.
What you put IN to check what comes out.
4. Dependent Variable: The factor the you measure,
your output. It DEPENDS on your INdependent
variable. It is what comes OUT of the experiment.
2  Astronomy: History
Astronomy: the science that studies the universe. It deals
with the properties and laws of objects in space.
Galaxies: The universe is made up of billions of galaxies. Our
galaxy is the Milky Way.
Solar Systems: Galaxies are made up of solar systems that
have stars at their centers. Our star is called The Sun. There
are 8 planets surrounding our Sun.
Greeks Astronomers: The golden age of astronomy was in
Greece from 600 BC to 150 BC.
Aristotle: concluded Earth is round since earth casts a
curved shadow on the moon (right conclusion but wrong
reasoning). Believed in Geocentric model (earth-centered).
Eratosthenes: Determined the size of the earth (diameter
and circumference) using shadows cast at Syrene and
Alexandria.
Hipparchus: Determined the length of one year to within a
few minutes.
Aristarchus: Believed in a Heliocentric model (sun-centered)
of solar system, but no on believed him.
Ptolemy: Summarized the golden age of Greek astronomy in
a 13-volume set in 141 AD. Believed in a geocentric model
that went unchallenged for 1,300 years!
Geo-centric Model
Modern (European) Astronomers: Used natural laws and
the scientific method to study astronomy instead of religious
GUIDE
and philosophical views.
Copernicus (Poland): First major astronomer in 13
centuries. Earth is also a planet like the other five known
planets. Earth is rotating too, which explains day and night
and motion of the stars better. Proposed a heliocentric
model.
Brahe (Danish): Built an observatory and designed
instruments. Made precise measurements of mars, other
planets, and other heavenly bodies for 20 years. Hired Kepler
(German) as assistant for last year before he died.
Kepler (German): Brahe’s data did not fit circular orbit for
Mars. Kepler’s Three Laws of Planetary Morion: 1)
Discovered Mars has an elliptical orbit. All 8 planets do too.
2) Planets sweep out equal areas in equal time intervals. 3)
Square of the Period (T2) is equal to the cube of the distance
to the sun (d3). T2=d3; d in astronomical units (1 A.U. = 150
million kilometers); T in years.
F G
mA mB
d2
Galileo (Italian): Discovered the telescope; Jupiter’s four
moons; that planets are circular disks; that Venus has phases
like our moons; that the surface of our moon is not smooth;
the Sun’s sunspots.
Newton (British): Wanted to find
 the force that kept planets
from moving in a straight line. He found that the force is
universal gravitation. He also discovered the concept of
inertia.
 Every body in the universe attracts every other
body.
 This force of attraction is proportional to their
masses and inversely proportional to the square of
the distance between their centers of mass.
Ocean Tides caused by gravitational pull on earth by the
moon.
3  Astronomy: Earth-Moon-Sun
Three Motions of the Earth: Earth has two main motions:
rotation and revolution; and one minor motion: precession.
Rotation has to do with the earth’s spinning on our axis in one
day. Revolution determines our trip around the sun in one
year. Precession is the slow rotation of the axis that takes
26,000 years to complete. The axis points to Polaris (north
star). In the year 14,000 it will point towards the star Vega.
Rotation=Day: Mean solar day (relative to sun) = 24 hours
Sidereal day (relative to fixed star) = 23 hr, 56 min, 4 s.
Revolution=Year: Speed = 107,000 km/hr ; distance to sun =
150 million km; perihelion = 147 million km (Jan3); aphelion =
152 million km (July4). Peri=around, near; apo=away
Earth’s Tilt: The earth is tilted 23.5°. This creates the
seasons.
Moon’s Orbit: Perigee = moon closest to earth; apogee =
moon farthest from earth.
Moon Month: Siderial Month = 27.322 (to fixed star)
Synodic Month 29.531 days (to sun). 2.21 day diff!
Solar Eclipse: Moon passes between Sun and Earth to block
sunlight. Umbra=total solar eclipse; penumbra=partial solar
eclipse
Beverly Hills  Environmental Science
Scientific Method Astronomy
STUDY
GUIDE
3  Astronomy: Sun-Earth-Moon System
Phases of the Moon:
Maria: Ancient beds of basaltic lava, originated when asteroids
punctured the lunar surface, letting magma bleed out. Maria comes
from the Latin word for sea (mare). They appear as dark colored
seas and inspired early astronomers to see them possibly as seas.
Highlands: Elevated and densely pitted, light-colored areas of the
moon’s surface undisturbed by the large crater impacts that
created the marias.
Rille: A long channel associated with lunar maria. A rille looks
similar to a valley or a trench.
Moon Month: Siderial Month = 27.322 (to fixed star)
Synodic Month 29.531 days (to sun). 2.21 day diff!
Solar Eclipse: Moon passes between Sun and Earth to block
sunlight. Umbra=total solar eclipse; penumbra=partial solar
eclipse
4  Our Solar System
Lunar Eclipse: Earth passes between Sun and Moon to block
sunlight. Umbra=total lunar eclipse; penumbra=partial lunar
eclipse. Umbra=shade; pene=almost+umbra=shade
The Sun: The Sun is at the center of our Solar System. The Sun
makes up 99.85% of the mass of the solar system; 70% H2 and 28%
He; less than 2% is metals. The sun converts the hydrogen to helium
over time. Temp: 5,800K at the surface, 15,600,000K at core!
Terrestrial planets are planets that are small and rocky—Mercury,
Venus, Earth, and Mars. Latin terra – earth (aka Inner or Rocky)
Jovian planets are the huge gas giants—Jupiter, Saturn, Uranus, and
Neptune. The God Jove = Jupiter. **Pluto does not fit into either the
Jovian or the terrestrial category. It is not considered a planet
anymore. (aka Outer, Giant, or Gaseous planets)
Moon History: The most widely accepted model for the origin of
the moon is that when the solar system was forming, a body the
size of Mars impacted Earth. The resulting debris was ejected
into space, began orbiting around Earth, and eventually united to
form the moon.
Nebular theory: Sun and planets formed from a rotating disk of dust
and gases. A nebula is a cloud of gas and/or dust in space.
Moon Atmosphere: The moon has no atmosphere to protect it
from asteroid collisions. Earth has few craters because of our
atmosphere. The surface has many craters. Craters are formed
from either 1) a depression at the summit of a volcano or 2) a
depression produced by a meteorite impact.
Rays are any of a system of bright, elongated streaks of ejecta,
sometimes associated with a crater on the moon.
Lunar Rigolith: A thin, gray layer on the surface of the moon,
consisting of loosely compacted material. A.K.A. Moon dust.
Property of Craig Mosher, BHHS