Astronomy 100-09 Exam 1 Fall 2022 Flashcards
What is the definition of science?
the process by which the physical universe is studied, and understood
What are the physical laws in order?
data, model, theory
What is equal to a kilo?
10^3 or 1,000
What is equal to mega?
10^6 or 1,000,000
What is equal to giga?
10^9 or 1,000,000,000
What is equal to centi?
10^-2 or 0.02
What is equal to micro?
10^-6 or 0.000001
What is an astronomical unit and what is the constant?
average distance between earth and sun, 1.496x10^8 km
What is a light year and what is the constant?
the distance that light travels in one year, 9.46x10^12, or 12 trillion miles
What is a parsec and what is the constant?
distance and which 1 AU subtends an angel of 1 second of arc ( 1”), 1 pc averages to 3.25 ly or 3.09x10^13 km
What is the definition of angular diameter?
how big an object looks, expressed as an angle
What is 1 degree equal in arcminutes?
60 arcminutes or 60’
What is 1 arcminute or 1’ equal to in arcseconds?
60 arcseconds or 60”
What is 1 degree equal in arcseconds?
3600” or 3600 arcseconds
what is the celestial sphere?
the sky that appears to our eyes as a large dome at the center, excludes sun, moon, and planets
What is diurnal motion?
apparent daily motion of all celestial objects from east to west. caused by earths rotation from west to east, includes rising and setting phenomena
What is annual motion?
apparent motion of the sun WRT the “ fixed” stars, over the course of a year. caused by earths revolution of the sun, gives rise to seasonal constellations
Does earth orbit clockwise or counter-clock wise?
counter-clock wise
Earth’s rotational axis is tilted by?
23.5%
What is the vernal equinox?
the intersection of the CELESTIAL EQUATOR
and the ECLIPTIC, at the ascending node (south to north); Sun
appears directly over Earth’s equator.
What is the Summer Solstice?
the maximum northern position of the Sun in
the sky; Sun stops moving south to north, continues moving
west to east, in its apparent annual motion. 23.5 degrees north the celestial equator
What is Autumnal Equinox?
the intersection of the CELESTIAL EQUATOR
and the ECLIPTIC, at the descending node (north to south); Sun
appears directly over Earth’s equator.
What is Winter Solstice?
the maximum southern position of the Sun in
the sky; Sun stops moving north to south, continues moving
west to east, in its apparent annual motion. 23.5 degrees south of the celestial equator.
Definition of solar day?
measured by apparent motion of Sun from noon to
noon. Equal to 24 hours 00 minutes.
Definition of Sidereal Day?
measured by the diurnal motion of the “fixed”
stars; from local meridian to local meridian. Equal to 23 hours 56 minutes, also known as earth’s true rotational period.
Definition of precession?
The slow, continuous, change in the orientation of Earth’s
rotational axis in space.
Definition of Diurnal Motion?
daily apparent motion from east to west caused
by Earth’s rotation
Definition of Lunation?
a monthly motion across the sky WRT the “fixed”
stars, from west to east. Caused by the Moon’s revolution around Earth. Apparent motion of on average 13 degrees per day (15 degrees = 1 hour)
⇒ Apparent diurnal period on average 24h 50m on average
Definition of Lunar Phases?
refers to the apparent shapes of the Moon in
Earth’s sky.
Definition of Lunar Cycle?
refers to the order in which the lunar phases
always occur.
What is a new moon?
Moon in same E-W direction as Sun. First Lunar phase
What is a waxing crescent?
Western limb visible; % increasing. Second lunar phase
What is first quarter?
Moon 90 degrees east of Sun. Third lunar phase
what is waxing gibbous?
More than half of disk visible; eastern
limb dark; % increasing. Fourth lunar phase
what is a full moon?
Moon 180 degrees from Sun. Fifth lunar phase
what is a wanning gibbous?
More than half of disk visible; western
limb dark; % decreasing. Sixth lunar phase
what is a third quarter?
Moon 90 degrees west of Sun. Seventh lunar phase
what is a waning crescent ?
Eastern limb visible; % decreasing. Eighth lunar phase
what is a Synodic Month?
period required to complete one cycle of
phases; new moon to new moon. Measured relative to sun. 29.5 days long.
what is a Sidereal Month?
Moon’s true orbital period around Earth. Measured relative to the fixed stars. 27.3 days long.
what is a Prograde Motion?
apparent “wandering” motion from west to
east WRT the “fixed” stars, over months and years,
“pro” meaning “forward” thus can be thought of as a planet’s
regular motion; aka Direct Motion
what is Retrograde Motion?
apparent “wandering” motion from east to
west WRT the “fixed” stars, over weeks and months,
“retro” meaning backwards
who is Galileo Galilei ?
1564-1642: in 1609 became the first
astronomer ever to use a telescope to make astronomical
observations
what are some of Galileo’s discoveries?
-The Milky Way is made of countless individual stars
* Presence of mountains and craters on the Moon
* “Ears” on Saturn
* Spots on the Sun
* Phases of Venus that are correlated with angular diameter
* Four largest moons of Jupiter (1610)
who is Johannes Kepler?
(1571-1630): mathematician and first
astrophysicist; a heliocentrist
what are the three laws of planetary motion?
- Kepler’s First Law: planetary orbits are ellipses with the sun
at one focus
2.Kepler’s Second Law: “Law of Equal Areas”
orbits sweep out equal areas in equal intervals of time
3.Kepler’s Third Law: “Harmonic Law”
P2 = a3
P = sidereal period (years) A = semi-major axis (AU)
what are newtons three laws of motion?
- body at rest, remains at rest and a body in motion moves in uniform motion (straight line &
constant speed) unless acted upon by a force - quantifies the relationship between
force, mass, and the resulting acceleration
3.for every force there is an equal, but
opposite force
what is universal law of gravitation?
Greater mass ⇒ stronger gravitational force
Greater distance ⇒ weaker gravitational force
what is Newton’s corollary to Kepler’s Third Law?
Newton’s corollary to Kepler’s Third Law provides
astronomers with the only way to measure the masses of
astronomical objects.
what makes up the solar system?
- The 8 known planets
- Their moons and rings
- Dwarf planets
- Kuiper Belt Objects
- Asteroids
- Comets
- Meteoroids
- The Sun
Terrestrial versus Jovian planets
- terrestrial planets are earth like, small in size and closest to the sun ( 4 planets)
-Jovian planets are Jupiter like, bigger in size 4 outer planets
Characteristics of Mercury
- heavily crater
- low mass = weak gravity
- no atmosphere
Characteristics of Venus
- most similar to earth on radius, mass, and distance from sun
- highly reflective clouds
- heavy atmospheric pressure
Characteristics of mars
- very thin atmosphere
- dry river beds
- filled with minerals
- frozen polar ice caps
Characteristics of Jovian Planets
- very large
-very massive - low density
- very gaseous ( liquid interiors )
- gas giants ( Jupiter and Saturn)
- ice giants ( Neptune and Uranus)
How many rings does the Jovian planets have?
Jupiter 4
Saturn 30
Uranus 13
Neptune 9*
