Unit 2 - Exploring the Solar System Flashcards
what did newton develop?
an explanation for planetary motion using the same laws that apply on earth, kepler’s law
what makes planets orbit in an elliptical circle and not continue in a straight line?
they have a force acting on them, the force of gravity from the sun, the centripetal force (The sun) pulls the planet towards the center of the circle
what are kepler’s three laws?
planets move around the sun in elliptical orbits, a planet sweeps out equal areas in equal time (moves faster closer to the sun), the square of the orbital period (T) is proportional to the cube of the average orbital radius (R)
what are newton’s three laws?
objects stay in motion/at rest unless there is a net force acting on it, force = mass x acceleration, every applied force has an equal and opposite force
explain newton’s third law with respect to the planets
the sun pulls on planets with gravity and the planets pull on the sun
why don’t satellites fall towards the earth? why do things orbit?
they have enough velocity so that they fall towards the earth at the same rate the earth curves
what is the centrifugal force?
force that pushes the object away from the center
how do we get to the force of gravity formula?
force of gravity is proportional to mass 1 and mass 2; force of gravity is inversely proportional to 1 over the radius of earth squared, so force of gravity is equal to the gravitational constant times mass 1 times mass 2 over radius of earth squared
acceleration due to gravity also called
gravitational field strength
what is the formula for acceleration due to gravity?
force of gravity over mass
what is the formula for centripetal acceleration?
ac = v^/r
what is required for something to accelerate faster?
more centripetal force, related to newton’s second law
kepler’s second law formula
r^3/t^ = gm/4pi^
define rotation
the spinning of an object around its axis
give an example of rotation
earth completes rotation around its axis in 24 hours
define revolution
the movement of one object around another (orbit)
give an example of revolution
earth completes a full revolution around the sun in 365.25 days
define orbital radius
average distance between the sun and the celestial object of interest
how do you explain an elliptical orbit?
eccentric
what kind of motion does the moon exhibit and what this means?
synchronous motion; means the same side of the moon is always facing earth
define synchronous motion
the rotational period is the same as the revolution
where is the moon on our moon phases?
to the right
moon phases starting from right going down with what it looks like
new (all dark), waning crescent (light on left corner), third quarter (light on left side), waning gibbous (dark on right corner), full (all light), waxing gibbous (dark on right corner), first quarter (dark on right half), waxing crescent (light on right corner)
define solar eclipse
the moon passes between the earth and the sun, the sun’s bright atmosphere (corona) can be seen, moon casts a shadow on earth
define lunar eclipse
when the earth passes between the moon and the sun, earth casts a shadow on the moon (appears red)
define force of gravity
a natural phenomenon by which physical bodies attract with a force proportional to their mass and inversely proportional to the square of their distances
explain how high tides and low tides are formed?
moon’s gravity pulls earth and its oceans towards it, this causes a bulge of water to form on the side of the earth facing the moon
what are high tides also called?
spring tides
what are low tides also called?
neap tides
what is the geocentric model of the solar system?
earth is the center of the solar system
who created the geocentric model of the solar system?
claudius ptolemy
who was ptolemy and what era did he live?
roman citizen living in egypt; BCE
careers of ptolemy
math, astronomer, geogropher, astrologer, poet
define heliocentric model of the solar system
describes the sun as the center of the solar system
who created the heliocentric model of the solar system?
nicholas copernicus
what era did copernicus live and what was he?
1400-1500, renaissance astronomer from poland
era and country of galiei
1500-1600, italian
careers of galilei
math, physics, astronomer, philosophy
what was galilei known as?
father of modern physics
who supported and popularized the heliocentric model of the solar system?
galileo galilei
degree earth rotates at from the earth-sun orbital plane
23.5
what causes seasons?
the earth’s tilt causes sun to shine on northern/southern hemisphere as the earth orbits around the sun
season when axis is pointed towards the sun on the left
winter south of equator, summer north of equator, sun shines directly on northern hemisphere, position of summer solstice for northern hemisphere
season when axis is away from the sun, directly in front of it
spring south of equator, fall north of equator, sun shines equally on both hemispheres, position of autumnal equinox for northern hemisphere
season when axis is pointed away from the sun on the right
summer south of equator, winter north of equator. sun shines on southern hemisphere, position of winter solstice for northern hemisphere
season when axis is pointed towards the sun, directly behind the sun
fall south of equator, spring north of equator, sun shines equally on northern and southern hemisphere, vernal equinox for northern hemisphere
summer solstice date and what it is
june 21st, longest day
autumnal solstice date and what it is
september 21st, 12 hours of daylight, first day of autumn
winter solstice date and what it is
december 21st, shortest day
vernal equinox and what it is
march 21st, 12 hours of day light, first day of spring
earth’s precession and what this causes for earth
the earth spins around an axis that wobbles like a slow spinning top, the wobble takes 26,000 years to complete, the north star is polaris, in 12 000 years the new north star will be vega star
if the rotation axis of the earth were perpendicular to the eciptic, would day and night be equally long?
yes
how do you measure true north?
measured from stars
why are true north and magnetic north different?
compass needle always points to magnetic north and it changes every day because it corresponds to earth’s magnetic field lines, difference is magnetic variation
why do the poles experience continuous day and night?
due to earth’s tilt, sun hits poles for 6 months at a time
in winter and summer at the north poles, how does the sun appear?
winter - sun sinks below the horizon, summer - sun rises at the north pole, reaching a max height on summer solstice
is the day length ever the same at the equator as at the north or south pole?
poles and equator have equal day lengths
why isn’t june 21st the hottest day since it’s the longest
sun has to melt the ice and warm the oceans before we feel the heat
3 factors that affect milkankovitch cycles and what do they do over time?
shape of earth’s orbit (Eccentricity), tilt of its axis (obliquity), direction of its axis (precession), over time they change
what do the 3 factors do to earth?
change the amount of solar energy reaching earth
what is perihelion
a planet’s closest approach to the sun
what is aphelion?
a planet’s furthest distance to the sun
formula to calculate eccentricity
aphelion - perihelion/aphelion + perihelion
when the eccentricity is greater than zero, what does this mean?
the sun is not in the center of the ellipse
cycle of earth’s eccentricity (shape of orbit)
100,000 year cycle
what does it mean in solar radiation when eccentricity is larger?
the greater the difference in solar radiation reaching earth at perihelion vs at aphelion
what does obliquity result in?
seasons
earth’s climate if obliquity is 0 degrees?
no difference in seasonal temperatures
cycle of obliquity for earth
40,000 year cycle
what does a larger obliquity mean?
larger difference in seasonal temperatures
what is precession caused by?
the gravitational effects of the sun and moon
what does precession cause?
hemisphere at perihelion (closest to the sun) has warm summers and cold winters, opposite hemisphere has cold summers and warm winters
how can we see based on milankovitch cycles that we have global warming?
we are outside our normal ranges, however milankovitch cycles do not account for greenhouse gases as the result of human activity
6 ways to classify things in our solar system
star, planet, dwarf planet, asteroid, comet, moon/natural satellite
define star
a fixed luminous point in the night sky that is a large, remote, incandescent body
example of a star in our solar system
sun
define planet
a celestial body moving in an elliptical orbit around a star
name our 8 planets in order from the sun
mercury, venus, earth, mars, jupiter, saturn, uranus, neptune
define dwarf planet
a celestial body resembling a small planet but lacking certain criteria that are required for it to be classified as such
give an example of a dwarf planet
pluto
define asteroid
a small rocky body orbiting the sun
give an example of an asteroid
ida
define a comet
a celestial object consisting of a nucleus of ice and dust, and when near the sun, a tail of gas and dust particles pointing away from the sun
give an example of a comet
halley
define moon/natural satellite
a celestial body in space that orbits around a larger body
give an example of a moon
titan
what is retrograde motion and what is it caused by?
planets we are passing by look as if they go backwards in orbit and look around
example of real retrograde motion
venus rotates on its axis in the opposite direction of every other planet
why does december have the longest days?
it takes more than 360 degrees for the sun to reach the same highest point in the sky as the earth rotates because the earth is also revolving around the sun so it takes more than 360 degrees for the sun to reach the same point, it takes approx 361 degrees and because we are closer to the sun at december in its perihelion, earth moves faster closer to the sun and earth has to rotate futher on its axis for sun to return to noontime position, it takes about 33 seconds extra (earth’s tilt and elliptical orbit)
define a solar day
the time it takes for the earth to rotate about its axis so the sun appears in the same position in the sky
define sidereal day
the time it takes for the earth to complete one rotation about its axis with respect to the fixed stars
difference between sidereal day and solar day
sidereal day is 4 minutes shorter
facts about mercury
smallest planet, drastic temperatures,
facts about venus
one of the hottest planets, blue
facts about mars
dust gives red colour, similar to earth
facts about jupiter
largest planet, many moons
facts about saturn
rings made of ice and rock
facts about uranus
orbits on side, methane makes it blue,
facts about neptune,
strong winds, cold
