lecture 1 Flashcards
NATS 1530 lecture 1 material
What is a super-moon?
why, what does it look like, characteristics, frequency
- occurs when the moon is at/near perigee
- occurs because the moon orbits the earth in an elliptical orbit
- appears 30% brighter bc it is closer to earth
- size differences are not visible with the naked eye
- occurs ~3-4 times a year; occured 4 months consecutively this year (2024)
Perigee vs. Apogee
Perigee
- closest approach of the moon to earth
- looks larger and 30% brighter
Apogee
- furthest approach of the moon to earth
- looks smaller and dimmer
What is the moon Illusion?
Moon appears larger when it is cloe to familliar terrestiral objects (trees, houses, horizon)
- moon’s apparent size does not change during the night
What is a blue moon?
why, what does it look like, who came up with it
- when its the second full moon of the month
- moon cycle is 29.5 days; technically a month could have a full moon on the 1st and 30th (except february)
- when its the 3rd of 4 full moons of a season
- does not actually apear blue
- Farmgers Almanac came up with the term in the 1930s
What does NASA/Boeing want to copy SpaceX on? What ship is NASA attempting to do this with?
their “space taxi” idea
- bringing astronauts and regular people into low eath orbit (LEO) (300-500km above earths surface)
- space x does this with their spaceship dragon
starliner is the ship NASA wants to use for taxi-ing
What is Starliners “crewed mission”?
what happened, why it happened, why NASA did what they did,
- first half was successful; flew to international space station (ISS)
- during docking of ISS, starliners 28 thrusters behaved abnormally
- astronauts had to manually dock spacecraft
- could not return to earth; everything must be 100% perfect to go back through earths atmosphere + thrusters are necesary to return
- starliners crew are to remain in the ISS for ~8 months until dragon return them
- starliner will return to earth human-less
- NASA deemed thrusters not reliable enough for human use during re-entry
- NASA is very cautious with their astronatuats after accidentely killing 14 while ignoring the advice of their engineers.
What is the importance of the night sky?
historical importance
survival
- crops and hunting were reliant on the position of the sun/stars and celestial motions for best times to crop/hunt
- prepare for seasons by observing where the stars are in the sky (winter = gathering food)
time keeping
- relied on where, and thus when the sun and stars aligned
- led to the development of the calender
Name some early observations made about space.
earlier centuries
- planet means wanderer
- humanity realized that some lights in the night sky moved with a periodic motion (planets)
- planets shine by reflecting light from our sun (16th century)
- mercury-saturn were the first known planets
- sun is self luminous (produces vast amounts of energy); planets are not
- indigenous peoples invented many things related to astronomy (el caracol:observatory, majorville cairin and medicine wheel, stone hedge)
Horizon vs Zenith vs Nadir
Horizon
- where the sky meets the ground
Zenith
- the point directly overhead
Nadir
- the point directly below
Earths rotation and diurnal motion
what degree does earth rotate on, and what is diurnal motion
- Earth spins on an axis of 23.5 degrees
- diurnal motion is the daily motion of the heavens moving east to west; coincides with earths axis of rotation
___ in the east, ___ in the west
fill in the blank
Everything (stars, moon, planets, sun) rises in the east, sets in the west
- everything rotates on the north/south pole; keave a camera pointing to the stars, leave it, and the stars will apear more west than before
What does star motion apear to be at different latitudes: North pole, Equator, Intermediate latitudes (everywhere else)
imagine standing at each point; remember how earth rotates at poles
North/South pole
- stars circle zenith; do not rise or set
- 90 degrees latitude
Equator
- celestial poles on horizon; stars rise up and down
- 0 degrees latitiude
Intermediate Latitudes
- stars rise and set at an angle
- celestial poles between overhead and horizon
the stars dont move, planets do
What is the celestial sphere?
what it is, how they were named
- the celestial sphere is an imaginary construct that allows us to place the sun, moon, and stars on a surface that surounds the earth; we are the observers
- sphere is divided into 88 sections (constelltions) containing all the stars within the celestial sphere
- indigenous culture named them after familiar animals/things; aspects of their culture
Earths motions
moon, sun, earth, why we dont feel dizzy
moon
- spins 1500km/h around earth
earth
- moves around the sun at 30km/s
- moves through milky way at 225km/s
- earth is moving not the sun
we dont get dizzy because
- gravity
- earth is moving at a constant speed; we just move with it without noticing any changes
Zodiacs
how many, where they got their names
there are techincally 13 (ophiuchus), but only 12 are recognized
- they go by different indigenous names
How do seasons occur?
hemisphere tipping; If earth didnt have a 23.5 degree tilt, seasons would not exist
- when it is summer, your hemisphere tilts towards the sun; gives your area a more direct path of the suns energy
How do sun rays affect seasons?
in summer, sun appears high in the sky, and its rays hit your hemisphere more directly; sun is above horizon for longer periods of time (more heat and sunlight)
- the rays spread less as it hits more directly
- suns path is focused on northern hemisphere
in winter, sun is lower in the sky, and hits your hemisphere less directly; sun rays are spread out over a wider areas, less concentrated heat
- spreading more
- suns path is focused on northern hemisphere
in spring/fall, sun is ‘middle’ of the sky, and hits your hemisphere an equal amount as the other
- spread equally
- suns path is focused on equator
north and south pole are always cold because the sun is least concentrated there
moon cycle
how long, what it is
lunar phasing cycle is ~29.5 days
eliptical orbit (apogee and perigee)
phases of the moon
8 phases
- New moon (complete darkness)
- waxing cresent (3/4 darkness)
- first quarter (1/2 darkness)
- waxing gibbous (1/4 darkness)
- full moon (no darkness)
- waning gibbous (1/4 darkness)
- third quarter (1/2 darkness)
- waning cresent (3/4 darkness)
we cant see the moon fully illuminated at all times because of our perspective on earth
Why do we only see one side of the moon?
the moon rotates; allowing us to only see about 50% of it at any time
- other side does get illuminated by the sun; no “dark side” of the moon
it rotates on its axis the same rate at which it rotates the earth; most stable this way
- gives the moon 14.5 days of sun and dark
also because of earths gravitational pull
- ocea tides arise because of the moon and the earth rotating under that influence
Lunar vs. Solar eclipse
lunar eclipse
- moons orbit is on a 5 degree incline
- occurs every ~6 months; takes hours to complete
- sun -> earth -> moon
- earth blocks all light to moon
- can be partial
- blood moon - total lunar eclipse; moon passing through the center of the earths shadow which gives an orange/red hue
- the light is diffused through earths atmosphere; long wavelength radiation passing through earths atmosphere reaching the moon
solar eclipse
- sun -> moon -> earth
- moon creates shadow on the earth which blocks suns light for ~7 minutes, twice a year at any given location on earth
- can be partial; moon is at apogee, cant block all of suns light (called annular eclipse)
- animals will get confused thinking its sunset
- we can feel temperature drop temporarily
why is the Geocentric model wrong?
who created it, why its wrong, what is right?
created by Ptolemy
- was able to predict where planets would be (mercury, venus, mars, jupiter, and saturn)
it states that planets orbit earth, because earth didnt feel like it was moving; earth was considered the centre of the universe
earth is not geocentric its actually heliocentric
- sun is the center, not the earth
Heliocentric universe
what is it, who developed it
- sun is the center, while other planets orbit the sun
- motion is governed by the motion of the sun
copernicus developed the heliocentric model in the 15th century
- he believed the geocentric model was wrong
- beleived sun was giving energy to earth; didnt make sense if earth was the center
he only published this theory on his deathbed
Who was Kepler and Brahe?
they were astronomers of the 17th century
Brahe
- measured positions of objects in the sky
Kepler
- a mathematician who used his math to decide which model of the universe was correct
- verified the tycho crater, largest crater on the moon
- created 3 laws (keplers laws) about space
What were Keplers 3 laws?
explain them
Keplers 1st law
- verified circular orbits were incorrect
- planets orbited the sun in elliptical paths (squashed circle
- circumference of a circle is defined by radius
- eccentricity, e, for an elipse is its measure of how far from circular the ellipse is (squashed meter)
- sun is the focus of the ellipse
Keplers 2nd law; law of equal areas
- planets move at different speeds around the sun; farther from sun = slower speeds
- closest point to the sun for a planet is called Parigelion
- farthest point to the sun for a planet is called Aphelion
- straight line joining a planet sweeps out equal areas in space in equal intervals of time (conservation of angular momentum)
Keplers 3rd law
- the orbital period around the sun of any object was related to its distance from the sun
- an astronomical unit (AU) is the average distance between earth and sun; further than the distance = more than one AU, less than the distance = less than 1 au
- the square (^2) of a planets orbital period is proprtional to the cube of the semimajor axis of its orbit
- if you define the semi major axis of the objects orbital ellipse in units related to the average distance of the earth from the sun, than its orbital period in years was (p^2 = a^3)
how to solve Keplers 3rd law equation?
(p^2 = a^3)
P = years
a = astronomical units
