P6 - space phy Flashcards

1
Q

how does the day work

A

-sun goes from east to west because of the earth’s rotation on its own axis

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2
Q

why can you see the moon at night

A

-it reflects the sun’s light

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3
Q

time taken for the moon to completely orbit around the earth

A

27.5 days

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4
Q

moon phases

A

-the moon’s orbit relative to the earths change, results in varying sunlight on different parts of the moon
-its a natural satellite of earth

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5
Q

time taken for the sun to completely orbit around the sun

A

365 days

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6
Q

seasons

A

-caused by the earth’s axis being tilted so different hemispheres receive varying amounts of sunlight = diff seasons
eg. summer & winter/ spring & autumn
-countries near the equator don’t have seasons as they receive direct sunlight all year
-the further the country from the equator, the more noticeable the season changes

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7
Q

order of the 8 planets from the Sun

A

-My Very Educated Mother Just Served Us Nachos
-Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
-rocky planets - Mercury, Venus, Earth, Mars
-gas giants - Jupiter, Saturn, Uranus, Neptune
-Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto have moons
-there’s an asteroid belt btw Mars & Jupiter

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8
Q

what orbits the Sun

A

-My Very Educated Mother Just Served Us Nachos
-dwarf planets - Pluto, Eris
-moons that orbit planets
-asteroids & meteoroids
-comets

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9
Q

what hold the celestial objects that the orbit the sun

A

-the sun’s gravitational pull
-greater the distance, the weaker the gravitational pull, slower orbital speed
-planets size affects the gravitational pull

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10
Q

heaviest object in the solar system

A

sun

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11
Q

what are asteroids & meteoroids

A

lumps of rock

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12
Q

what are comets

A

-at their farthest distance form the Sun, they’re made of frozen gas, rocks & dust
-as they move to the sun, they warm up & release a trail of gas & dust behind them
-orbits the sun in irregular paths

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13
Q

origins of the solar system

A

from a nebula, a large rotating cloud of gas & dust

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14
Q

accretion disk

A

flat rotating disk made by the spinning motion of the nebula

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15
Q

formation of planets

A

-planets were formed from the leftover material from the nebula that wasn’t drawn into the sun’s gravitational pull
-through accretion, smaller particles (gas & dust) were pulled tgt by gravity to form larger rocks = Rocky planets
-the heat of the sun pushed the lighter materials away from it to form Gas Giants

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16
Q

speed of light

A

3 x 10^8 meters per second

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17
Q

elliptical

A

the shape of the the orbits around the sun

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18
Q

eccentricity

A

how much the orbit path deviates from a perfect circle

19
Q

why are orbits elliptical

A

-at the start, the object travels past the sun due to its own momentum from the big bang
-When it gets close to the sun, the sun’s gravity pulls it
-the object speeds up & its kinetic energy carries it to its furthest point of the orbit
-the object then slows down & is pulled back to the sun again

20
Q

formula for orbital speed

A

2πr
——— = orbital speed (meter per second)
t
-orbital speed - speed of a planet in an orbit around the sun
-r - orbital radius - average distance from the planet to the sun
-t - orbital period - time taken for 1 complete orbit

21
Q

define star

A

ball of hot gas & plasma that is powered by nuclear fusion in its core

22
Q

define nuclear fusion

A

process of merging small nuclei into larger -nuclei to release energy
-needs high temp & pressure to start

23
Q

define neubla

A

-region of space containing gas (mostly hydrogen) & dust
-interstellar hydrogen clouds

24
Q

define protostar

A

dense hot ball or gas formed by a collapsed nebula

25
Q

define main sequence of stars

A

stable period of a star when it fuses hydrogen in its core

26
Q

why do stars look like they’re twinkling

A

their light passes through the moving air in the earth’s atmosphere

27
Q

milky way galaxy

A

-collections of stars, dust & gas that are held together by gravitational forces
-rotates around its center, 240 millions years for 1 turn
-all the stars inside it move at acl constant motion

28
Q

difference btw galaxy & universe

A

-galaxy - collections of stars, dust & gas that are held together by gravitational forces
-universe - collection of galaxies

29
Q

what is the closest star to earth

30
Q

stars

A

-nuclear fusion releases lots of energy & heats up the star
-very so they emit electromagnetic radiation, including visible light
-approximately spherical shaped
-size of star depends on the amount of material absorbed from the original nebula

31
Q

betelgeyse

A

-bigger than the sun
-star in the constellation of Orion
-cooler star than sun = reddish colour

32
Q

Procion B

A

-smaller than the sun
-star in the constellation of Canis Minor
-hotter than the sun = white colour

33
Q

why does the sun and other stars look different

A

-sun if the closest star to earth so it is seen as a bright sphere. Other stars are very far away so they look like faint points of light

34
Q

life cycle of a star about the size of the sun

A

-interstellar hydrogen clouds
-protostar
-main sequence
-red giant
-planetary nebula
-white dwaf

35
Q

dust

A

-fine particles of material that was formed in older stars
-these stars have exploded & scattered the dust in the Milky way

36
Q

life cycle of stars

A

-nebula collapses
-protostar
-star

37
Q

start of a protostar

A

-formed in a nebula
-nebula collapses when disturbed by stars or objects that pass by
-nebula collapses due to the gravitational forces between gas & dust particles pull them closer; as they get closer, they start to accelerate towards each other; nebula become dense
-gravitational forces compress the nebula into a sphere that is denser than the original nebula = protostar
-individual particles move very quickly = temp of the ball of gas is high
-some material from the nebula forms a disk that rotating around the protostar. The material may form planets

38
Q

protostar

A

-pressure & temp at core is higher than that on the surface
-gravitational forces pull the material inwards
-pressure from the hot core pulls the material outwards
-if protostar continues to absorb material, its size, gravitational force, pressure & temp increases

39
Q

protostar to star

A

-pressure in a protostar is eventually high enough for nuclear fusion reactions
-nuclear fusion releases lots of gamma radiation in its core which heats all material absorbed by the star. The heat increases the rate of reactions
-it is now hot enough to emit radiation of its surface
eg. fusion of 2 hydrogen nuclei = helium
-it starts the main sequence of its life

40
Q

main sequence of stars

A

-during this period, the star is fairly stable in its size & temp while fusion hydrogen in its core
-smaller the star, slower it uses up its hydrogen fuel & spend more time in the main sequence

41
Q

similarities btw protostar & star

A

-both are rotating balls of hot gas
-both pressure & temp increase towards the center

42
Q

differences btw protostar & star

A

-star has nuclear fusion, protostar doesn’t

43
Q

be careful of units