Space physics Flashcards
revision (27 cards)
Day and night (cause)
2 points
Earth’s rotation on its axis.
23.5 degree
Seasons ( 3 points)
Earth’s rotation-24 hours
Earth’s revolution-365 days.
The earth’s tilt causes the northern and southern hemispheres to receive infrared light from sun at different distances causing summer for the closer on and winter for the other one.
Moon (6-8 points)
No atmosphere.
Natural satellite.
Revolves around the earth.
Revolves on its own axis.
Both takes approx. a month.
The same side of the moon is facing the earth all the time. We don’t see the dark side of the moon.
Rises and sets due to earth’s rotation
When moon is in between the earth and sun we see new moon and when it on the other side where earth is in between we see the full moon.
Waxing and waning also happen.
Orbital speed
2 pi R/t
Solar system ( PLANETS) (6 points)
Inner planets- Mecury venus earth, mars.
Outer planets/ gas giants- Jupitar, saturn, uranus, neptune.
Separated by the asteroid belt.
Dwarf planet- Pluto
Also called trans-Neptunian objects.
Low density, made of ice and rocks.
Solar system origan( 3 points)
Sun- formed out of a nebula of gas and dust.
The particles rotating around it combined due to its high gravitational force to form an accretion disk and formed planets.
The solar system is said to have been formed during the same time.
Comets ( 5 points)
Approach the inner solar planets at random time intervals.
Elliptical orbits.
Density similar to the outer planets.
Dust, ice, methane.
When near the sun the gas gets blown backwards forming a head and tail (which is facing away from the sun)
Asteriods
In the asteroid belt.
Different sizes.
The mass is not large enough for them to become planets.
They fall
on earth as meteors.
The largest one is Ceres- Mass is large but not large enough to remove the gas around it.
Elliptical orbit
Non-circular orbits.
Low speed when away from sun, high speed when close to sun.
Accretion model evidence
The approx. age of earth found using the radioactive mineral rocks.
The rocks bought on earth from the moon.
The planets all rotate in the same direction and on almost the same plane.
It is said that the previous explosions mixed with the interstellar hydrogen and made our sun a second-generation star.
Why are planets near sun rocky.
As sun grew in size it became the particles like hydrogen, helium, water and methane were not heavy enough to stay near the sun in solid state.
That’s why the inner planets are denser, rocky and they have less mass as only 1% of the mass of the nebula was due to rocks.
The outer planets are light as they are gaseous and 99% of the nebula’s mass in concentrate into them.
Sun still has 99% of the solar system’s mass and so can hold the planets in place.
Gravity, distance and mass
Gravity is directly proportional to mass.
Gravity is inversely proportional to distance.
Planets ( inner)
Distance ∝ planet’s year.
Distance ∝ 1/ speed
distance ∝ 1/ temperature
1 exception- Venus which has a higher temp than mercury due to the carbon trapping heat into its atmosphere.
Mercury- No athmosphere so the temp differs during the day.
Mars- Neighbor to earth. Has seasons due to 24 degree axis longer than earth. Thin CO2 athmosphere.
Jupiter- Largest planet. Noted for its giant red spot.
Saturn- Rings of ice. Athmosphere similar to jupiter with methane, hydrogen, helium, ammonia.
Uranus and Neptune- Cold, methane and ammonia in atmosphere. Multiple moons and rings.
Can keep gas near them due to the large gravity due to their mass.
Pluto- Smaller than planets. Frozen atmosphere of methane and nitrogen. Largest moon in Charon out of the 5 due to the formed when 2 dwarf planet collided.
The brown cap of Charon contains organic molecules which can be used for evolution on earth.
Planets ( outer)
Jupiter- Largest planet. Noted for its giant red spot.
Saturn- Rings of ice. Athmosphere similar to jupiter with methane, hydrogen, helium, ammonia.
Uranus and Neptune- Cold, methane and ammonia in atmosphere. Multiple moons and rings.
Can keep gas near them due to the large gravity due to their mass.
Pluto- Smaller than planets. Frozen atmosphere of methane and nitrogen. Largest moon in Charon out of the 5 due to the formed when 2 dwarf planet collided.
The brown cap of Charon contains organic molecules which can be used for evolution on earth.
The sun ( 3 points)
Medium sized star. Infrared, visible light and UV.
Nuclear fusion
Stars life cycle ( LIGHT MASS)
A nebula becomes a protostar due to the gravitational force,
As temp rises in protostar the potential energy turns into kinetic and a star is born as nuclear fusion starts.
a protostar becomes a stable star when
the inward force of gravitational attraction
is balanced by an outward force due to the
high temperature in the center of the star
When hydrogen finishes it becomes unstable. The fusion decreases ad so the cores becomes hotter and starts using the leftover hydrogen even faster.
Becomes a red giant.
Core heats us turning helium into carbon.
Red giant collapses under its own gravity and the outer layer is released. It becomes a planetary nebula but still glows and becomes a white dwarf. Eventually the white dwarf looses its light and becomes black dwarf which is only theoretically possible as the universe is not old enough.
Star high mass
Becomes a red super giant when unstable and turns helium into carbon.
Then turns carbon into oxygen nitrogen and then iron.
The red giant becomes supernova when an explosion happens. The star brightens and temp becomes high to fuse into even heavier metals.
These materials are in the space for other stars to power them.
It becomes wither a dense neutron star or a black hole it the gravitational force is high enough.
Universe expanding
Proven through red shift.
The more the distance, the more the wavelength.
Doppler effect- When sound approaches you it seems high pitched.
This also supports the big bang theory.
It is said that the universe started from a dense dot of matter and expanded.
It the expansion keeps happening it is predicted that the invisible mass of universe can be high enough to make it collapse.
CMBR
Cosmic microwave background radiation.
From the big bang.
In the atmosphere. It was initially BCBR but now has shifted to MBR.
Hubble’s constant
V= H* d
The speed to the distance of recession bare a constant ratio.
The more the distance the faster the speed.
Hubble’s constant is the rate of expansion of universe.
1/ H = age of universe.
Gravitational field strength
Know that the strength of the gravitational field
(a) at the surface of a planet depends on the
mass of the planet
(b) around a planet decreases as the distance
from the planet increases
Light year
9.5 * 10^15 m
Distance not time.
Galaxies
galaxies are each made up of many billions
of stars
(b) the Sun is a star in the galaxy known as the
Milky Way
(c) other stars that make up the Milky Way are
much further away from the Earth than the
Sun is from the Earth
(d) astronomical distances can be measured
in light-years, where one light-year is the
distance travelled in (the vacuum of) space
by light in one year
Milky way
diameter of the Milky Way is approximately
100000 light-years
