Lecture 5 - Our Planetary System Flashcards
describe the composition of planets closer to sun and further from sun
closer to sun = more round and rocky
further from sun = more gaseous
how many major planets are there? what is the shape of their orbits?
8 major planets, nearly circular orbits
what are the 2 differences btwn Dwarf planets and major planets?
- Dwarf planets are smaller
- elliptical orbits
describe the rotation and orbits of all large bodies in our solar system
what is the exception?
all orbit and rotate in the SAME DIRECTION and nearly SAME PLANE
- counter clockwise from above
VENUS rotates in the opposite direction (clockwise from above)
does the moon orbit the same way as all large bodies?
yes
does the sun rotate the same way as all large bodies?
yes
what % of the solar system’s mass is the sun?
> 99.9%
where does most of the mass of the sun come from? what percent?
98% He and H by mass
is the sun gaseous or solid?
gaseous
how does temp and pressure change as you go deeper in the sun?
temp and pressure increase with depth
what process occurs in the sun?
nuclear fusion (H –> He)
how much H is converted to He? how much He is produced? where does the remaining mass go?
600 million tons of H converted to 596 million tons of He
the remaining 4 million tons converted to energy via E = mc^2
if the sun is losing so much H in fusion, how can the sun still survive?
loses lots of H but there is A LOT of H in the sun that can be used
describe the composition of mercury?
made of metal and rock with large IRON core
how do we know mercury has an iron core?
indicated by its high density
how does the size of mercury compare to other planets?
mercury is the smallest of the 8 major planets
what is a word to describe the environment of mercury? why?
DESOLATE –> no volcanoes, wind, rain
describe the atmosphere of mercury and 3 things that this indicates
MERCURY HAS NO ATMOSPHERE
- cannot dissolve asteroids or meteoroids
- cannot scatter sunlight or cause colour
- cannot insulate
what is the consequence of mercury not being able to dissolve asteroids or meteoroids?
lots of craters on mercury
what is the consequence of mercury not being able to scatter sunlight or cause colour?
can see stars during day time
what large structures are present on mercury? what does this indicate?
has large, steep cliffs
indicates past geological activity
describe the temperatures of mercury during the day and at night
425C during day
-150C during night (even though right next to sun)
describe the rotation pattern of mercury
tidal forces from the Sun have forced Mercury into an unusual rotation pattern
describe the size of venus
nearly identical size as Earth
describe venus rotation
rotates very slowly in opposite direction of Earth
are days on venus long or short?
days on venus are very long
which direction does the sun rise? which direction does the sun set?
the sun rises in the west, sets in the east
why is the surface of venus hidden? what allowed us to see it?
the surface of venus is hidden by dense clouds
could learn about surface once we used cloud-penetrating radar
describe the greenhouse effect on venus and why it occurs
Lots of heat trapped due to thick atmosphere containing CO2
small wavelengths from the sun can come in and are absorbed by rocks, then released as large wavelengths which cannot escape –> stay inside the atmosphere
what is the temp of venus at night and during day?
470C during day and night
3 reasons why Earth is a unique planet
- O2 to breathe
- O3 to shield surface from solar radiation
- abundant surface water to nurture life
why are there pleasant temperatures on Earth?
atmosphere contains just enough CO2 and water vapour to maintain a moderate greenhouse effect
