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Chapter 6

# Astronomy 1021 Chapter Notes - Chapter 6: Kelvin, Flattening, Room Temperature

Department
Astronomy
Course Code
ASTR 1021
Professor
Chris Racknor
Chapter
6

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Chapter 6: Formation of the Solar System
Solar System and Telescopes
All 3 techniques used in study of solar system
oImaging
oSpectroscopy
oTiming
We majorly focus on the properties of small bodies such as asteroids and Kuiper Belt objects
Measuring Distances
If we know the radius of Earth and if we can measure parallax angle, we can use geometry to
calculate the distance to planets/suns
Measuring Sizes
With the aid of telescopes, we can measure the angular diameter of planets
Since we know the distance, we can calculate the diameter in km
Measuring Masses
Moons goes around planets, we measure angular distances and orbits and period, then will find
the mass of planet
We get density (what the planet is made of)
Hampered by location (earth/its orbit)
Cheaper; can be used long-term and upgraded
Lots of new objects still to find
Can study many objects
Can get closer to solar system objects
oBetter spatial resolution
oin situ measurements
Can bring back samples
Take a long time to build, launch, travel
Very expensive
Solar System
Consists of the Sun and:
o8 planets
o170+ known moons
o5+ dwarf planets
oBillions of smaller bodies
Asteroids, comets, Kuiper Belt Objects
We can find planets' patterns by comparing to each other
oProvide insights that can help understand Earth
find more resources at oneclass.com
find more resources at oneclass.com

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All planets orbits in the same direction
Most large moons orbit planets in the same direction (also the direction of the Sun's rotation)
Planets are tiny compared to distances between them
Question: Scale of the Solar System
How much bigger is the Earth-Sun distance compared to the Sun’s radius ?
The Sun
Mostly hydrogen and helium
Contains 99.9% of the solar system's mass
Converts 4 million tons of mass into energy each second
Mercury
Made of metal and rock, with a large iron core
Bit bigger than the Moon
Desolated, cratered
Long, tall, steep cliffs
Very hot and very cold: 425oC during day, -170oC at night
Venus
Nearly identical size to Earth
Surface hidden by clouds
Rotates clockwise
1 day on Venus = 243 days on Earth
Sunrise at west, sunset at east
Extreme greenhouse effect
o470oC day and night
find more resources at oneclass.com
find more resources at oneclass.com

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Earth
Has the only surface liquid water in the solar system
Has a large moon
Only place with life
Question: Earth in context
How do the extra-solar (around other stars) planets that we know about compare to Earth?
A. Most known extrasolar planets are less massive than Earth
B. Earth’s mass is about average
C. Most known extrasolar planets are more massive than Earth
D. All known extrasolar planets are more massive than Earth
Mars
A cold desert
Giant volcanoes, huge canyon, polar caps, more…
Water flowed in distant past
There are a number of active Mars missions
find more resources at oneclass.com
find more resources at oneclass.com