Ast101 All Lectures (Final Practise)
Understand the relative size of the Earth to the rest of the Solar System. -
correct answer ✔ ✔ ← Sun is 109x diameter of earth
← Terrestrial Planets: Mercury ⅓ the diameter, Venus is just barely
smaller than Earth, Mars is around ½ the diameter
← Jovian Planets: Saturn 9.5x the diameter, Jupiter 11x the diameter,
Uranus 4x the diameter, Neptune 4x the diameter (just slightly smaller
than Uranus)
← Earth is largest Terrestrial planet, but far smaller than Jovian
Planets/The Sun (Also bigger than all asteroids and moons in the solar
system)
Correctly use the terms Planet - correct answer ✔ ✔ ← Planet: A
moderately large object that orbits a star and shines primarily by
reflecting light from its star. According to the current definition, an
object can be considered a planet only if it (1) orbits a star, (2) is large
enough for its own gravity to make it round, and (3) has cleared most
other objects from its orbital path. An object that meets the first two
criteria but has not cleared its orbital path, like pluto, is designated a
dwarf planet.
,Correctly use the term Moon - correct answer ✔ ✔ ← Moon: An
object that orbits a planet. The term satellite is also used more generally
to refer to any object orbiting another object.
Correctly use the term Star - correct answer ✔ ✔ ← Star: A large,
glowing ball of gas that generates heat and light through nuclear fusion
in its core. Our sun is a star.
Correctly use the term solar System - correct answer ✔ ✔ ← Solar
System: The Sun and all the material that orbits it, including planets,
dwarf planets, and small solar system bodies. Although the term solar
system technically refers only to our own solar system (solar means "of
the Sun"), it is often applied to other star systems as well.
Correctly use the term Galaxy - correct answer ✔ ✔ ← Galaxy: A
great island of stars in space, all held together by gravity and orbiting a
common center, with a total mass equivalent to millions, billions, or
even trillions of stars.
Understand the number of stars in a galaxy and the number of galaxies
in the observable universe. - correct answer ✔ ✔ ← 100 Billion Stars
in our galaxy, 1 trillion galaxies in the observable universe
← 10 dump trucks full of sand, each grain is a galaxy. Within each grain
imagine another entire dumptruck where each grain of sand is a star.
,Correctly use astronomical distance units such Astronomical Units (AU)
and light years (ly) - correct answer ✔ ✔ ← Astronomical Units
(AU): The average distance between Earth and the Sun, which is about
150 million km. More technically, 1 AU is the length of the semimajor
axis of Earth's orbit.
← Light Years (ly): The distance that light can travel in 1 year, which is
about 10 trillion km
State the approximate sizes of important astronomical structures, such as
planets, stars, solar systems, and galaxies, in AU and ly - correct answer
✔ ✔ ← Sun/Planets: So small that AU and ly don't really make
sense (Less than 0.1 for all of them)
← Our Solar System: 100,000 AU in diameter (Numbers vary widely),
1.5 ly
← Galaxy: 6 billion AU, 100,000 ly
Understand the relationship between astronomical distance and lookback
time - correct answer ✔ ✔ ← Because of the way light travels, we
are seeing objects as they appeared when the light is coming from them.
(Ex an object we see that is 100 ly away appears to us now as it looked
100 years ago) Lookback time = Time elapsed between when we detect
light on Earth and when it was originally emitted by the source
, Correctly describe the shape and major motions (orbit, rotation) of
objects in the solar system - correct answer ✔ ✔ ← All planets have
nearly circular orbits going around the same direction in nearly the same
plane. Most large moons orbit their planets in this same direction, which
is also the direction of the Sun's rotation. (Same for asteroids)
← Planets farther out orbit slower
Recognise the major patterns of motion in the solar system and, later,
relate these to its formation mechanism - correct answer ✔ ✔ ←
Planets of motion among large bodies: The Sun, planets, and large
moons generally orbit and rotate in a very organised way.
← Two major types of planets: The eight planets divided clearly into
two groups: the small, rocky planets that are close together and close to
the Sun, and the large, gas-rich planets that are farther apart and farther
from the Sun.
← Asteroids and comets: Between and beyond the planets, vast numbers
of asteroids and comets orbit the Sun; some are large enough to qualify
as dwarf planets. The locations, orbits, and compositions of these
asteroids and comets follow distinct patterns.
← Exceptions to the rules: The generally orderly solar system also has
some notable exceptions. For example, among the inner planets only
Earth has a large moon, and Uranus is tipped on its side. A successful
theory must make allowances for such exceptions even as it explains the
general rules.
Understand the relative size of the Earth to the rest of the Solar System. -
correct answer ✔ ✔ ← Sun is 109x diameter of earth
← Terrestrial Planets: Mercury ⅓ the diameter, Venus is just barely
smaller than Earth, Mars is around ½ the diameter
← Jovian Planets: Saturn 9.5x the diameter, Jupiter 11x the diameter,
Uranus 4x the diameter, Neptune 4x the diameter (just slightly smaller
than Uranus)
← Earth is largest Terrestrial planet, but far smaller than Jovian
Planets/The Sun (Also bigger than all asteroids and moons in the solar
system)
Correctly use the terms Planet - correct answer ✔ ✔ ← Planet: A
moderately large object that orbits a star and shines primarily by
reflecting light from its star. According to the current definition, an
object can be considered a planet only if it (1) orbits a star, (2) is large
enough for its own gravity to make it round, and (3) has cleared most
other objects from its orbital path. An object that meets the first two
criteria but has not cleared its orbital path, like pluto, is designated a
dwarf planet.
,Correctly use the term Moon - correct answer ✔ ✔ ← Moon: An
object that orbits a planet. The term satellite is also used more generally
to refer to any object orbiting another object.
Correctly use the term Star - correct answer ✔ ✔ ← Star: A large,
glowing ball of gas that generates heat and light through nuclear fusion
in its core. Our sun is a star.
Correctly use the term solar System - correct answer ✔ ✔ ← Solar
System: The Sun and all the material that orbits it, including planets,
dwarf planets, and small solar system bodies. Although the term solar
system technically refers only to our own solar system (solar means "of
the Sun"), it is often applied to other star systems as well.
Correctly use the term Galaxy - correct answer ✔ ✔ ← Galaxy: A
great island of stars in space, all held together by gravity and orbiting a
common center, with a total mass equivalent to millions, billions, or
even trillions of stars.
Understand the number of stars in a galaxy and the number of galaxies
in the observable universe. - correct answer ✔ ✔ ← 100 Billion Stars
in our galaxy, 1 trillion galaxies in the observable universe
← 10 dump trucks full of sand, each grain is a galaxy. Within each grain
imagine another entire dumptruck where each grain of sand is a star.
,Correctly use astronomical distance units such Astronomical Units (AU)
and light years (ly) - correct answer ✔ ✔ ← Astronomical Units
(AU): The average distance between Earth and the Sun, which is about
150 million km. More technically, 1 AU is the length of the semimajor
axis of Earth's orbit.
← Light Years (ly): The distance that light can travel in 1 year, which is
about 10 trillion km
State the approximate sizes of important astronomical structures, such as
planets, stars, solar systems, and galaxies, in AU and ly - correct answer
✔ ✔ ← Sun/Planets: So small that AU and ly don't really make
sense (Less than 0.1 for all of them)
← Our Solar System: 100,000 AU in diameter (Numbers vary widely),
1.5 ly
← Galaxy: 6 billion AU, 100,000 ly
Understand the relationship between astronomical distance and lookback
time - correct answer ✔ ✔ ← Because of the way light travels, we
are seeing objects as they appeared when the light is coming from them.
(Ex an object we see that is 100 ly away appears to us now as it looked
100 years ago) Lookback time = Time elapsed between when we detect
light on Earth and when it was originally emitted by the source
, Correctly describe the shape and major motions (orbit, rotation) of
objects in the solar system - correct answer ✔ ✔ ← All planets have
nearly circular orbits going around the same direction in nearly the same
plane. Most large moons orbit their planets in this same direction, which
is also the direction of the Sun's rotation. (Same for asteroids)
← Planets farther out orbit slower
Recognise the major patterns of motion in the solar system and, later,
relate these to its formation mechanism - correct answer ✔ ✔ ←
Planets of motion among large bodies: The Sun, planets, and large
moons generally orbit and rotate in a very organised way.
← Two major types of planets: The eight planets divided clearly into
two groups: the small, rocky planets that are close together and close to
the Sun, and the large, gas-rich planets that are farther apart and farther
from the Sun.
← Asteroids and comets: Between and beyond the planets, vast numbers
of asteroids and comets orbit the Sun; some are large enough to qualify
as dwarf planets. The locations, orbits, and compositions of these
asteroids and comets follow distinct patterns.
← Exceptions to the rules: The generally orderly solar system also has
some notable exceptions. For example, among the inner planets only
Earth has a large moon, and Uranus is tipped on its side. A successful
theory must make allowances for such exceptions even as it explains the
general rules.
