Chapter 4: Formation of the Solar System (Textbook Notes)
planet (3 definitions):
1) orbits the sun or another star 2) has enough mass so that its own gravitational attraction causes it to be essentially spherical, rather than being a large, irregular rock in space 3) has enough gravitational attraction to clear its neighborhood of other orbiting debris
what conditions need to be satisfied to be a dwarf planet?
1) orbits the sun or another star 2) has enough mass so that its own gravitational attraction causes it to be essentially spherical, rather than being a large, irregular rock in space [but not condition #3]
how many dwarf planets are there? name them.
5, Pluto, Ceres, Haumea, Makemake, and Eris
How many planets are in the solar system? name them.
8; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune
the solar system formed some ..... after the universe came into existence
9 billion years
hydrogen & helium account for what percentage of all observed atoms?
99.9% of all absorbed atoms (or, equivalently, 98% of observed mass)
late heavy bombardment (describe)
During this interval, a disproportionately large number of asteroids are theorized to have collided with the early terrestrial planets in the inner Solar System, including Mercury, Venus, Earth, and Mars.[2] [google]
what are the inner, four rocky planets?
Mercury, Venus, Earth, and Mars
A few million years after Jupiter formed, collisions of planetesimals led to the formation of a second rocky world, ___
Saturn
planetesimals (describe)
a minute planet; a body that could or did come together with many others under gravitation to form a planet.
asteroid (describe)
a piece of space debris composed primarily of rock & metal that is larger than 10m
comets (describe)
all debris that is a roughly equal mix of ice & rock
trans-Neptunian objects (TNOs) (describe)
all the objects that orbit the sun farther than Neptune (plutinos and plutoids are examples)
moon (or) natural satellite (describe)
an object orbiting a larger body that
how did the late heavy bombardment end?
asteroids were destroyed by either striking something, falling into the sun, or eventually being flung out of the inner solar system
the asteroid belt contains...
asteroids, meteoroids, and comets
Big Bang (describe)
astronomers believe that the universe about 13.8 billion years ago in a violent event called the Big Bang, which created not only all the matter and energy that exists but also space & time
metals (describe)
astronomers define this as all the elements in the universe other than hydrogen and helium`
Kuiper belt (describe)
billions of flying planetesimals were flung into a bagel-shaped volume beyond the orbit of neptune that is now called the kuiper belt
how do planets "clear their neighborhoods"?
by either pulling surronding debris onto themselves or, in some cases, flinging debris far away from their orbits
what is the largest asteroid?
ceres
gasses compromising open clusters (interstellar clouds) have high enough internal pressures to prevent them from....
collapsing together & forming stars (probably how the solar system was formed)
the fist heat and light emitted by our sun came from...
colliding gas, not from thermonuclear fusion, as it does today
the inner planets formed primarily from ____
collisions
The changing orbits of the giant planets spread ___ throughout out the solar system
debris
the asteroid belt is leftover ____
debris
while the planets matured, the sun....
developed
the solar nebula rotated faster and faster and eventually became a ___
disk (this motion had a flattening affect on it)
because the planets formed in a disk, they should all orbit in more or less the same plane as ____
earth
how long has earth existed, and how do we know this?
earth formed along with the rest of the solar system about 4.6 billion years ago. the age is determined from the amount of radioactive decay that has occurred on earth
Earth, the Moon, Mars, Venus, Mercury, and many smaller bodies in the solar system were formed from matter that had been....
enriched with the heavier elements and depleted in hydrogen and helium
small solar system body (SSSB) (describe)
everything in the solar system that is not a planet, dwarf planet, moon, or part of a ring system (i.e. the majority of asteroids, meteoroids, and comets)
the categories of the solar system objects have ____
evolved
during the 100 million years that the inner planets were completing their formation, the protosun was also....
evolving
what were the two long term effects Jupiter's inward migration had on our solar system?
first, it passed through what is now the asteroid belt and prevented a planet from ever forming in that region second, it had a similar influence on stirring up the debris in the vicinity of what is now Mar's orbit
the collisions of hundreds of Moon-sized planetesimals led to the existence of...
four rocky inner planets: Mercury, Venus, Earth, & Mars
most stars form from....
gas and dust inside such giant interstellar clouds
While jupiter and saturn are called ___ ____, Neptune and Uranus are called ___ ___
gas giants; ice giants
What shaped the young solar system?
gravity, rotation, collisions, & heat
Stars transform matter from lighter elements into _____ ones
heavier
The solar system contains ___ ___ formed from an earlier generation of stars
heavy elements
The Earth, Moon, Mars, Venus, Mercury and many other objects that orbit the sun are composed of.... and have little....
heavy elements (i.e. oxygen, silicon, aluminum, iron, carbon, and calcium; they have little hydrogen and helium
Kuiper belt objects (KBOs) (describe)
ice-rich comets
as occurs with all gases, the protosun's temperature ____ as it became denser
increased
the infalling debris from the giant planets led to the ....
late heavy bombardment
one of the conditions that allowed for the beginning of biological evolution was the prescense of ....
liquid water
asteroid belt (describe)
major reservoir of leftover rock and metal debris remaining in the inner solar system
Oort cloud (describe)
many more planetesimals were send out even further than the Kuiper belt, creating a spherical distribution of debris called the Oort cloud
stars also shed ___ into space
matter (how stars lose matter)
the gravitational effects of Jupiter and Saturn forced many planetesimals to become concentrated out beyond Saturn's orbit, leading to the formation of two more rocky planets ___ and ____
neptune & uranus
were the sun & planets among the first generation of objects created in the universe?
no. all matter and energy were created by the Big Bang. However, much of the material that exists in our solar system was processed inside stars that evolved before the solar system existed. The solar system formed billions of years after the Big Bang occurred.
planetary nebulae were so named not because... but because of....
not because they have any direct connection with real planets, but rather because they looked like planets in early, low resolution telescopes
thermonuclear fusion (aka fusion) (describe)
once stars form, gravity compresses the matter in their central cores so much that the hydrogen there is transformed into helium
solar system is made up of....
one star, our sun, and all the bodies that orbit it -- planets, moons, and various kinds of debris (called asteroids, comets, and meteoroids)
the orbits of the planets are ____
related
____ played a key role in the formation of the solar system
rotation
craters (describe)
scars that were created by a planet being impacted by another large body
the giant planets formed in ____
sequence
protoplanetary disks (describe)
similar disks of gas and dust surrounding other young stars
describe a supernovae event
so powerful that fusion occurs during these explosions, creating a variety of heavy elements (i.e. nickel, copper, silver, gold) which are also expelled from the star
The solar system formed 4.6 billion years ago from a swirling, disk-shaped cloud of gas, ice, and dust called the ___ _____
solar nebula
the formation of the solar system: vast, rotating cloud of gas and dust (_____ ____) begins to collapse -> ____ forms, begins to grow -> orbiting gas & dust form a ____. Heat from the protosun removes gases from the inner disk out to the "___ ____" -> _____ between dust particles created large debris, including Moon-sized bodies. The first planet to form _____, cleared the gas and dust in its orbit -> Saturn, Neptune, and Uranus formed, closer than they are today. Debris from outside the snow line spiraled inward. ___ ____ formed from the debris and orbiting moon-sized bodies -> Saturn, Neptune, and Uranus spiraled ___, with Neptune and Uranus changing places. Much debris was sent inward and far outward during this period, creating the ___ ___ and ___ ___
solar nebula protosun disk; "snow line" collisions; Jupiter terrestrial planets outward; kuiper belt and oort cloud
meteoroids (describe)
space debris smaller than asteroids and composed primarily of rock and metal
The outer layers of stars are expelled at different rates, ranging from continuous outflows called ____ ____ to the more energetic expulsion of gases called ___ ____ to spectacular detonations called _____
stellar winds, planetary nebulae, supernovae
Jupiter rotates because it formed from ___ ___ in the solar nebula. Just like all the other planets in our solar system rotate
swirling debris
Mercury, Venus, Earth & Mars are also referred to as ____ planets
terrestrial
planetesimal bodies led to the formation of the ___ ____
terrestrial planets
what is density?
the amount of mass of any substance within a given volume
orbital inclinations (describe)
the angles of the orbital planes of the other planets with respect to the ecliptic plane
"snow line" (describe)
the boundary beyond which these gases and ices of water, carbon dioxide, methane, and ammonia persisted ~ the outer solar system, beyond the snow line, had both dust and ice (including hydrogen and helium), while inside the snow line, such ices were vaporized by the protosun
accretion (describe)
the coming together of smaller pieces of matter to form larger ones
fragments of interstellar clouds can collapse under....
the influence of their own gravitational attraction
to find out more about the solar system's origins, astronomers study....
the leftover interplanetary debris: asteroids, meteoroids, and comets
resonance (describe)
the situation where the two periods of two orbits are related by whole numbers (because the resulting gravitational interactions between the two bodies reinforce each other)
how many stars are there in the solar system?
the sun is the only star in our solar system
what happened to the center of the protosun?
the temperature and pressure at the center continued to increase
planetary nebulae and supernovae leave only.....
tiny, dim, but in many cases very hot stellar cores, remnants of once mighty stars
how are interstellar stars formed?
when over time, enough gas and dust were emitted by enough stars
protosun (describe)
when the density, pressure, and temperature at the center of the nebula began to increase, producing a concentration of matter called the protosun
