Planets Exam #1
What is the relative lifespan of stars as a function of mass?
.16-1.0: 1 trillion-10 billion, 2.5-16: 1 billion-10 million, 16-40: 10 million-1 million
What is an astronomical unit (AU) and the what is the general distance of the planets from the Sun in these units?
1 AU = the distance from the sun to the earth; Mercury: .39 AU, Mars: 1.5 AU, Earth: 1 AU, Jupiter: 5 AU, Venus: .72AU, Asteroid Belt: 2-3.5 AU, Saturn 10 AU, Uranus: 19 AU, Neptune: 30 AU, Pluto 30-50 AU
What are the two forces that maintain a force balance within a normally operating star?
1. Gravity works to collapse a star. 2. Fusion in the core creates an outward pressure that works to expand the star.
What are the elements that can be fused in the core of a low-mass star like our sun?
1. Hydrogen fuses into helium 2. Helium fuses into beryllium 3. Helium and beryllium 4. Helium and Beryllium fuse into carbon. 5. Helium and carbon fuse into oxygen
The 5 stages of the Solar Nebula
1. The solar nebula consisted of hydrogen, helium, and microscopic dust grains. 2. A disturbance caused the solar nebula to slowly contract and rotate. 3. The solar nebula assumed a flat, disk shape with the protosun at the center. 4. Inner planets began to form metallic and rocky substances 5. Larger outer planets began forming from fragments and ices
What can supernovas create that fusion in core of stars cannot?
1. They spread massive amounts of elements into the surrounding regions where they can become components of new solar systems. 2. High supernova pressures cause the fusion of elements heavier than iron that cannot otherwise be fused within stars.
What is the approximate size of a celestial body for it to have experienced differentiation?
30+km
How much of the mass of the planets in our solar system resides in Jupiter?
70%
How much of the solar system's mass resides in the Sun?
99%
Which celestial bodies follow Kepler's laws?
All bodies of the Universe.
What are the basic properties of elliptical orbits and what different values of eccentricity means?
All the planets move in elliptical orbits, with the sun at one focus; The different values of eccentricity = the ratio of the distance from the center to the foci and the distance from the center to the foci and the distance from the center to the vertices.
What happens to the temperature of the core of the collapsing star and what is the effect on the outer regions of that star?
As the core contracts it heats up. The extra heat causes the outer regions of the star to greatly expand and cool. Cooler temperatures cause the star's light to shift to the redder part of the spectrum (red giant)
Why is Mercury's orbit more eccentric than the other terrestrial planets?
Because Mercury is the closest planet to the sun.
Why did Uranus and Neptune not grow as big as Jupiter and Saturn?
Because Uranus and Neptune did not grow fast enough to attract enough hydrogen and helium before it was blown out of the solar nebula.
Why does our moon create a perfect eclipse of the sun?
Because it is exactly the right size and the right distance from the earth
Why is the spin axis of most planets tilted relative to the ecliptic plane?
Because planet orbits are elliptical not circular.
Why do the giant planets have shorter days than terrestrial planets?
Because they are bigger.
Why did the gas giants have to form within 3-10 M from the birth of the sun?
Because they had to hold onto a lot of hydrogen and helium to get to the size they are now before the gases were blown away by the solar wind.
What are the types of meteorites that come from undifferentiated asteroids?
Chondritic Meteorites
What are the differences between chondritic and achondritic meteorites?
Chondritic meteorties: They have chondrules because they have not been altered by heat since their formation; Achondritic: They contain no chondrules because they have been melted by high temperatures which caused them to flow and mix.
What does it mean for a celestial body to be differentiated?
Differentiation is the process of melting and stratification of layers by density within a body. Lighter elements like silicon rose to form a rocky mantle and crust and the dense elements like iron sank into the center forming an iron core.
What is at the center of Aristotle's universe?
Earth
What is the type of nebula that are comprised of hot hydrogen ions (H+) and glow?
Emission Nebula
What remains the only way to fuse helium and create heat and light in the modern universe?
For fusion to occur in the center of stars
What happens when Helium gets used up in the core of a low-mass star?
Fusion shuts down and the star begins the slow process of collapsing
What is the relative angular velocity of Earth's satellites based on their orbital distance?
GEO-3km/s, Lageos-5.5km/s, HST-7.5km/s, ISS-7.5km/s.
What was the major breakthrough that allowed Kepler to explain the orbits of celestial bodies better than previous models?
He determined that the motions of the planets cannot be explained by circular orbits, he then said that the planets orbited the sun in ellipses and created three laws that described this motion.
What was Copernicus' great contribution to science?
He placed the sun at the center of the universe, called the heliocentric model.
How did Ptolemy explain the retrograde motion of Mars?
He used epicycles to explain the retrograde motion of mars in an earth-centered universe.
What is the difference in characteristics between hydrogen ions (H+) and molecular hydrogen (H2)?
Hydrogen ions have no electron: they are very hot and emit light. Molecular Hydrogen is two Hydrogen atoms, each with an electron. they are cool and do not emit light.
What are the three most abundant elements in the original solar nebula?
Hydrogen, Helium, Oxygen
What was the material available in the solar system that allowed the giant planets to grow big?
Ice
What is the heaviest element that can be fused in the core of a high-mass star?
Iron
What are possible consequences of the Grand Tack?
It caused a lot of objects to be thrown out of the young solar system.
What is a solar nebula?
It is a circumstellar disc of gas and dust that encircle new stars.
What is orbital resonance?
It is when a planets orbit becomes unstable due to two or more bodies orbiting at multiples of a common period causing them to come close together at regular time intervals.
Where was the Lafayette meteorite found and where did it originate?
It was found in a drawer and it is from a 1.3 billion year old lava flow.
What is the fate of our sun?
It will begin to collapse, shrink into a white dwarf, outgas its outer layers and become a red giant
What happens if you launch a rocket with very little angular velocity?
It will just fall back to earth.
What happens if you launch a rocket with a tremendous amount of angular velocity?
It will launch you into a safe orbit that will last forever.
How did the metallic asteroid Psyche form?
It would be part of the core of a much larger body that was smashed up by a collision
What is the relative size of the cores of the giant planets compared to Earth?
Jupiter: 12-45, Saturn: 9-22, Uranus: .25-1, Neptune: .5-1.5
How was Neptune discovered?
Kepler's laws could not fully explain the orbit of Uranus, leading a mathematician to propose the position and mass of an unknown planet. Neptune was discovered on the first night of searching in 1846.
What are the theories of why Mercury has an overly large core?
Mercury was assembled from mostly metal-rich building blocks and thus never has a large mantle; A giant impact blew off most of Mercury's mantle, Mercury's outer layers were vaporized by a hot young sun
What is the order in distance from the sun of the objects in our solar system?
Mercury, Venus, Earth, Mars, Ceres, Asteroid Belt, Jupiter, Saturn, Comets, Uranus, Neptune, Pluto, Kuiper Belt Objects, Eris
Where are stars born?
Nebulas
Is there actually cold, solid ice within the ice giants?
No, water, ammonia, and methane are referred to as ices even though they aren't solid.
What is the proper order of accretion?
Planetesimals- Accretion of chondrules through electrostatic attraction led to planetesimals up 10s of km in diameter; Protoplanets: Planetesimals became large enough to be gravitationally attracted to each other and collided to form protoplanets up to 100s of km in diameter; Planets- Gravitational attraction protoplanets led them to collide to become planets 1000s of km across.
Why does Pluto have such a highly eccentric orbit?
Pluto's orbit is highly eccentric because it is in an orbital resonance with the much larger Neptune meaning that these planets regularly interact gravitationally.
Which parameters influences the time it takes a planet to orbit the sun?
Semimajor axis
What are planetary nebula?
Small gas clouds of ionized hydrogen with low mass elements like carbon and oxygen
What is the primary source of most current nebula?
Supernova remnants spread out and combine for form nebulas.
Where do low mass stars acquire their heaviest elements?
Supernovas
How does temperature, density, and material available to build planets varies as a function of distance from the sun in the solar nebula?
Temperature and density of gas and dust in the solar nebula decreased with distance from the sun. the material available to build planets with increases with distance from the sun.
Where did the first Helium atoms originate?
The Big Bang
What is the motion of Jupiter and Saturn during the Grand Tack?
The Grand Tack Theory predicts that after Jupiter and Saturn grew to be gas giants, they moved toward the sun, then much further away to their present positions.
How is the chemistry of the sun determined?
The absorption spectrum shows the chemistry of the sun; absorption lines reveals what elements are present, and the thickness of the line reveals the element abundances.
How does the angular velocity of a rotating solar nebula varies with distance from the star?
The angular velocity of a rotating solar nebula is fastest closest to the star (smallest orbital radius) and slowest away from the star
Where do the atoms in your body originate?
The atoms in our bodies are made from the remnants of stars.
Which orbital parameters of a moon can be used to determine the mass of a planet?
The balance between gravity and centrifugal forces that control a moons orbit can be used to measure the mass of a planet.
What are chondrules?
The building blocks of the solar system: all planets, moons, and asteroids by combining them
What happens to the force of gravity when objects get closer?
The closer the objects the greater the gravitational force.
What is the likely composition of the asteroids and comets based on their location relative to the ice line?
The composition of objects in the asteroid belt is mostly rock and metal; The composition of objects in the Kuiper belt is an even mixture of ice, metal, and rock.
What is the principle of the conservation of angular momentum and its main consequence?
The conservation of angular momentum causes the clumps to spin more rapidly as they contract.
How did the conservation of angular momentum influence the spin of the planets?
The conservation of angular momentum dictates that a smaller radius leads to faster rotations; means that they will spin in the same direction that they orbit and about an axis perpendicular to the ecliptic.
What is the fate of the largest stars?
The core condense into a black hole and outer regions explode as a supernova
Where is the iceline located?
The iceline is located just inside Jupiters orbit.
How long did it take for the Solar nebula to transform into the Solar System we see today?
The solar system took a few hundred years to evolve into how it appears today.
Which terrestrial bodies don't have iron cores?
They all have iron cores.
What is a hot Jupiter?
They are gas giants similar in size to Jupiter but orbiting very close to their stars (well within Mercury's orbit) and are thus very hot.
Where are meteorites most easily found and where do most of them originate?
They are most easily found on glaciers because they stand out; they are fragments of asteroids, the leftover bits of planet formation.
How were the egyptians able to make iron tools 2000 years before the iron age?
They got iron from meteorites.
Which are the terrestrial planets?
Venus, Mars, Earth, Mercury
What is the basic difference between volatiles and refractory elements/compounds?
Volatile Elements: Condense into ices at low temperatures-far from the sun; Refractories: Condense into rocks and metals at high temperatures-close to the sun.
What causes nebula clumps to contract into high density regions?
When a nebula is perturbed by a passing star or a shockwave from a supernova.
What causes a supernova?
When fusion stops in a massive star.
What does Kepler's second law imply about the speed of a planet when its orbit approaches the Sun?
When the planet is close to the sun, it moves faster (Stronger gravitational force) When it is farther away it moves slower (weaker gravitational force).
How do asteroids or planets obtain an iron core?
differentiation
What red giants become red?
low-mass sun sized stars