Astronomy 131- Chapter 19, Web Assign Homework Q&A.
How many Earths does it take to stretch across Jupiter?
11
If you are measuring U238 decay in a rock sample, and find that 2 half-lives have elapsed, how old is the rock?
9 billion years
How is the solar nebula theory supported by the motion of solar system bodies?
All of the below - All of the planets orbit the sun near the sun's equatorial plane. - All of the planets orbit in the same direction that the sun rotates. - Six out of seven planets rotate in the same direction as the sun. - Most moons orbit their planets in the same direction that the sun rotates.
How does the solar nebula theory account for the drastic differences between terrestrial and Jovian planets?
All of the below. -The temperature of the accretion disk was high close to the sun and low far from the sun. -Terrestrial planets formed closer to the sun and are thus made of high-density rocky materials. -Jovian planets are large and have high mass because they formed where both rocky and icy materials can condense. -Jovian planets captured nebular gas as they had stronger gravity fields and are located where gases move more slowly.
How did the solar nebula get cleared of material?
All of the below. The radiation pressure of sunlight pushed gas particles outward. The intense solar wind of the youthful sun pushed gas and dust outward. The planets swept up gas, dust, and small particles. Close gravitational encounters with Jovian planets ejected material outward.
How do asteroids and comets differ?
Comets contain ices
What is the difference between the processes of condensation and accretion?
Condensation is the building of larger particles one atom (or molecule) at a time, whereas accretion is the sticking together of larger particles.
Which planet orbits between Venus and Mars?
Earth
It takes 4 half-lives before 100 percent of a radioactive parent transmutes into its daughter element.
False
Which of the following accurately describes the differentiation process?
High-density materials sink toward the center and low-density materials rise toward the surface of a molten body.
(b) What are most craters in the solar system are caused by?
Impacts from Space
Which planet has the greatest radius?
Jupiter
According to the solar nebula theory, why are Jupiter and Saturn much more massive than Uranus and Neptune?
Jupiter and Saturn formed earlier and captured nebular gas before it was cleared out.
How does the solar nebula theory explain the formation of an asteroid belt between Mars and Jupiter rather than a planet at this location?
Jupiter formed early and its gravitational influence altered the orbits of nearby accreting planetesimals such that their collisions became destructive rather than constructive.
Why do we reject the formation of planets as proposed by Buffon (the passing star hypothesis)?
Material pulled out of the sun would be too hot to condense and planetary systems are common, whereas near star collisions are rare.
Radiometric dating of rock samples indicates that the solar system formed about 4.56 billion years ago. Which rock samples have this age?
Meteorites
12.5 percent of a parent element remains after about 4 billion years. Which of the 3 elements in this animation fits this description?
Potassium 40
Why is the dust disk around Epsilon Eridani shown here brighter than the star Epsilon Eridani at far infrared wavelengths?
The dust disk is cooler and has more surface area than its star.
What is the origin of the atoms of hydrogen, oxygen, and sodium in the perspiration that exits your body during an astronomy exam?
The hydrogen nuclei were produced a few minutes after the big bang event 13.7 billion years ago, and the oxygen and sodium nuclei were synthesized inside stars more than 4.6 billion years ago.
Potassium-40 decays to calcium-40 with a half-life of 1.3 billion years. Use this diagram to determine the age of a rock in which only 12.5% of its original potassium-40 remains.
The rock is 3.9 billion years old.
How do astronomers believe the sun came to have less angular momentum than its system of planets?
The solar wind mass outflow carries angular momentum away from the sun and the sun's magnetic field drags material out in the solar system, transferring angular momentum outward.
What was the major problem for the solar nebula hypothesis that was proposed by Pierre-Simon de Laplace?
The sun contains little of the angular momentum of the solar system.
(c) Why are there so many cratered surfaces in the solar system?
There was much debris left over from the formation of the planets and moons, and many collisions in the early solar system.
Which of the following is NOT a property associated with terrestrial planets?
They have low density.
Compare the two radial velocity curves shown here for the stars 51 Pegasi and Upsilon Andromedae. Why is the curve for Upsilon Andromedae more complex than that of 51 Pegasi?
Upsilon Andromedae has more than one planet.
How do we know that extrasolar planets are orbiting other stars?
We see a star's light dim as a planet passes in front of the star and detect alternating Doppler shifts in the spectra of some stars.
Where are most asteroids located?
between the orbits of Mars and Jupiter
(a) Where are craters are found?
most solid surfaces in the solar system
(a) What produced the iron in Earth's core?
some nuclear fusion in a massive star's core, mostly supernovae
(b) What produced the gold and silver in Earth's crust?
supernovae
Which of the following is the most likely major heat source that melted early formed planetesimals?
the decay of short-lived unstable isotopes
