astro number 4 – Flashcards
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Observations in the infrared have detected dusty nebulae around T Tauri stars.
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true
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Outgassing is
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the release of gas from rocks as they are heated
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An extrasolar planet is
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a planet found orbiting around a star other than the sun
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The speed of the solar wind is approximately 400 km/s, and the distance from the sun to Saturn is 9.5 AU (1 AU = 1.5´108 km). How long does it take a particle in the solar wind to reach Saturn?
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about 41 days
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Condensation in the solar nebula probably led to the formation of
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a. icy grains beyond the present orbit of Jupiter. b. metallic grains near the present orbit of Mercury. c. silicate grains near the present orbit of Earth. d. all of the above (Correct)
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The original cloud from which the sun and planets formed had a composition rich in hydrogen and helium.
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true
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The oldest objects found so far in our solar system are Earth rocks that are 3.9 billion years old.
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false
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The planets all lie in nearly the same plane resulting in a disk-like structure for the solar system. This disk-like structure is believed to exist because
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the solar nebula from which the planets formed had a disk-like structure.
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Outgassing refers to the formation of an atmosphere by the attraction of gases from the surrounding nebula.
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false
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____ is the separation of material in a newly formed planet or asteroid according to density. This happens when the object becomes molten.
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Differentiation
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The Jovian problem refers to
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the apparently short period of time that disks exist around stars from which Jovian planets can form.
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The first small solid grains or flakes formed in our solar system by the process of ____, the addition of material to an object an atom or molecule at a time.
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condensation
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Accretion among the grains in the solar nebula would have been aided by
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static electricity
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The uncompressed density of a planet in our solar system
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is greatest for the planets closest to the sun.
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If a star is found with five planets orbiting it, and a process like that described in the solar nebula theory formed the planets, which of the planets would be expected to have the greatest uncompressed density?
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The one closest to the star.
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The Jovian planets have lower average densities than the terrestrial planets.
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true
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Based on current observations, ____ has a heavy element core, and a very dense, deep atmosphere made mostly of hydrogen.
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Uranus
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A newly formed planet or large asteroid becomes molten due to ______.
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a. the last infalling objects b. decay of radioactive element isotopes c. Both of the above ( Correct )
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Part of the current atmosphere of Earth is believed to be
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composed of gases that were outgassed from the heated rocks sometime after the planet formed.
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The age of the solar system is believed to be approximately 4.6 billions years based on the data from
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a. samples of lunar rocks. b. samples of Earth rocks. c. samples of meteorites. d. all of the above (correct)
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The solar nebula theory is NOT able to explain which of the following observed characteristics of the solar system? (Another theory would be needed.)
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The formation of hydrogen atoms in the solar system from subatomic particles
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The oldest rocks found on Earth are about ____ years old.
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3.9 billion
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51 Pegasi is important because
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it is the first star like our sun that was found to have a planet orbiting it
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The asteroid belt is found between which two planets' orbits?
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Mars and Jupiter
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The most important effect in clearing the solar nebula of gas and dust was
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radiation pressure
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____ are located beyond the asteroid belt (3 AU) from the sun, have extremely large masses and very low densities.
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Jovian planets
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Which one of the following IS NOT a characteristic of terrestrial planets?
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low average density
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Once a terrestrial planet had formed from a large number of planetesimals, heat could have melted it and allowed it to differentiate into metallic core of ____ density and a rocky mantle or crust of ______ density.
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higher; lower
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The present motions of the planets were inherited from the rotation of the solar nebula.
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true
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After the first solid grains formed in our solar system, these particles could then grow by the process of ____, the collision and sticking of one particle with another to continue the formation of planetesimals. Each of these has many atoms or molecules.
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accretion
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Which one of the following IS a characteristic of Jovian planets?
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low average density
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How is radioactive dating used to determine the age of an object?
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Both the amounts of radioactive and decay material are measured. Using these with the radioactive material's half-life, the age can be estimated. (Correct)
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____ pushed gas and dust particles out of the solar nebula by the light from the sun.
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Radiation pressure (Correct)
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If the terrestrial planets were formed by homogeneous accretion, then
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they were initially collections of solid particles which melted then differentiated into a high density iron metal core and low density silicate crust. Correct
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The condensation sequence suggests that ____ should condense as solids closest to the sun.
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metals and metal oxides Correct
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When particles in the solar nebula grew large enough, they stopped growing by accretion and began growing by condensation.
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false
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The iron in our solar system was created from smaller mass atomic nuclei in ______.
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supernovas
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Accretion is
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the adding of material to an object by collection of solid particles
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How is the presence of space debris accounted for by solar system models?
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a and b
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On a photograph of the moon, the moon measures 30 cm in diameter, and a small crater measures 0.2 cm. The moons physical diameter is 1738 km. What is the physical diameter of the small crater?
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about 12 km
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The solar nebula theory is NOT able to explain which of the following observed characteristics of the solar system? (Another theory would be needed.)
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The formation of hydrogen atoms in the solar system from subatomic particles
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The pressure of sunlight was one of the forces that cleared the solar nebula.
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true
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____ are located beyond the asteroid belt (3 AU) from the sun, have extremely large masses and very low densities.
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Jovian planets
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Protoplanets of the Jovian planets could have grown very hot from
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the in-fall of material at high velocity. Correct
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The condensation sequence cannot explain the composition of the terrestrial and Jovian planets.
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false
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Protoplanets
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grew in size by the collision and coalescing of planetesimals.
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The hyrdogen and helium in our solar system were created from subatomic particles about ______ years ago.
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14 billion
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Compared to the terrestrial planets, Jovian planets
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have a much larger diameter.
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____ is a solar system object that enters Earths atmosphere and becomes very hot due to friction between the object and Earths atmosphere. It does not survive to reach the surface.
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meteoroid
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Venus is often called Earths sister planet because it is similar to the Earth in terms of
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a. mass b. size c. density d. all of the above (Correct)
