Astronomy HW# 7
A planet in our solar system whose composition resembles that of our Sun is:
Jupiter
Which of the following is NOT a terrestrial planet?
Jupiter
The planet closest to the Sun in the solar system is:
Mercury
Put the following members of our solar system in order of mass, from the most massive to the least massive.
Sun, Jupiter, Earth, Pluto, Asteroid Sydneywolff
Of the following planets, which does NOT have satellites (moons)?
Venus
On which planet (besides the Earth) do we still see a high level of geological activity on the surface today?
Venus
Which of the following places is most likely NOT to be differentiated?
a small asteroid
At the beginning of the solar system's history, a ready supply of proto-planets or mini-planets crashed into the developing planets and each other -- something astronomers call the "era of giant impacts." How long do astronomers estimate this era lasted?
about 100 million years (0.1 billion)
Radioactive dating techniques have revealed that our Earth and Moon are approximately how old?
about 4.5 billion years
The smaller objects in the solar system made of rock and metal (most of which orbit between Jupiter and Mars) are called:
asteroids
The smaller objects in the solar system composed mainly of ices (frozen gases) that usually orbit far from the Sun are called:
comets
What is one way that astronomers have actually gotten an idea of the age of the surfaces of terrestrial planets other than the Earth?
counting craters
One of the best proofs that our theory of how the solar system formed is correct is that astronomers now observe
disks around other stars which show evidence of gaps where planets may be forming
One piece of evidence that can help astronomers sort out how the planets in our solar system formed is
finding circumstellar disks of material around nearby stars
During the process of differentiation,
heavier materials sink toward the centers of planets that are in a liquid or gas state
If you were to take a large sample of the four giant planets, the most common element you would find in them is:
hydrogen
The inner planets are made mostly of rock and metal because:
it was so hot where the inner planets formed that the lighter materials evaporated
In general, the further planets are from the Sun, the cooler they are. What other factor can have a significant influence on a planet's surface temperature?
its atmosphere (whether it has one and how thick it is)
Which of the following ways that jovian (giant) planets differ from the terrestrial planets is NOT CORRECT?
jovians (being larger) rotate significantly more slowly than terrestrials
The material that would eventually make all the major bodies in our solar system first gathered together into smaller pieces which astronomers call:
planetesimals
When the solar system was forming, the building blocks from which the protoplanets gathered together were the:
planetesimals (a few km to tens of km wide)
All the planets (without exception)
revolve around the Sun in the same direction
Astronomers now believe that the differences in composition among the planets reflect what characteristic in the early solar system?
temperature
Which of the following is NOT a characteristic that worlds in our solar system have in common:
that all the planets have solid surfaces on which we can see impact craters
In the four terrestrial planets, the densest, heaviest materials are at the center and not evenly distributed throughout the planet. Scientists interpret this observation to mean that:
the four terrestrial planets must once have been hot enough to be molten (like a liquid)
Which of the following pieces of observational evidence does our modern "solar nebula" theory of the formation of the solar system NOT explain directly?
the plane of the orbit of Pluto
Astronomers call the vast, rotating cloud of vapor and dust from which the solar system formed:
the solar nebula
Our best evidence and theoretical calculations indicate that the solar system began with a giant spinning system of gas and dust that scientists call:
the solar nebula
Which of the following characteristics do all four terrestrial planets have in common?
they all have solid surfaces with signs of geological activity on them
Which of the following is NOT a way that Jovian planets can be distinguished from terrestrial planets?
they have many more craters from collisions that happened early in solar system history
A key difference between the protoplanets that formed in the outer solar system and those that formed in the inner solar system was that
those in the outer solar system were in a place where ice, not just rock, condensed and thus could grow larger
What is the most important reason that astronomers have learned more about our planetary system in the last 30-40 years than all of history before then.
we have been able to send spacecraft to gather information about planets and moons up close
Which planet in the solar system has not been examined by spacecraft instruments that have either flown by or orbited them?
you can't fool me, spacecraft have visited all the planets in our solar system
