Astronomy test 2
Earth's magnetic field is thought to be produced by the...
...the motion of the metallic liquid outer core.
A planet has a density of 6000 kg/m^3. Approximately what fraction of the planet is metal?
0.6
diffuse reflection
light gets scattered in all direction
nuclear fusion
light nuclei join to form a heavier nucleus, releasing energy as they do so
Describe Mars' atmosphere
low escape speed, no magnetic field, very thin atmosphere
Why doesn't Mercury have an atmosphere?
low escape speed, too small to have a strong magnetic field to protect it from the sun's solar winds
Why is a magnetic field helpful in retaining an atmosphere?
magnetic field shields the atmosphere from being blasted away by the solar wind.
Which two factors determine the escape speed from the surface of a planet?
mass and radius
The Galilean moons range in magnitude from 4.6 to 5.6 under the best viewing conditions. Should you be able to see them with the naked eye?
yes
If the volume of an object is doubled, by what factor does its density change?
1/2
If the radius of a planet is tripled, by what factor does its density change?
1/27
If the radius of a planet is doubled, by what factor does its density change?
1/8
What is the speed of sound in water?
1480 m/s
Planet X has a radius 2.6 times that of Earth, and a mass 5 times that of Earth. What is its escape velocity, in km/s?
15.5 km/s
An asteroid has a radius of 1.2×105 m and a mass of 2.7×1019 kg. With what speed would a cannon ball need to be fired so that it could completely escape from the asteroid?
173 m/s
Waves at the beach are separated by 5 m, and it takes about 2 seconds from when one wave passes you until the next arrives. With what speed are the waves moving?
2.5 m/s
If the mass of an object is tripled, by what factor does its density change?
3
The speed of light in a vacuum is...
300,000 km/s
density of rock?
3000 kg/m^3
Mars has a mass of 6.42 x 10^23 kg and a radius of 3.4*10^6m. What is the density of Mars?
3880 kg/m^3
Planet Z has a mass of 6.5×10^24 kg and radius 7.0×10^6 m. What is the density of Planet Z?
4524 kg/m^3
Mars has a mass of 0.11 M Earth and a radius of 0.53 R Earth. What is the escape speed from Mars's surface, in km/s?
5.1 km/s
A planet can retain a gas if the escape speed is at least____times greater than the average speed of the molecules in the gas.
6
What would Mercury's mass have to be in order for it still to have a nitrogen (molecular weight 28) atmosphere?
6.7×10^−2 Earth masses
density of metal?
7900 kg/m^3
What is the primary cause of the aurora (Northern and Southern lights)?
Charged particles interacting with the atmosphere
solar flare
A sudden eruption of intense high-energy radiation from the sun's surface, happens in seconds
How do the wavelengths of infra-red (IR) light compare to the wavelengths of visible light?
IR wavelengths are longer than visible wavelengths.
Earth and Venus likely started with very similar atmospheres. What happened to make them so different?
Carbon dioxide dissolved into Earth's oceans and rocks, thinning out the atmosphere.
What caused the scarps found on Mercury?
Cooling of the planet and shrinking of the crust
What natural phenomenon on Earth provides information on the structure of Earth's core?
Earthquakes
who was the first to see Jupiter's largest moons?
Galileo
big seven moon?
Ganymede, Titan, Callisto, io, Earth's moon, Europa, Triton
what is most widely accepted explanation for the Moon's origins?
Giant Impact theory: Moon was formed when a giant object (Mars size!) collided with the young Earth
Prominences
Huge reddish loops of gas, lasts for weeks, low energy
The main constituent of Jupiter's atmosphere is
Hydrogen
What is the current leading theory for the Moon's formation?
Impact of a large object with the early Earth, followed by coalescence and capture of the resulting fragments
Which of the following is true regarding the speed of light?
It is constant for all electromagnetic waves traveling in a vacuum.
On which planet can you find The Great Red Spot?
Jupiter
The low densities of the Jovian planets tell us they are mostly composed of what materials?
Light gases
You see a blue house. Which of the following statements is correct?
Only blue light is reflected from the house; all other light is absorbed.
What are the requirements for a planet to have a magnetic field?
Rapid rotation and an electrically conducting core.
Titan
Saturn's largest moon
What best describes the Earth's inner core?
Solid metal
A planet has a density of 3200 kg/m^3. Based on this information alone, which of the following statements is true?
The planet is mostly rocky, containing very little metal.
In terms of size and mass, which planet is most similar to Earth?
Venus
absorption lines
Visible lines on an observed color spectrum that reveal the chemical composition of the light source
What are Saturn's rings made of? Why are they disappearing?
Water ice with traces of another material, they are raining away
A planet has an escape speed of 15,000 m/s. The average speed of a molecule of oxygen on this planet is 900 m/s. Is this planet able to retain oxygen in its atmosphere, or does the oxygen escape into space?
Yes, it can retain oxygen because the escape speed is greater than 6 times the average speed of an oxygen molecule.
nuclear fission
a heavy nucleus splits into two (usually) lighter nuclei and releasing a lot of energy.
Essentially, the Great Red Spot is
a large cyclonic storm (hurricane).
coronal mass ejection
a large explosion of matter and energy from the Sun, happens in a few hours
What is thought to lie at the center of Jupiter?
a massive core of rocky materials with some iron mixed in
wave period
a measurement of the amount of time needed for a wave to repeat itself at some point in space.
Uranus axial tilt
almost horizontal
Mercury's axis is...
almost vertical, causing extreme heat and cold
light is...
an electromagnetic wave
Like Olympus Mons, volcanoes on Venus...
are shield volcanoes
Ganymede
largest moon in the solar system, surface contains lots of water ice, thought to have a subsurface ocean
differential rotation
because the gas giants are not solid, the planet can rotate at different speeds at different latitudes
Callisto
composed of ice rock mixture
specular reflection
light beams reflect at the same angle as they arrive. This is how mirrors reflect light.
Alternating zones of rising and sinking gas in Jupiter's atmosphere...
create light and dark bands.
Ganymede has an internal structure while Callisto does not. Astronomers say that Ganymede is...
differentiated
blackbody radiation
emission of light from hot objects, they do not reflect light only absorb
The number of waves that pass a point each second measures...
frequency
A wave's velocity is the product of the...
frequency times the wavelength of the wave.
Europa
geologically active, surface of water ice, thought to have a liquid ocean beneath it's surface
atmospheres are likely when a planet...
has a high escape speed and a magnetic field
Venus rotates...
in the opposite direction from the Earth but very slowly.
We have one cubic meter each of rocks, iron, and water. Rank them from heaviest to lightest.
iron, rock, water
If a wave's frequency doubles and its speed stays constant, its wavelength....
is halved
Based solely on Mercury's density, we can infer that...
it must contain a relatively high metal content.
Table 9.1 gives the average density of the Sun as 1410 kg/m^3. Is this more similar to the density of the terrestrial or Jovian planets?
jovian
The reason the jovian planets lost very little of their original atmosphere is due to their...
large mass
Waves at the beach are separated by 5 m, and it takes about 2 seconds from when one wave passes you until the next arrives. What information has been given in this problem?
period and wavelength
Earth's rotates in the___________direction while Venus rotates in the_________direction.
prograde, retrograde
What is the order of the EM spectrum?
radio, infrared, visible light, ultraviolet, x-ray, gamma ray
range of wavelengths from visible light?
red (700) to blue (400)
Why does Earth have an atmosphere?
strong enough gravity to hold on to heavy gas molecules and protective magnetic field to shield from the solar wind
What did radar astronomers find in the polar regions of Mercury?
temperatures cold enough to allow thin sheets of water ice
Roche Limit
the distance a moon can be from a planet before shattering from tidal forces
Mercury's surface most resembles which of these?
the lunar far side
Amplitude
the maximum height or depth of the wave above or below the undisturbed state.
escape speed
the speed needed for a projectile to completely escape the gravitational pull of an object
Luminosity
the total amount of energy radiated by an object every second
Photosphere
the visible surface of the sun
Jupiter and the other jovian planets are noticeably oblate because...
they are fluid bodies that are spinning rapidly
What is the most likely heat source for keeping Europa's water liquid?
tidal forces from Jupiter
rank the planets from hottest to coldest daytime temperatures.
venus, Mercury, Earth, Mars
io
very few craters, most geologically active object in the solar system, many volcanoes
why do moons have craters?
when they have an old surface and lots of geological activity