Astronomy Ch. 9 – Venus

Venus is brightest as seen from Earth:

36 days before or after inferior conjunction, appearing as a large crescent.

At closest approach Venus is about how far from Earth?

0.3 AU

Venus’ full phase occurs when Venus is at:

superior conjunction.

In the time between two closest approaches to Earth, Venus rotates almost exactly five times relative to the sun. The consequence of this is that:

Venus always presents the same face to Earth at inferior conjunction.

Venus orbits the Sun in 225 days. How long does it take to rotate on its axis?

243 days, even though the Earth’s tidal pull is not involved

Why is it reasonable to conclude that the internal structure and evolution of Venus are basically Earthlike?

They have similar masses and sizes.

Venus’ rotation:

takes longer than its orbit around the Sun.

Through radar observations it was found that Venus’

rotation on its axis is retrograde.

Why does Venus appear so bright to the eye?

As seen from Earth, the disk of Venus can appear larger than any other planet’s. The planet’s cloud-cover is highly reflective, reflecting 60% of the sun’s light. Venus is closer to the Sun, so gets more intense sunlight. It gets closer to us than any other planet does. All of the above are correct.

Earth and Venus are often called sister planets; in which ways are they most alike?

size, density, and surface gravity

What resonance exists between Venus’ rotational period and its synodic period?

5:1, with the Earth always closest to the same side of Venus when they pass

Because of its slow rotation period, Venus:

presents the same side to Earth at each closest approach.

The synodic period of Venus is about how many Earth years?

about 3.5 years

Venus is only a little bit (5%) smaller than Earth, and its density is only slightly less than Earth’s. Therefore, its mass is:

just a little bit less than Earth’s.

The surface of Venus can be observed with:

radar observations from Arecibo.

The synodic period of Venus is the time it takes for:

Venus to complete a full cycle of phases.

Our most detailed maps of Venus come from:

the Magellan spaceprobe.

Our best data about the surface topography of Venus has come from:

Magellan radar data and radar observations of the planet from Earth.

The orbiter that gave us the most detailed maps of Venus to date was:

Magellan.

Which of the following characterizes a shield volcano?

It sits above a hot spot in the planet’s mantle.

Which statement is true of Venus’ surface?

There are two continent sized uplands.

Compared to Earth, Venus has:

a far greater percentage of its surface in low-level ocean basins.

A surprise from the Pioneer Venus photos was that:

the clouds rotate around the planet in only four days, very unlike the slow surface rotation.

Venus has a feature named Aphrodite Terra. What is this feature?

a continental-sized plateau

Maxwell Mons on Venus is a huge:

shield volcano.

What percentage of the surface of Venus could be characterized as continental-sized highlands?

less than 10%

Various observations suggest there may be recent or even continuing volcanic activity on Venus. Which of the following has NOT been observed?

spacecraft detection over a period of days of flowing lava on Venus

What is thought to have caused the craters on Venus?

Most are volcanic in origin; some are due to meteoritic impacts.

Magellan did not find which of these on Venus?

actual volcanic eruptions in progress

The largest volcanic structures on Venus are called:

coronae.

The only spacecraft to successfully land on Venus were:

Russian Veneras.

Why will it be hard to determine the nature of Venus’ interior?

No seismograph can last long enough at Venus’ temperatures to pick up quakes.

The highest peak on Venus is called:

Maxwell.

The rilles found in Ovda Regio are evidence of:

lava flows.

A characteristic of shield volcanoes is the formation of a crater at the summit which occurs when:

the lava withdraws and the surface collapses.

The relatively small number of impact craters and the near absence of small craters on the surface of Venus is thought to be a result of:

the soft and resilient nature of the Venusian surface.

Volcanic activity on Venus is thought to be:

less frequent, but more violent than volcanic activity on Earth.

The main problem spacecraft have encountered in landing on Venus is:

the extremely high temperatures.

The atmospheric pressure on Venus:

is much higher than on Earth.

What is the result of the Greenhouse effect on the surface environment of Venus?

It has raised the surface temperature by hundreds of degrees Celsius

What is the main constituent of the atmosphere of Venus?

carbon dioxide

Because the atmosphere of Venus is so dense,

clouds cannot form.

The fact that Venus’ atmosphere contains carbon dioxide was discovered:

in early spectroscopic studies.

The reason that the atmosphere of Venus is over 95% carbon dioxide is thought to be because:

Venus was much hotter than Earth when its atmosphere formed.

What is the composition of the clouds of Venus?

sulfur and sulfuric acid droplets

If Venus once had an ocean, where did it go?

The water broke into hydrogen, which escaped to space, and oxygen, which became trapped in the planet’s surface rocks.

Comparing the clouds of Earth and Venus, we find that:

ours lie in the troposphere, within 10 kilometer of our surface, but Venus has a higher troposphere, with its clouds about 40 kilometers high.

The absence of a magnetic field on Venus probably stems from its:

slow rotation.

Which of the following contributes to Venus being so hot?

Its atmosphere is made chiefly of carbon dioxide. It is closer than Earth to the Sun. It has very little axial tilt so the equator is always directly exposed to the Sun. Its atmosphere is much denser than the Earth’s. All of the above are factors.

Venus’ lack of magnetic field means that:

Venus’ upper atmosphere is permanently ionized.

(SA) Describe how conditions on Venus have produced a runaway Greenhouse Effect.

Because of Venus’ proximity to the Sun, carbon dioxide never got absorbed by surface rocks due to higher temperature. Carbon dioxide is a greenhouse gas and traps heat, so this led to still higher temperature, leading to even more carbon dioxide released from rocks in a vicious cycle. The result is a surface temperature of 730 K.