Chapter 9: Venus

Venus is inside Earth’s orbit.

Why does Venus never stray too far from the Sun in the night sky, and does not set too long before or after the Sun does?

0.7

Venus is ___ AU from the Sun.

47°

Venus is never more than ____ from Sun.

3 hours

Venus is seen at most ______ before sunrise or after sunset - sometimes called the “morning star” or “evening star”.

third

Venus is the _____ brightest object in the night sky.

It’s farthest from the Earth; Superior conjunction.

One might expect Venus to be brightness during the “full” phase, but it is not. Why? What is this point called?

Inferior conjunction

When Venus is closest, it is also not brightest because it is in the “new” phase. What is this point called?

At its greatest elongation (39° or 0.47 AU from the Sun); appears as crescent

At what point in its orbit does Venus appear brightest?

The point in Venus's orbit when it is farthest from Earth, leading to reduced brightness.

What is superior injuction?

The point in Venus's orbit when it is closest to Earth, occurring when it is positioned between Earth and the Sun.

What is inferior injuction?

No moon

Does Venus have a moon?

Similar radius, mass, and density.

In what ways is Venus similar to Earth?

243 Earth days

How long does it take Venus to complete one rotation?

the direction of rotation is opposite that of Earth’s and most other solar system objects.

Venus a retrograde rotation, which means…

below the ecliptic plane

Venus’s north pole lies ________.

177.4º; perpendicular

Venus’s axial tilt is _____, but notice it is about _______ to the ecliptic plane.

117 Earth days (1 solar day on Venus); a little more than a Venus year (225 Earth days)

How long does it take Venus to orbit the Sun?

Due to an impact from a very large body; the impact was sufficient enough to slow its rotation to nearly zero.

Why is Venus rotating so slowly?

We cannot observe Venus’ surface at visible wavelengths due to its thick atmosphere.

Why is it difficult to see Venus’s surface?

730 K

What is the surface temperature of Venus?

Ishtar Terra and Aphrodite Terra

What are the names of the two major elevated plateaus or “continents” on Venus?

No plate tectonics

Does Venus have plate tectonics?

Lakshmi Planum; Maxwell Montes (Venus’s largest mountain)

Ishtar Terra is dominated by the _______, which is surrounded by the ______ range.

Cleopatra

To the right of the Max Montes range is the ______ crater, which was formed from the largest meteor impact.

Mead

What is the largest impact crater on Venus?

Volcanic activity; It’s thick atmosphere acts as a protective blanket and makes it difficult for meteors to pass through. Some are from impacts/ejecta blanket

How are most craters formed on Venus and why?

Form when lava wells up at a “hot spot” in the crust and are built up over time by continued eruptions (examples: Sif Mons and Gula Mons); not connected to plate tectonics.

What is a shield volcano?

Sulfur dioxide fluctuates in Venus’s atmosphere and bursts of radio waves similar to bursts observed from volcanos on Earth.

What evidence do we have to suggest that there is current volcanism on Venus?

No

Have we directly observed volcanoes erupting on Venus?

No regular, steady release of heat from Venus’s interior; after millions of years of the pent up energy is released in wide catastrophic event, causing dramatic changes to the surface.

What is the consequence of Venus not having plate tectonics?

Venus has a higher surface temperature and greater pressure.

How does the temperature and pressure of Venus’s atmosphere compare to Earth’s?

Thick, reflective sulfuric acid; creates a haze, yellow-ish hue.

What is the composition of the clouds on Venus? This causes Venus to be what color?

96.5% carbon dioxide, 3.5% nitrogen. Traces of water vapor, carbon monoxide, sulfur dioxide, and argon.

What is the main constituent of the atmosphere on Venus?

A phenomenon where increased carbon dioxide levels trap heat in the atmosphere, leading to extreme temperature rises and potential catastrophic changes.

What is the runaway greenhouse effect?

The greenhouse gases never left the planet because Venus was hotter. Water did not condense out to form bodies of water and neither did carbon dioxide.

Why does the greenhouse effect occur more intensely on Venus?

Venus’ atmosphere collects greenhouse gases and causes the temperature to increase.

How is the surface of Venus affected by this strong greenhouse effect?

It probably has a solid metal core and liquid outer core, but it rotates too slowly.

What is the likely reason that Venus does not have a magnetic field?

We can’t send seismic equipment because it’s too hot, but we predict it’s similar to Earth’s when it was about 1 billion years old.

Why are we uncertain about Venus’s interior?

Interior has not evolved as much, has not been able to cool enough, its energy is going towards volcanic activity and not enough for tectonics, never has large bodies of water.

Why hasn’t Venus developed plate tectonic activity like Earth has?

Terrestrial

What type of planet is Venus?