Chapter 21: Venus and Mars

subsolar point

The point on a planet that is directly below the Sun.

runaway greenhouse effect

A “vicious cycle” (positive feedback) in which a planet’s greenhouse effect causes enhanced release or retention of greenhouse gases that increases the greenhouse effect, and so on. There is evidence that Venus suffered a runaway greenhouse effect early in its history with the result that its oceans boiled away and were destroyed by solar.

composite volcanoes

A volcano built up of layers of lava flows and ash falls. These are steep sided and typically associated with subduction zones.

shield volcano

Wide, low-profile volcanic cone produced by highly liquid lava.

Outflow channels

Geological feature on Mars that appears to have been caused by sudden flooding.

valley networks

Dry drainage channels resembling streambeds found on Mars.

Noachian period

On Mars, the era that extends from the formation of the crust to the end of heavy cratering and includes the formation of the valley networks.

Hesperian period

On Mars, the geological era from the decline of heavy cratering and lava flows and the melting of subsurface ice to form the outflow channels.

Amazonian period

On Mars, the geological era from about 3 billion years ago to the present marked by low-level cratering, wind erosion, and small amounts of water seeping from subsurface ice.

What is true about the atmosphere and surface of Venus?

Its atmosphere contains carbon dioxide, and its surface is shaped by volcanos

What is the highest volcanic peak in the solar system and where is it located?

The Olympus Mons and is located on Mars