Chp 10 HW

Mars appears to have long branching channels that have the appearance of being formed by a flowing liquid. Yet we know that liquids would not stay liquid in the very thin atmosphere we have on the Martian surface? So how can we explain the channels?

Mars had a thicker atmosphere long ago when the channels formed

The largest volcano on Mars is called:

Olympus Mons (Mt. Olympus)

The observation that began the 19th and early 20th century fascination with Mars as a place for life was:

Schiaparelli's seeing what seemed to him to be long straight features on the red planet

Why does Mars have an overall reddish color when we see its surface from afar?

The material of Mars' surface contains a lot of iron oxide, the same chemistry that makes rusting metals look reddish

Astronomers estimate that the plains of Venus are only about 500 to 600 million years old. How do they estimate dates like this?

by counting the craters visible on the surface and comparing crater counts to other worlds

Astronomers believe that Mars formed with a much thicker atmosphere than it has today. Where did this atmosphere go?

it escaped into space (and some later froze out as Mars got cold)

The canals that late 19th and early 20th observers thought they saw on Mars turned out to be:

optical illusions

Which of the following is evidence for volcanic activity on Venus?

the discovery of thousands of small volcanic cones of the surface of Venus, the fact that the lava plains are only 500 million or so years old, the existence of large volcanic mountains such as Sif Mons, the pancake domes of Venus

The process by which Venus became so much hotter than the Earth is called:

the runaway greenhouse effect

Which of the following is NOT one of the key reasons that so many spacecraft from Earth have visited Venus and Mars?

their atmospheres are very similar to the Earth in terms of their chemical make-up