Week 8

How does the Sun influence the tides that we experience on Earth?

The Sun also raises tides on Earth, but its effect is smaller than that of the Moon.

Which of the following would NOT be one of the problems faced by an unprotected Earthling stranded on Mars? (Unprotected meaning no space suit.)

The extreme (high) heat at most latitudes

Which group contains only features that can be seen on the surface of Mars today?

craters, canyons, polar caps, volcanoes

How do most astronomers today believe the Moon formed?

A Mars-sized object struck the young Earth, and the ejected debris formed the Moon.

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.

What gas makes up most of the atmosphere of Mars?

Carbon Dioxide

What is the dominant gas in Venus's atmosphere?

Carbon dioxide

Why is Venus's surface hotter than Mercury's?

Carbon dioxide in Venus's atmosphere traps heat radiating from its surface, thereby making it warmer.

In its overall composition, the Moon roughly resembles

Earth's crust and mantle.

What theory of Mercury's origin can best explain the fact that its core is made of such dense materials?

Giant impacts in its early history may have torn away much of its original crust and mantle.

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).

What is odd about Mercury's motions?

It spins three times for every two orbits around the Sun.

Which of the following is a way that the planet Mercury is similar to the Moon?

Its surface is heavily cratered.

Mars appears to have long branching channels that have the appearance of being formed by a flowing liquid. Yet we know that water cannot stay liquid in the very thin atmosphere. How can we explain the channels?

Mars had a thicker atmosphere long ago when the channels formed.

Mercury's average density is about 1.5 times larger than the Moon's even though the two bodies have similar radii. What does this suggest about Mercury's composition?

Mercury's interior is much richer in iron than the Moon's.

How were the maria formed?

Molten rock from the Moon's interior flooded the huge basins after large impacts.

Which of the following statements about our Moon is FALSE?

On Earth, we can see all its sides in the course of a month as it goes around us.

Venus is completely covered by a thick layer of clouds all the time. What wavelength of electromagnetic radiation can be used to study the surface from orbit?

Radio waves (like radar)

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.

Which of the following is NOT a way that Venus resembles the Earth?

The thickness and pressure of its atmosphere

Mars rovers (such as Opportunity and Curiosity) have identified evidence that their landing sites were once under water. Which of the following is among the kinds of evidence they have identified?

They found rock formations that show the area was under water and minerals that only form in water.

A crucial difference that helps explain why Venus is so hot and the Earth isn't is that

on Venus, there was eventually no ocean to remove carbon dioxide from the atmosphere.

Venus is unusual because of its retrograde rotation. This means that Venus

rotates on its axis in the opposite direction compared to most other planets in the Solar System.

The Moon

rotates on its axis with the same period as its revolution around Earth.

The lunar highlands have more craters than the maria because

the maria are much younger than the highlands.