Survey of the universe week 4 quiz

The planet closest to the Sun in the solar system is:

Mercury

In studying the surfaces of solid bodies in the solar system, astronomers have learned that the number of craters (per unit area):

is roughly proportional to the age of the surface we are examining

Today, scientists believe that the main reason the Earth has had periodic ice ages is:

slow changes in the tilt of our planet's axis of rotation

Which of the following is NOT evidence that objects from space collide with the Earth?

the crater at the top of the Mount St. Helens volcano

Which of these did the June 1908 impact event in Siberia and the 2013 event in the Russian city of Chelyabinsk have in common?

they both exploded high in the atmosphere and produced a shock wave that reached the ground

Today, a significant amount of new gas is joining the atmosphere of the Earth from what source:

volcanoes release gas that was trapped within the Earth

What is the most important reason that astronomers have learned more about our planetary system in the last 30-40 years than all of history before then.

we have been able to send spacecraft to gather information about planets and moons up close

Which planet in the solar system has not been examined by spacecraft instruments that have either flown by or orbited them?

you can't fool me, spacecraft have visited all the planets in our solar system

On which of the planets (other than Earth) could a human being step out of a spacecraft and survive without any protective gear (special suit, oxygen tanks, etc)?

you can't fool me; there is no other planet on which we could survive unprotected

During the process of differentiation,

heavier materials sink to the centers of molten planets

Which of the following points about our planet's atmosphere is FALSE?

Its mass is a substantial part of the mass of the Earth.

A planet in our solar system whose composition resembles that of our Sun is:

Jupiter

The most abundant gas in the Earth's atmosphere is

Nitrogen

What relatively recent event shows that impacts continue to happen in our solar system even today?

a comet (which broke into more than 20 pieces) hit the planet Jupiter in 1994

When chemists say that a planet's upper regions are reduced,they mean that these regions

are dominated by the element hydrogen and its compounds

What is one way that astronomers have actually gotten an idea of the age of the surfaces of terrestrial planets other than the Earth?

counting craters

In radioactive dating, the measure scientists use to note how long (on average) a particular radioactive nucleus will take to decay is called its:

half-life

In a bad late-night science fiction film, a villain is using a large collection of rare radioactive atoms as energy for a weapon to threaten the good guys. The atoms have a half-life of 1 hour. The villain has 4 kilograms of the radioactive material now, and he needs a minimum of 1 kg. for his weapon to work. After how much time will the weapon no longer be a threat?

just a little after 2 hrs

The rate at which a collection of the same radioactive atoms will decay depends on:

only on internal processes within the atoms; nothing external matters

Today, the chemistry of the terrestrial planets does not include a lot of free hydrogen. Chemists call the chemistry in places like the Earth:

oxidized

The first trans-Neptunian object astronomers found (in 1930) is called

pluto

All the planets (without exception)

revolve around the Sun in the same direction

Scientists have been concerned about a set of industrial chemicals called CFC's (chlorofluorocarbons) because they:

rise into the atmosphere and destroy ozone

In the four terrestrial planets, the densest, heaviest materials are at the center and not evenly distributed throughout the planet. Scientists interpret this observation to mean that:

the four terrestrial planets must once have been hot enough to be molten (like a liquid)

An increase in the Earth's temperature by several degrees Celsius would result in:

the melting of many glaciers, a rise in sea levels, and more flooding of towns near the coasts of the continents

For scientists, one bar is

the pressure with which 1 square centimeter of the Earth's atmosphere presses down at the surface

In the far future, a visiting tourist from another planetary system asks to see the most massive object in our solar system. Where would you take him/her/it?

the sun