Deck 4: Space and Time

Question 1

Describe the nebular hypothesis, from gravitational collapse to differentiation. Describe how the solar system eventually ended up with two categories of planets: Terrestrial and Jovian.

Answer 1

The nebular hypothesis is a widely accepted theory for the formation of the solar system. It suggests that the solar system formed from the gravitational collapse of a giant molecular cloud, or nebula.

The process began with the gravitational collapse of a cloud of gas and dust, which caused the material to start spinning and flattening into a rotating disk. As the disk continued to collapse under its own gravity, the central region became denser and hotter, eventually leading to the formation of the Sun.

Meanwhile, in the outer regions of the disk, small particles collided and stuck together, forming planetesimals. These planetesimals continued to grow through collisions and accretion, eventually forming protoplanets.

As the protoplanets continued to grow, the inner regions of the solar system became too hot for volatile materials such as water and gases to condense, leading to the formation of the terrestrial planets (Mercury, Venus, Earth, and Mars) which are small, rocky, and close to the Sun.

In the outer regions of the solar system, where it was cooler, volatile materials were able to condense, leading to the formation of the Jovian planets (Jupiter, Saturn, Uranus, and Neptune) which are large, gaseous, and farther from the Sun.

This differentiation in the composition and size of the planets is a result of the temperature gradient within the protoplanetary disk, with the terrestrial planets forming closer to the Sun and the Jovian planets forming farther away. This process led to the formation of the two categories of planets within the solar system.

Question 2

Use the H-R diagram to describe the evolutionary fate of our Sun. Presently, the Sun is located on the Main Sequence. What will be the fate of our Sun in about 5 billion years? From now until then, what will be the evolutionary journal for the Sun?

Answer 2

The Hertzsprung-Russell (H-R) diagram is a graph that shows the relationship between the luminosity and temperature of stars. On the H-R diagram, the Sun is currently located on the Main Sequence, which is the band where most stars, including our Sun, spend the majority of their lives.

In about 5 billion years, the Sun will exhaust its hydrogen fuel in its core and will start to undergo significant changes. As a result, it will leave the Main Sequence and begin to evolve into a Red Giant. During this phase, the Sun will expand to many times its current size and become much more luminous. This expansion will likely cause it to engulf Mercury and Venus, and possibly even Earth, as it becomes a Red Giant.

After the Red Giant phase, the Sun will shed its outer layers, forming a planetary nebula, and leave behind a small, hot core known as a white dwarf. This white dwarf will slowly cool over billions of years, eventually becoming a cold, dark remnant of our once vibrant Sun.

So, the evolutionary journey for the Sun from now until its eventual fate as a white dwarf will involve leaving the Main Sequence, becoming a Red Giant, shedding its outer layers to form a planetary nebula, and finally ending its life as a white dwarf.

Question 3

As the Earth revolves around the Sun, the seasons on Earth are caused by the __________ of the Earth relative to the plane of the ecliptic.

Answer 3

tilt

Question 4

Nuclear fusion occurs in the __________ of the Sun.

Question 5

Mercury, Venus, Earth, and Mars are called the __________ planets.

Question 6

__________ are subplanetary objects orbiting the Sun.

Question 7

The atmospheres of the Jovian planets are composed mainly of __________ and helium.

Question 8

The length of a stars life is primarily determined by its __________ .

Question 9

Our solar system formed from a large cloud of gas and dust called a __________.

Question 10

The __________ provides a "guesstimate" to the number of civilizations in our galaxy.

Question 11

With only a few exceptions, __________ is the source of energy that sustains life on Earth.

Question 12

There are __________ planets in the solar system.

Question 13

In the model of the solar system, the Earth and the other planets revolve around the Sun.

Question 14

Earth's Moon is approximately _________ the size of Earth.

Question 15

Surrounding the solar system in a spherical mass is the Oort Cloud. The Oort Cloud contains long-period __________ that orbit around the Sun.

Question 16

The __________ can be used to describe the history of a star.

Question 17

A small-mass star will leave a __________ life than a large-mass star.

Question 18

The age of the Sun is about __________ billion years old.

Question 19

__________ has been used to determine the age of Earth and other objects in the solar system.

Question 20

For the principle of __________ , the present is the key to the past.

Question 21

The Sun is the center of our solar system.

Question 22

Earth is one of many planets in the solar system that has liquid surface water.

Question 23

We experience seasons due to the extreme changes of Earth's orbit around the Sun.

Question 24

The innermost planets in the solar system (Mercury, Venus, Earth, and Mars) are large and gaseous.

Question 25

The outermost planets in the solar system (Jupiter, Saturn, Uranus, and Neptune) are small, dense, and rocky.

Question 26

Venus, unlike Earth, Mercury, and Mars rotates in a retrograde motion.

Question 27

The nebular hypothesis proposes that the solar system formed from a huge, swirling cloud of cosmic gas and dust.

Question 28

The planets formed when bits of solid matter from the solar nebula were drawn together by gravitational attraction and accretion.

Question 29

The main factors that influenced the evolution of the terrestrial planets shortly after their formation were impact cratering, volcanism, proximity to the Sun, and absence or presence of a biosphere.

Question 30

All of the terrestrial planets lost their primary atmospheres, but Earth, Mars, and Venus evolved and retained secondary atmospheres.

Question 31

Jupiter and Saturn are so massive that their atmospheric gases never escaped; their atmospheres still maintain compositions very similar to the solar nebula from which they were formed.

Question 32

Earth's Moon is a result of a comet captured within Earth's gravitational field.

Question 33

Stellar classes are based on luminosity and density.

Question 34

Ninety percent of the stars in our galaxy have characteristics similar to those of our Sun.

Question 35

The age of the solar system is about 4.6 million years old.

Question 36

Numerical age is the actual time when a specific event happened.

Question 37

The rate of decay of radioactive materials is affected by geologic processes.

Question 38

The principle of uniformitarianism states that the landscape of the Earth formed via a series of sudden and catastrophic events in Earth's early history.

Question 39

The region of the H-R diagram occupied by most stars is the

A) Giants region.
B) White Dwarf region.
C) Supergiants region.
D) Main Sequence region.

Question 40

A star directly above the Sun on the H-R diagram would generally be __________ than the Sun.

A) Smaller.
B) Larger.
C) A different color.

Question 41

Because of Earth's relatively small mass, our planet's atmosphere is composed

A) Of a large amount of carbon dioxide.
B) Of the same percentages of gases that exist throughout the solar system.
C) Of very little hydrogen and helium.
D) Of gases similar to those of the Jovian planets.

Question 42

The atmospheres of the Jovian planets are made of primarily

A) Oxygen and nitrogen.
B) Methane and ammonia.
C) Liquid metallic hydrogen.
D) Hydrogen and helium.

Question 43

If the Earth had a 90 degree tilt rather than a 23.5 degree tilt, how many seasons would there be?

A) One (little to no seasonal variation).
B) Three (Winter, Spring, Summer).
C) Two (Winter, Summer).
D) Four (Winter, Spring, Summer, Fall).

Question 44

The model in which the Sun is at the center of the solar system is called the

A) Heliocentric model.
B) Geocentric model.
C) Galilean model.
D) Newtonian model.

Question 45

The Sun converts mass into energy by

A) Nuclear fission.
B) Nuclear fusion.
C) Fossil fuel burning.
D) All of the above.

Question 46

The Sun is massive enough to keep burning on the Main Sequence for another

A) 5 billion years.
B) 10 billion years.
C) 15 billion years.
D) 20 billion years.

Question 47

The planets orbit the Sun on or close to

A) The equatorial plane.
B) The galactic plane.
C) The plane of the ecliptic.

Question 48

A carbonaceous chondrite is a type of

A) Asteroid.
B) Comet.
C) Meteorite.
D) Lunar rock.

Question 49

Where is the asteroid belt located?

A) Between the orbits of Mars and Jupiter.
B) Between the orbits of Saturn and Uranus.
C) Between the orbits of Earth and Venus.
D) Outside of the solar system, in the Oort Cloud.

Question 50

As the Sun continues to age, the chemical composition of its core will change. Over time, it will contain a lower percentage of and a greater percentage of .

A) Carbon, lead.
B) Helium, hydrogen.
C) Oxygen, nitrogen.
D) Hydrogen, helium.

Question 51

According to the nebular hypothesis

A) Planets can rotate in any direction around the Sun.
B) Planets should rotate in the same direction as they revolve around the Sun.
C) Planets should rotate one way and revolve the other way.
D) The hypothesis does not indicate direction of rotation or revolution.

Question 52

Most of the exoplanets discovered thus far are

A) Parts of planetary systems very similar to ours.
B) Small planets, most likely resembling Earth.
C) Giant planets, most likely resembling Jupiter.
D) Parts of planetary systems quite different than ours.

Question 53

Life on Earth was able to develop primarily due to

A) Its distance from the Sun.
B) Its size.
C) A combination of its size and its distance from the Sun.
D) The chemical composition of its rocks.

Question 54

Differentiation is a process by which

A) The Earth's surface separated into continents and oceans.
B) Denser materials sink and less dense materials rise to the surface.
C) Less dense materials sink and denser materials rise to the surface.
D) None of the above.

Question 55

The most widely accepted theory for the formation of the Moon is the

A) Giant impact model, in which material was ripped from the Earth after an impact with a Mars size object.
B) Fission model, in which the Moon was spun off of a rapidly rotating Earth.
C) Co-formation model, in which the Moon formed from a rotating disk of gas and dust around the Earth.
D) Capture model, in which the Moon formed in another part of the solar system and was captured by Earth's gravitational field.

Question 56

What is the order of planets, from closest to the Sun to furthest from the Sun?

A) Mercury, Venus, Earth, Mars, Saturn, Jupiter, Uranus, Neptune.
B) Mercury, Earth, Venus, Mars, Jupiter, Saturn, Uranus, Neptune.
C) Mercury, Mars, Earth, Venus, Saturn, Jupiter, Uranus, Neptune.
D) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Question 57

How far away is the Earth from the Sun?

A) 1 Astronomical Unit.
B) 2 Astronomical Units.
C) 3 Astronomical Units.
D) 4 Astronomical Units.

Question 58

Radiometric dating is possible if a rock contains a measureable amount of

A) Parent isotopes.
B) Parent and daughter isotopes.
C) Daughter isotopes.
D) Parent or daughter isotopes.

Question 59

Which of the following moons has an atmosphere?

A) Triton.
B) Ganymede.
C) Callisto.
D) Titan.

Question 60

Our solar system is part of the Milky Way Galaxy. About how many galaxies do astronomers believe exist?

A) 50 billion.
B) 100 billion.
C) 200 billion.
D) 150 billion.

Question 61

What supports and sustains almost all life on Earth?

A) Carbon dioxide.
B) Radioactive decay from the Earth's core.
C) Sunlight.
D) Gravitational forces.

Question 62

The solar system is comprised of eight planets. All of the planets (other than Mercury and Venus) have one or more moons. How many moons have been observed?

A) 8 known moons.
B) 200 known moons.
C) 10 known moons.
D) 170 known moons.

Question 63

What is the Kuiper Belt?

A) A vast repository for asteroids.
B) A vast repository for comets.
C) A vast repository for meteors.
D) The location of Pluto's obit.

Question 64

Icy comets that were originally orbiting in the inner part of the solar system could have met which of several fates?

A) Collision with a planet or planetesimal.
B) The loss of their icy constituents due to volatization.
C) Being swept to the outer part of the solar system by a strong solar wind.
D) All of the above.

Question 65

What is believed to be the reason for Earth's tilt relative to the plane of the ecliptic?

A) The gravitational pull of Mars.
B) The gravitational pull of the Sun.
C) The gravitational pull of Venus.
D) The collision with the Mars sized object called Theia about 4.5 billion years ago (which led to the formation of the Moon).

Question 66

If Pluto is not a planet (but rather a dwarf planet), then where do astronomers believe its point of origin?

A) A comet from the Kuiper Belt.
B) A comet from the Oort Cloud.
C) An asteroid from the Asteroid Belt.
D) A moon from Neptune.

Question 67

Which is the largest planet in the solar system?

A) Uranus.
B) Saturn.
C) Jupiter.
D) Neptune.

Question 68

Which is the smallest planet in the solar system?

A) Earth.
B) Mars.
C) Venus.
D) Mercury.

Question 69

The Great Red Spot is a hurricane-like storm (twice the size of Earth) that has existed on the surface of Jupiter for over 300 years. How is it possible for this storm to have lasted so long?

A) Jupiter's thick and turbulent atmosphere keeps the storm active.
B) Jupiter is all land mass and can support the existence of a hurricane.
C) Jupiter has large oceans that support the creation and existence of hurricanes.
D) Jupiter has patches of hot and cold plumes allowing the hurricane to last a long time.

Question 70

If the ages of the Earth and the Moon are nearly identical, as believed, why are most rocks found on the Moon so much older than rocks found on Earth?

A) The Moon is older.
B) Age dating techniques are just too inaccurate to really know.
C) Unlike the Earth, the Moon has no atmosphere to weather rocks or plate tectonic activity to destroy rocks.
D) None of these.