Astronomy Ch. 1-3

Suppose that instead of being inclined to Earth's orbit around the Sun, the Moon's orbit was in the same plane as Earth's orbit around the Sun. In this hypothetical situation, approximately how many solar eclipses would occur each year?

12

In reality, the Moon's orbit about Earth is tilted (by about 5°) with respect to Earth's orbit about the Sun. As a result, the actual number of solar eclipses that occur each year is approximately _____

2

What is not true about a scientific theory?

A theory is essentially an educated guess.

Although the Causes of Lunar Phases video is very useful for learning about phases of the Moon, it is inaccurate in some ways. Which of the following correctly identify inaccuracies with this video?

Earth is too big compared to the Moon's orbit. The Moon is too big compared to its orbit. The Moon is too big compared to Earth. The astronaut is too big compared to the Moon.

An astronomical unit is:

Earth's average distance from the Sun

Kepler's third law states that a planet's orbital period, p, is related to its average (semimajor axis) orbital distance, a, according to the mathematical relationship p^2=a^3. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's third law?

Inner planets orbit the Sun at higher speed than outer planets. Venus orbits the Sun faster than Earth orbits the Sun.

Sun Centered Model

Mercury goes through a full cycle of phases positions of nearby stars shift slightly back and forth each year

Kepler's second law states that as a planet orbits the Sun, it sweeps out equal areas in equal times. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's second law?

Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.

In winter, Earth's axis points toward the star Polaris. In spring, the axis points toward __________

Polaris.

What is not true about scientific progress?

Science advances only through the scientific method.

Kepler's first law states that the orbit of each planet is an ellipse with the Sun at one focus. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's first law?

The Sun is located slightly off-center from the middle of each planet's orbit. Earth is slightly closer to the Sun on one side of its orbit than on the other side

As you play the Moon Orbit video, notice how the arrows representing the Sun's rays are at first spread apart but become parallel as the video zooms in on the Moon's orbit. Why do the Sun's rays become parallel at the end of the video?

The Sun is so far away compared to the size of the Moon's orbit that all the rays reaching the orbit come from essentially the same direction.

When we say the universe is expanding, we mean that:

The average distance between galaxies is growing with time.

Beijing and Philadelphia have about the same latitude but different longitudes. What can be said about the tonight's night sky in these two places?

The sky will look about the same.

What is the cause of the seasons?

The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year.

What best describes how variation in the Earth-Sun distance affects the seasons?

The variation in Earth-Sun distance over the course of each year has virtually no effect on the seasons.

As the Moon orbits, notice how the astronaut's head always points toward Earth. What do we see from Earth that occurs for the same reason? (Be sure you are viewing the first portion of the video, with the rotating Moon, not the hypothetical, non-rotating view, shown afterward.)

We always see the same face of the Moon.

Why is it generally hotter in summer than in winter?

We have more hours of daylight in summer. The Sun is higher in the sky in summer.

Earth Centered Model

a planet beyond Saturn rises in west, sets in east

To understand phases of the Moon, you must imagine the view from Earth looking out to the Moon as it orbits. At what position(s) in its orbit would we see all of the Moon's daylight side and none of its night side?

at the point on the far left

At what position(s) in the Moon's orbit would we see exactly half of the Moon's daylight face and exactly half of its night face?

at the two points at the top and bottom

Notice that Earth's daylight side (white) is on the right in this view, and its night side (gray) is on the left. Where along its orbit would the Moon also have its daylight side on the right and its night side on the left?

everywhere along its orbit

When Einstein's theory of gravity (general relativity) gained acceptance, it demonstrated that Newton's theory had been _____________

incomplete.

We never see a crescent Jupiter from Earth because Jupiter __________.

is farther than Earth from the Sun

If we wanted to show the Moon's orbit on the scale of this starting frame, we would need to draw a circle that __________.

is smaller than one of the green dashes that show Earth's orbit

What conditions must exist for a lunar eclipse to occur?

it must be full moon; the Moon must be passing through Earth's orbital plane

Galileo's contribution to astronomy included:

making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.

Both Sun and Earth Centered Models

stars circle daily around north or south celestial pole Moon rises in east, sets in west a distant galaxy rises in east, sets in west each day

What conditions must exist for a solar eclipse to occur?

the Moon must be passing through Earth's orbital plane; it must be new moon

The total number of stars in the observable universe is roughly equivalent to:

the number of grains of sand on all the beaches on Earth.

Consider the hypothetical observation "a planet beyond Saturn rises in west, sets in east." This observation is not consistent with a Sun-centered model, because in this model __________.

the rise and set of all objects depends only on Earth's rotation

our cosmic address listed in order from largest to smallest

the universe, the local supercluster, the local group, the Milky Way Galaxy, our solar system, Earth

Neither a Sun nor Earth Centered Model

we sometimes see a crescent Jupiter

The star Betelgeuse is about 600 light-years away. If it explodes tonight,

we won't know about it until about 600 years from now.