PSU Astro 7N Exam 1

What two properties of a planet affect the gravity we feel on its surface?

Mass and radius

Two planets have the same radius. If Planet A is 5 times more mass than Planet B, how does gravity differ on the surfaces of the two planets?

Gravity is 5 times stronger on planet A

Say that there were a planet X in our Solar System with a mass 1/4 the mass of Earth and a radius 1/2 the radius of Earth. How will the gravity on its surface compare to the surface gravity of Earth?

Surface gravity on planet X is the same as on earth

A planet in a nearly circular orbit with its rotation axis tilted by 5 degrees relative to its orbital plane around its star would ...

Have seasons that are not very different from each other as compared to Earth

The rotation axis of the Earth is ...

Tilted at about 23 degrees relative to the axis of the Earth's orbit around the Sun

In the diagram above, what season and planet is being represented by the red X on the planet on the left in orbit around the Sun?

When is the waning gibbous moon highest in the sky?

About 3 am

What phase is the Moon in, when observed by the person standing on the Earth in the diagram above?

New

At what time will the Moon set on the day of a Solar eclipse?

Sunset

Stars that are in the same constellation ...

are likely to be at very different distances from us.

The "North Star" is a star in the constellation of Ursa Minor, which lies just above the North pole of Earth. Which of the following is true?

Ursa Minor is a Zodiac constellation in the summer but not in the winter

A particular Zodiac constellation is high in the sky at midnight in April. Where will it be in October?

Near the Sun in the daytime sky

What do you expect the spectrum of an object that is 1,000,000 Kelvin to be like?

It should peak at X-ray wavelengths

As compared to a cool star, a hotter star emits ...

Shorter wavelength, higher frequency, bluer color

Radio waves can travel large distances without interference because ...

They have longer wavelengths than visible light

Compared to ultraviolet radiation, X-rays have a wavelength that is ...

Shorter

Star A is 4000 K, and Star B is 8000 K. Which of the following is true?

The color of Star A is redder than Star B

In the diagram above, what is happening in the box in the center?

A star is a hot, dense gas surrounded by a cooler, low density atmosphere. What type of spectrum will a star create?

Absorption Spectrum

What makes a transition from a lower energy state to a higher energy state when a photon is absorbed into an atom?

Electron

An emission line is produced when:

An electron passes from a higher to a lower energy level

Bright lines in an emission spectrum represent:

particular energies of light that are emitted from a distant object

The faintness of an object that a telescope can observe is mostly determined by the ...

Diameter of the opening of a telescope

In what ways does a 5 meter telescope outperform a 1 meter telescope?I

its images are 25 times brighter than a 1 meter

A mountain top is a good location for optical telescopes because the site ...

Is above much of the atmosphere

Which statement about the rotation of the Inner planets is true?

Venus rotates in the opposite direction from the three other inner planets

Which of the following is TRUE?

Mercury rotates exactly one and a half times for every one revolution around the Sun.

Why do the orbits of the planets all lie in nearly the same plane?

The early solar nebula flattened into a disk.

Of these choices, which planet has the most moons?

Saturn has more than Earth, Mercury, Mars, and Venus

Venus is visible to us ...

only near sunrise or sunset

A planet is in orbit around the Sun. The semimajor axis of the orbit is 5 Astronomical Units (AU). Use P^2 = a^3 to calculate the period of the orbit, in years.

11.2 years

In the above diagram, how should the parameters of the white curve be changed in order that it matches the observed distance versus time graph of Callisto?

increase P and shift the curve

How do most craters on moons form?

impact of asteroids

Which planet has a temperature of 800 degrees Fahrenheit on the side facing the Sun and -290 degrees Fahrenheit on the side opposite the Sun?

Mercury

How many Earth years does it take Uranus to orbit the Sun?

84

Meteors are ...

asteroids or comet debris that passes into Earth's atmosphere and burns up

Which feature of Neptune is most responsible for its blue color?

methane in its atmosphere

Which of the following statements is TRUE?

The planet Saturn has more than 30 moons.

The surface of Venus is hotter than the surface of Mercury because ...

Venus is more massive and is able to retain a thick atmosphere.

Which of the following is moving fastest in the orbit?

Venus at its perihelion (closest point to Sun)

Which of the following is FALSE?

Saturn has a density of 4.8 grams per cubic centimeter, similar to metals like aluminum and iron

Which of the following objects have a dark/black sky, even in the daytime?

both the Moon and Mercury

Which of the following is the largest distance?

the distance from Jupiter to Saturn

Where on the Venn diagram, above, does the clue "Tail always points away from the Sun" belong?

C (See practice questions)

Which of the following is NOT required in order to classify a Solar System object as a planet (instead of a dwarf planet)?

It must be larger than all of the moons in the Solar System

Which of the following planets looks the most like the Earth's Moon?

Mercury

Which is NOT a characteristic of a comet?

most orbit the Sun in between the orbits of Mars and Jupiter

Which of the following is the cause of an aurora?

Solar wind particles that hit the atmosphere of a planet

In the diagram above, which planets have temperatures lower than -200 degrees Fahrenheit?

all the Jovian planets (See practice questions)

Which planet is this in the picture? (to the right)

Venus (See practice questions)

The moon has about 1/100th the mass of Earth and 1/4 the radius. What is the surface gravity of the Moon compared to the Earth?

16/100

What did Newtons law of Universal Gravitation tell us about how gravity works?

The force of gravity from the Sun will be stronger on a larger mass object

According to Newton's second law of motion, if the net force acting on the object increases while the mass of the object remains constant, what happens to the acceleration?

acceleration increases

Longest day of the year in the northern hemisphere

June 21

Shortest day of the year in the Northern Hemisphere

December 21

What time of year is it dark all day (and night) at the South pole?

June

Earth's Moon was Full on May 1, 2007. When was it next in the First Quarter phase after this Full Moon?

May 22

A moon orbits a planet in exactly the same plane as the planet orbits its star. How often does this planet experience a solar eclipse?

Once every orbit of its moon (its month)

When is the best time for you to be able to see the constellation that is your sign of the Zodiac?

At midnight six months after your birthday

Constellations close to the North pole of Earth

Move in a circle around the North star, Polaris, over the course of a single night.

What is the relationship between wavelength and frequency?

If the frequency increases the wavelength decreases

Compare the frequency and wavelength of a gamma ray with that of visible light:

gamma ray frequency is higher and its wavelength is lower

Fill in the blank. A photon's _________ can be measured to determine its energy.

wavelength

Something glowing in visible light probably has a temperature of ___ Kelvin.

a few thousand

A star has a surface temperature of 50,000K. In which region of the electromagnetic spectrum does its peak brightness occur?

ultraviolet

The electrons in a cloud of hydrogen gas are making the transition from excited states to the ground state. What does the spectrum of this cloud of gas look like?

It will consist of a few bright emission lines at a very specific wavelength

Which of the following is FALSE?

The energy of a photon increases in proportion to the wavelength of the radiation.

How long would one need to observe a star on a 10 meter telescope to collect the same amount of light as one collects in one hour on a 5 meter telescope?

15 minutes

Even the largest ground-based telescopes have resolution restrictions imposed by:

atmospheric blurring of images

A ______ telescope uses ______ to focus light.

- refracting: lenses
- reflecting: mirrors

Two planets have the same mass, but Planet A has 3 times the radius of Planet B. How do the surface gravities of the two planets compare?

Planet a has 1/3 the surface gravity of Planet B

The surface gravity on Mars is 40 percent of the surface gravity on Earth. This means....

You can jump higher on Mars than on Earth

Which of the following Solar System objects has the strongest surface gravity?

Jupiter

When are the days and nights of equal length?

March 21 in both hemispheres

When are the nights longest compared to the days?

June 21 in the Southern hemisphere

Which would have the shortest day and longest year?

A planet that rotates rapidly on its axis and orbits slowly around the Sun.

Two weeks after the Third Quarter Moon it is the

first quarter moon

When does the New Moon set?

sunset

What passes in front of the Sun during a Solar eclipse viewed from Earth?

the Moon

what time is the waxing crescent moon directly overhead

3 pm

What is the name of the path of the Sun through the sky relative to the distant stars, as viewed from Earth over the course of the year?

ecliptic

For a star close to the North star, how long does it take to move in a circle the whole way around the North star?

24 hours

How often is the Sun in front of a Zodiac constellation?

always

Which of the following is FALSE?

A higher temperature blackbody peaks at a longer wavelength than a lower temperature blackbody.

Of the following types of radiation, which has the highest frequency?

X-rays is greater than radio waves, infared, UV, and visible

Lower-energy radiation has

longer wavelengths

What happens when an atom absorbs photons of certain energies from a background continuum source?

Dark lines arise in a spectrum

In the spectroscopy game, what did you do to produce a continuous spectrum with a bluer color?

raised the temperature of the lamp

In the spectroscopy game, after you zoomed in on the atoms, how did you decide what atom to click on to produce a certain emission line in the spectrum?

you matched the energy with the energy emitted when electrons jumped from high to low energy levels

What is a continous spectrum?

light at all wavelengths

What kind of light does not get through Earth's atmosphere?

X-ray

How much more light does a 12 meter telescope collect than a 6 meter telescope?

4 times more

A reflecting telescope collects light

in proportion to the area of its mirror

According to Newton's Second Law of Motion, if the next force acting on the object increases while the mass of the object remains constant, what happens to the acceleration?

acceleration increases

If the Earth were moved to half its current distance from the Sun, how would the force of gravity by the Sun on the Earth change?

It would become fours time stronger

What did Newton's Law of Universal Gravitation tell us about how gravity works?

The force of gravity from the Sun will be stronger on an object with more mass.

The Earth radius is about 6400 km. If you were in orbit in the Space Station 150 km above the ground, the force of gravity you feel from Earth would be:

Slightly weaker than when you are standing on Earth

If you were to sit on the ground, there would be a force due to gravity pulling you toward the Earth. Which of the following is true according to Newton's 3rd Law?

You are pushing the Earth away from yourself with the same force

What would happen to Earth if the Sun's gravity somehow 'turned off' instantaneously?

It would continue to move in a line in the same direction it was moving when the gravity turned off.

Consider a planet whose rotation axis is NOT tilted with respect to its orbital plane. What are the seasons like on this planet?

there are no seasons