Astro final review

By studying distant galaxies in the 1920s, Edwin Hubble made the following discovery that led us to conclude that the universe is expanding

All galaxies outside of the Local Group are moving away from us, and the farther away they are, the faster they are going.

Suppose that we use a baseball to represent Earth. On this scale, the other terrestrial worlds (including Mercury, Venus, the Moon, and Mars) would range in size approximately from

a golf ball to a baseball.

T/F: Einstein could have predicted that the universe is expanding 10 years before this was discovered.

True

What do astronomers mean by the "Big Bang"?

The event that marked the beginning of the expansion of the universe

Considering all of its characteristics, PLUTO is most similar to which of the following groups?

The Oort-Cloud Comets

What is Einstein's "Equivalence Principle"?

The idea that the effect of gravity is exactly equivalent to the effect of acceleration and the idea that if you are locked inside a room without any windows, you can't tell the difference between a force of gravity and a rocket causing the room to accelerate upwards.

Which of the following is the most common type of object found in our Solar System? That is, which of the following has the greatest number in our Solar System?

Comets

When you look up at the constellation Orion and you find the Orion Nebula in Orion's sword, you are

looking at light that is affected by gas and dust in outer space as well as light emitted by very young stars and gathering information from the time of the Roman Empire

Which of the following statements about comets is NOT true?

Comets are giant balls of gas like the Jovian planets.

Asteroids are predominantly found in

The asteroid belt and Two locations on Jupiter's orbit (one ahead of Jupiter and one behind Jupiter)

If we imagine the history of the Universe compressed into one year, then Kepler and Galileo did their work about

1 second ago

What is "Ceres"

The first (and largest) asteroid that humans discovered (in the early 1800s)

Why did astronomer Carl Sagan (the person who did the original "COSMOS" series on TV) say that we are all "star stuff"?

Near every atom from which we are made was once (before the Solar System formed) deep inside of a star.

One astronomical unit is the

average distance between the Sun and the Earth.

What quantity is always constant in Einstein's "Special Theory of Relativity" according to any observer looking at any reference frame?

The speed of light

Which of the following astronomical observations or experiments provided evidence supporting Einstein's "General Theory of Relativity" ?

Observations of the positions of stars during the Solar Eclipse of 1919 by Arthur Eddington

Which of the following objects was declared to be a "planet" when it was originally discovered but was later reclassified as a different type of object?

Ceres

who developed the theory of gravitational lensing?

Albert Einstein

This image was recently recorded with the Euclid Space Telescope launched by the European Space Agency (ESA).

What type of object is outlined with a solid yellow line (labeled with letter B)?

A spiral Galaxy

This image was recently recorded with the Euclid Space Telescope launched by the European Space Agency (ESA).

What type of object is outlined with a dashed white line (labeled with letter A)?

An Elliptical Galaxy

This image was recently recorded with the Euclid Space Telescope launched by the European Space Agency (ESA).

Box C showed a zoomed-in image of the center of this object. Here we see an excellent example of

gravitational lensing

How much energy would be released if we could completely convert the mass of a 1.00 kilogram rock into energy? Joules

Note: a "Joule" is a unit of measurement of energy that is used in the metric system. To get the correct answer, you must use other units of the metric system such as meters or kilograms.

To give us a sense of how much energy this is, let's convert the answer to a different unit that is used to measure energy called the "megaton". One "megaton" is the amount of energy released by the detonation of 1 million tons of dynamite.

One megaton is equal to 4.0 x 10¹⁵ Joules.

How many megatons of energy would be released by the conversion of this rock into energy?

1. 9E16

2. 22.5 megatons

Suppose you are in outer space observing two other spaceships that are moving at close to the speed of light, which we refer to as 'c'. The pilot of one ship is your friend Jackie, and the pilot of the other ship is Bob. If you see Jackie moving away from you to your left at exactly 0.99c and Bob moving away from you to your right at exactly 0.99c, Jackie will say that Bob is

going away at faster than 0.99c, but slower than c

Light normally travels at 300,000 km/s. If a futuristic cyber train moving east at 200,000 km/s turns on its front searchlight, the light will travel at

300,000 km/s because The speed of light is always measured to be 300,000 km/s regardless of the speed of the observer or the speed of the light source

Which of the following is NOT true of Special Relativity: 1. the theory is valid only at speeds close to the speed of light 2. The theory gives the same answer as Newtonian physics at speeds much smaller than c 3. The theory describes only objects moving at constant speeds and in constant directions 4. The theory destroys the classical notion of absolute time and space

1. the theory is valid only at speeds close to the speed of light

a spaceship leaves Earth and attains a speed that is almost as fast as the speed of light, someone who stayed behind on Earth will observe that

the clocks on board the spaceship are running slow, the spaceship has become incredibly massive, and the ship is squashed down in the direction of motion, i.e., it is shorter than it was when it took off

What is "the equivalence principle"?

It is the basic idea that enabled Einstein to develop The General Theory of Relativity and it is the idea that gravity is the same as an accelerating reference frame

Jordan is racing a light beam in a 100-meter dash. Jordan bursts out of the starting blocks at 99% of the speed of light (0.99c). At the same instant, a flashlight beam is turned on from the starting blocks.
According to the spectators watching in the stands, what happens?

The light beam wins the race, but just barely since it is moving only 1% of the speed of light faster than Jordan.

Jordan is racing a light beam in a 100-meter dash. Jordan bursts out of the starting blocks at 99% of the speed of light (0.99c). At the same instant, a flashlight beam is turned on from the starting blocks.

According to JORDAN, what happens?

The light beam moves out ahead of Jordan at the full speed of light, winning the race easily

This person developed a system for predicting planetary positions that remained in use for some 1500 years. Even though his model was ultimately shown to be wrong, it was favored for 1500 years because it made fairly good predictions.

Ptolemy

As viewed from Earth, the "Milky Way" is best described as

The patchy band of light that we see when we look into the plane of our Galaxy.

One reason the ancient Greeks rejected the idea that the Earth moves around the Sun was that they

could see no shift in positions of nearby stars compared to distant stars (parallax) over the course of the year.

Earth reaches aphelion in July and perihelion in January.
During which northern hemisphere season is Earth moving fastest in its orbit?

Winter

Which of the following was not observed by Galileo?

Stellar Parallax

What did Galileo observe?

Four moons orbiting Jupiter, the phases of Venus and Mountains and Valleys on the Moon

Ideas attributable to the Greek philosopher Democritus

The idea that at some level matter is composed of tiny indivisible units called ‘atoms’, The system of governance known as ‘democracy’, the hypothesis that the Milky Way is composed of a huge number of individual stars

What is the ultimate source of energy in the Sun

The mass energy of hydrogen fusing into helium

An atom that has fewer electrons than protons is called

an ion

What is an isotope?

forms of the same element with equal numbers of protons but different numbers of neutrons

What is NOT a direct consequence of Kepler’s Laws?

The force of attraction between any two objects decreases with the square of the distance between their centers.

What does Atomic nuclei consist of?

Protons and Neutrons

How much electrical charge does an atom with 6 protons, 6 neutrons, and 5 electrons have?

a positive charge of + 1

What is the small angle formula and when do you use it?

To find linear diameter you use the small angle formula, which is Distance x Angular diameter

The amount of gravitational potential energy released as an object falls depends on

its mass and the distance that it falls.

Which object has the most KE (kinetic energy)? 1. A 1-ton car moving at 50 km/hour 2. A 10-ton boat moving at 10 km/hour 3. A 2-ton car moving at 50 km/hour 4. A 1-ton car moving at 100 km/hour

4 - A 1-ton car moving at 100km/hour

T/F: The Milky Way can only be seen from the Northern Hemisphere

False

T/F: The atomic nuclei of the same element always have the same number of neutrons

False - they always have the same number of Protons

What is the ecliptic plane?

The plane of the Earth’s orbit around the Sun

What is true about the celestial equator at all latitudes?

At all latitudes the celestial equator represents the extension of the Earth’s equator onto the celestial sphere

What is the point directly over your head called?

The Zenith

The Moon's orbital period (29.5 days) is the same as its rotational period, i.e., the Moon spins around once in the same amount of time that it takes to orbit around the Earth once. Now suppose that the Earth's rotational period were also 29.5 days (i.e., it would take 29.5 days for the Earth to spin around once). In this situation:

The Moon would always be in the same place in the sky, and it would never rise or set

One astronomical unit is the

average distance between the Sun and the Earth.

Eclipses of the Sun and the Moon do not occur every month because

the Moon's orbit is inclined (tilted) by 5 degrees relative to the ecliptic plane. (The "ecliptic plane" is that plane of the Earth's orbit around the Sun.)

True or False: the system that astronomers use for mapping the locations of objects in the sky is very similar to the system that we use to map the locations of objects on the surface of the Earth.

True

T/F: constellations are an important part of modern astronomy

false - constellations are a mostly historic artifact that are occasionally referred to by astronomers to specify a star’s location

Jupiter is about 5 times farther from the Sun than the Earth is. If the angular diameter of the Sun is about 0.5 degrees as seen from the Earth, then how many degrees wide is the Sun as seen from Jupiter?

0.1 degrees

Which of the following corresponds to the ‘dark side’ of the Moon: New Moon, First Quarter, Full Moon, Third Quarter, or None of the above

None of the above - dark side of the moon = far side of the moon that we never seen

What is the linear diameter of the Moon? (ang. diameter = 0.009, distance = 4000,000km)

3,600km

What principle does a movie theater work on?

Diffuse reflection

In this image of the Earth taken by the ISS (international space station) which feature shows an example of specular reflection?

Feature C

What physical process causes the Moon to turn red during a total lunar eclipse?

Diffuse light reflection (aka light ‘scattering’) and Light refraction

If you travel north from the US into Canada, how will Polaris (the North Star) change?

It will be higher in the sky

Most stars rise and set, but some never rise or set (the circumpolar stars). Is this statement universally true for any observer on Earth?

No, there are two places on Earth where none of the stars rise and set

T/F: the seasons are caused by the changing distance from the Earth to the Sun as the Earth moves in its orbit

False - seasons are caused by the earth’s tilted axis

Which planet would be the best choice for precision parallax measurements?

Neptune - the parallax anger is larger and easier to measure

Which property of the comet did Brahe use to prove that it is farther away than Aristotle claimed?

The parallax of the comet

At aphelion does a planet move faster, slower, or at the same speed as it does at perihelion

Slower

Where are most asteroids located

between Mars and Jupiter

If an asteroid has an average distance of 3AU from the Sun, how long does that asteroid take to orbit the Sun (approximately)?

5 years

What is heat a measurement of

Kinetic energy

What is thermal energy

the collective kinetic energy of the many microscopic motions of particles within a substance

A Sun-like star puts out 9 × 10²6 Joules every second. The speed of light is 3 × 10^8 m/s. How much mass does the star convert to energy every second?

10^10kg

Light is a form of energy. Like particles, light comes in individual "pieces" called photons. When an atom absorbs a photon containing energy, any of the following can happen except which?

An electron moves from a higher energy level to a lower one.

When an atom loses an electron, it becomes

ionized

At extremely high temperatures (e.g., millions of degrees), which of the following best describes the phase of matter?

a plasma consisting of positively charged ions and free electrons

Light waves differ fundamentally from sound waves because

light waves can travel in a vacuum, i.e., light waves do not need a "medium" such as water or air to travel through

The frequency of a wave is

equal to the speed of the wave divided by the wavelength of the wave, measured in Hertz (Hz) or measured in cycles per second, the number of wave peaks passing by any point each second

T/F: Some radio waves can be as long as a football field

True

Light from a distant star can be divided into a spectrum by using a glass prism or

a diffraction grating

f you are given the frequency of the photon, you can also determine its

wavelength

Which moves the fastest: Blue light, Red light, or Gamma Rays

None of the above, all light travels the same speed regardless of its wavelength

Which of the following correctly orders the radiation of the electromagnetic spectrum by wavelength?
(from large to small)

radio, infrared, visible, ultraviolet, x-ray, gamma ray

formula for electromagnetic radiation

λ = c/f. λ= wavelength c = speed of light. f = frequency

If two opaque objects are the same size but one object is 3 times hotter than the other one, then the hotter object emits

81 times more energy

Hotter objects emit photons with a higher average

frequency

The star Sirius has a surface temperature of about 12,000 Kelvin, whereas our Sun has a surface temperature of about half that value. How much more total energy output per unit surface area does Sirius give off?

16 times

Betelgeuse is a red giant star in the constellation of Orion. Compared to our Sun, Betelgeuse must be

cooler

A star with a continuous spectrum shines through a cool interstellar gas cloud composed primarily of hydrogen. The cloud is falling inward toward the star (and away from Earth). Which statement best describes the spectrum seen by an Earth-bound observer?

Red-shifted hydrogen absorption lines

Two stars are almost exactly the same, but Star A is rotating more rapidly than Star B. How will the widths of the spectral lines of Star A compare to those of Star B?

They will be wider

According to the nebular theory of solar system formation, what is the origin of the Oort Cloud?

The Oort Cloud is composed of planetesimals that formed in the outer Solar System that were flung into distant orbits by encounters with the Jovian planets.

Which of the following best describes the lunar MARIA?

Relatively smooth, flat plains on the Moon

The formation of planets begins with condensation: as gas cools, some atoms and molecules stick together and form tiny solid particles which we call dust grains. These dust grains, in turn, collide and stick together and eventually grow into planetesimals and even full-blown planets.

Which of the following elements and molecules would NOT condense and turn into dust grains in the protosolar nebula?

Hydrogen, Helium, Argon

What are the circumstances under which convection can occur in a substance?

The substance is strongly heated from underneath.

The basic idea at the core of the nebular theory of solar system formation is that

our solar system formed from the collapse of an interstellar cloud of gas and dust

What is the definition of the "frost line" in the context of solar system formation theory?

The frost line is the distance from the Sun beyond which the temperature in the protosolar nebula was low enough for ices to condense.

According to nebular theory, what are asteroids and comets?

They are leftover planetesimals that never accreted into planets.

What do we mean by the period of "heavy bombardment" in the context of the development of our solar system?

The first few hundred million years after the planets formed, which is when most impact craters were formed

According to modern scientific dating techniques, approximately how old is the solar system?

4.6 billion years

Which of the following best explains why the vast majority of the mass of our solar system consists of hydrogen and helium?

Hydrogen and helium are the most common elements throughout the Universe because they were the only elements that were formed when the Universe was extremely young. All other elements were subsequently synthesized inside stars, which is an inefficient process

What is the primary basis upon which we divide the ingredients of the protosolar nebula into four categories (hydrogen/helium, hydrogen compounds, rock, and metal)?

The temperatures at which various materials will condense from gaseous form into solid form.