astrobiology multiply choices

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Which best describes the "gravitational lensing" technique for finding exoplanets?

Group of answer choices

a massive object magnifies and distorts the light from an object behind it

the wavelengths of light from a star are shifted as it moves about its center of mass

a planet passes in front of its parent star and blocks part of its light

a massive object accelerates another object that passes close to it

 

Flag question: Question 2

Question 22.22 pts

Direct imaging generally can only detect what kind of exoplanets:

 

 

Group of answer choices

small and at great distances from their parent star

very large and at great distances from their parent star

very large and close to their parent star

small and close to their parent star

 

Flag question: Question 3

Question 32.22 pts

The RV (radial velocity) involved creating a graph of the star's radial velocity vs what other parameter?

 

Group of answer choices

radial velocity against time

radial velocity against luminosity

radial velocity against brightness

radial velocity against distance

 

Flag question: Question 4

Question 42.22 pts

When star moves away from us, the wavelengths of the starlight:

Group of answer choices

are the same as if the star were not moving

are shorter than if the star were not moving

can be longer or shorter depending on the distance to the star

are longer than if the star were not moving

 

Flag question: Question 5

Question 52.22 pts

Identify the method that is generally used to determine the diameter of an exoplanet?

 

Group of answer choices

detection of brightness changes in a star as a planet passes in front of it

detection of reflected starlight

detection of Doppler shifts in the spectra of the parent stars

regular changes in the positions of the parent stars with respect to more distant stars as they move across the sky

 

Flag question: Question 6

Question 62.22 pts

Most exoplanets have been discovered using which method?

 

Group of answer choices

detection of brightness changes in a star as a planet passes in front of it

detection of Doppler shifts in the spectra of the parent stars

detection of reflected starlight

regular changes in the positions of the parent stars with respect to more distant stars as they move across the sky

 

Flag question: Question 7

Question 72.22 pts

How do planet formation scientists explain so many Jupiter-mass planets found within 1 astronomical unit of their host star?

 

Group of answer choices

the Jovian planets formed farther out and then migrated inward

these are massive terrestrial planets that formed close to their parent stars

they are brown dwarfs that were captured by their parent stars

they are Jovian planets that were spun out from their rapidly spinning parent stars

 

Flag question: Question 8

Question 82.22 pts

Transits of an exoplanet across the stellar surface requires what condition:

 

Group of answer choices

planet has to be very large

parent star has to be very small

orbital plane of the planet has to be aligned along our line of sight

orbital plane has to be perpendicular to our line of sight

 

Flag question: Question 9

Question 92.22 pts

Astronomers find a planet a few time more massive than Earth and with an average density similar to rock. What do they call such an exoplanet?

 

Group of answer choices

super-Jovian

mini-Neptune

super-Earth

mega-Earth

 

Flag question: Question 10

Question 102.22 pts

The center of mass of Sun and Jupiter lies where:

Group of answer choices

just outside the orbit of Mercury

exactly at the center of the Sun

midway between the Sun and Jupiter

inside the volume of the Sun

 

Flag question: Question 11

Question 112.22 pts

An exoplanet is known to have a mass 2000x lower than its host star.  If the host star is measured to move around its center of mass every 10 years, what is the orbital period of the PLANET?

 

Group of answer choices

this cannot be determined from this observation

200000 years

20 years

10 years

1.8 days

 

Flag question: Question 12

Question 122.22 pts

Based on what we know about how stars age with time, which is most true?

Group of answer choices

the more heavy elements it contains

the faster it evolves

the slower it evolves

the more planets it has around it

 

Flag question: Question 13

Question 132.22 pts

Approximately how many confirmed exoplanets have been discovered ?

Group of answer choices

4000

100 billion

1000

100

 

Flag question: Question 14

Question 142.22 pts

The Doppler shift method has most difficulty detecting which kind of exoplanets?

 

Group of answer choices

a massive planet far from its parent star

a low mass planet far from its parent star

a low mass planet close to its parent star

a massive planet close to its parent star

 

Flag question: Question 15

Question 152.22 pts

When was first exoplanet found around a Sun-like star?

Group of answer choices

1990

2000

2005

1995

 

Flag question: Question 16

Question 162.22 pts

in 1974, Drake and Sagan sent a message to M13, a globular cluster about 20000 light-years away. When is the soonest we could receive a response from aliens there? 

Group of answer choices

20,000 years

80,000 years

40,000 years

10,00 years

 

Flag question: Question 17

Question 172.22 pts

What was the main reason the US Government spend resources to investigate UFOs after World War II?

 

Group of answer choices

were themselves developing new types of aircraft and used the official investigation as a cover-up

were afraid that an alien civilization was in the process of invading the Earth

thought that they might be new types of aircraft being developed by the Soviet Union

knew that UFOs were alien craft and used the official investigation as a cover-up

 

Flag question: Question 18

Question 182.22 pts

Why are scientists pessimistic about detecting signals from civilization in other galaxies?

Group of answer choices

signals from civilizations on other galaxies will not reach us before we give up listening

other galaxies are unlikely to harbor intelligent civilizations

signals from other galaxies will be severely weakened by distance, making them far harder for us to detect

they will most likely transmit at wavelengths that will be absorbed by intergalactic gas

 

Flag question: Question 19

Question 192.22 pts

Which is the best answer for how far we have searched for signs of alien radio signals used modern SETI? This includes signals stronger than just TV/radio leakage.

 

Group of answer choices

<10 light-years

>1000 light-years

the whole galaxy

few hundred light-years

 

Flag question: Question 20

Question 202.22 pts

Suppose that there are 1 billion (1,000,000,000,000) habitable planets in a nearby galaxy, that 1 in 5 habitable planets has life, that 1 in 1000 planets with life has at some point had an intelligent civilization, and that 1 in 1000 civilizations that have ever existed is in existence now. How many civilizations would exist at present?

Group of answer choices

2

200

20

2,000

 

Flag question: Question 21

Question 212.22 pts

In past studies, roughly 90% of UFO sightings

Group of answer choices

are hoaxes

can be explained by natural phenomena

are real sightings of alien craft

cannot be explained

 

Flag question: Question 22

Question 222.22 pts

Which statement best describes our confidence in results derived from the Drake Equation?

 

Group of answer choices

it is impossible for us to ever know the values of any of the factors

we have decent estimates for the first three factors, but not the last factors

we do not have good knowledge for any of the factors in the equation

we have an exact number for the first factor, but not for any of the other factors

 

Flag question: Question 23

Question 232.22 pts

We can crudely estimate the intelligence of extinct species using the Encephalization Quotient (EQ). How is the EQ for extinct species estimated?

Group of answer choices

extinct species always have the same EQ value

there is a linear relationship between the EQ and time, thus allowing extrapolation

we can estimate their body masses from their fossilized remains and their brain masses from the sizes of their fossilized cranial cavities

we can always find similar species in existence today to make measurements of

 

Flag question: Question 24

Question 242.22 pts

Optical lasers have been suggested as a means of alien communication.. What is one advantage of using lasers over radio ?

Group of answer choices

optical lasers can penetrate through dust better than radio waves

lasers can be focused into a tighter beam,wasting less energy during communication than radio waves.

lasers are easier to make than radio waves

There is nothing better about visible lasers compared to radio waves for communication

optical light is the only wavelength that can penetrate our atmosphere

 

Flag question: Question 25

Question 252.22 pts

Which kind of extraterrestrial signal would likely be the strongest and easiest to detect with our current technology?

 

Group of answer choices

a signal used for local communication in the world where the intelligent beings exist

an intentional signal beacon

a signal used for communication between a civilization's home world and another star system

a signal used for communication between a civilization's home world and another planet in its own planetary system

 

Flag question: Question 26

Question 262.22 pts

Which of the following is the least-serious difficulty associated with interstellar travel and a timely colonization of the galaxy?

Group of answer choices

the speed of light being the fastest possible speed we can travel

Time dilation and length contraction due to Special Relativity

the enormous amount of energy required to accelerate any ship to high speed

the huge distances between the stars

 

Flag question: Question 27

Question 272.22 pts

About how long would it take our fastest moving probes to travel the distance to the nearest stars?

Group of answer choices

about a 1,000 years

at least 100,000 years

around 4.4 years

several billion years

 

Flag question: Question 28

Question 282.22 pts

Given how many times intelligent civilizations could have appeared over the universe's history, it is most likely that if other civilizations exist, they will

Group of answer choices

have about the same level of technology as us

be slightly less advanced than us

be much more advanced than us

be much less advanced than us

 

Flag question: Question 29

Question 292.22 pts

What is the biggest limitation of using a solar-sail-propelled spacecraft to travel between stars?

Group of answer choices

low energy photons that the Sun produces

fact that the intensity of sunlight falls off rapidly with distance

gravitational force of the Sun

mass of the spacecraft

 

Flag question: Question 30

Question 302.22 pts

 Fermi Paradox could be resolved by all the following except:

Group of answer choices

no one is interested or able to communicate

intelligent species usually kill themselves off

we are not interested in communicating

no one is out there

we are unable to detect their communications

 

Flag question: Question 31

Question 312.22 pts

Which best describes the concept between a "wormhole"?

Group of answer choices

shortcut between two distant parts of the universe through spacetime allowed by Einstein's General Theory of Relativity

passageway to a parallel universe through a black hole explored by Einstein

way of traveling faster than the speed of light locally relative to the fabric of spacetime

shortcut between two distant parts of the universe through a black hole

 

Flag question: Question 32

Question 322.22 pts

How is the "Fermi Paradox" normally stated?

Group of answer choices

Who are we?

Why are we here?

Where are we?

Who are you?

Where is everybody?

 

Flag question: Question 33

Question 332.22 pts

A nearby exoplanetary system is approximately 9 light-years away. If we send a spacecraft to visit this system traveling at 90% of the speed of light, how long will a round trip take as measured from the Earth?  

Note: you don't need a fancy equation to solve this, just think which answer is most true based on the example of the twin paradox.

Group of answer choices

18 years

less than 18 years

about 20 years

it's impossible to tell unless we know the spacecraft's method of propulsion

 

Flag question: Question 34

Question 342.22 pts

In Einstein's Special Theory of Relativity, we observe time moving slower when an object travels at a speed near the speed of light.. This is called:

 

Group of answer choices

time dilation

a time warp

time expansion

time contraction

 

Flag question: Question 35

Question 352.22 pts

We can calculate the energy needed to accelerate a colony spaceship based on what:

 

Group of answer choices

its mass and final velocity

its final velocity only

the type of fuel it uses

its mass only

 

Flag question: Question 36

Question 362.22 pts

This question is similar to the one in the practice exam but with different numbers.

Using the radial velocity method, what is the maximum radial velocity amplitude (in METERS/SECOND) you can measure for a star with an earth-mass planet in a 2.0 year circular orbit around a 0.5 solar mass star?

For this problem, you can use the Earth weighs 1/333000 times the sun. 1 AU = 150e6 km

Give yours answer in meters/second with at least 2 sig digits.

 

Flag question: Question 37

Question 372.22 pts

If we consider the inner edge of the Habitable Zone to be 0.95 au today, where will it be when the Sun evolved to have a luminosity of 4x higher than today?

 

Flag question: Question 38

Question 382.22 pts

Astronomers discover a Sun-like star with transit depth f_dip = 0.0025 

What is the radius of this new planet  in units EARTH RADII?

 

 

 

Flag question: Question 39

Question 392.22 pts

The Earth orbits the Sun with a speed of about 30 km/s.  What speed does the Earth induce on the Sun, assuming the Sun is 333000 x more massive than the Earth?

Your answer should be  in units of METERS/SECOND :

use 2 significant digits or more

 

Flag question: Question 40

Question 402.22 pts

Consider a star that is half the size of the Sun.  How deep (in %) would a transit be for a planet that is the size of Jupiter?   Give your answer in terms of the percentage dip (not fraction).

 

Flag question: Question 41

Question 412.22 pts

A Jupiter-mass planet is observed by European Extremely Large Telescope orbiting a nearby star with period of 10 years with a semi-major axis of 10 au.  From this, we determine the mass of the host star to be what  (in units of solar masses)?

 

Flag question: Question 42

Question 422.22 pts

Astronomer's estimate the mass of the star 51 Peg to be 1.11 M_sun.  The planet 51 Peg b is observed to have an period of 4.23 DAYS.  Using Newton's version of Kepler's Third Law, what is the semi-major axis of the 51 Peg b orbit  in au (astronomical units):

[use 2 sig digits]