How can the transit method reveal a planet around another star?
A A change in Earth’s tides
B A flash from the planet
C A shift in the Moon
D A small dip in starlight
A planet crossing in front of its star can cause a small, repeating dip in the star’s measured brightness.
What does the radial-velocity method look for in a star?
A A small back-and-forth wobble
B A permanent color change
C A new ring system
D A sudden explosion
An orbiting planet’s gravity makes its host star move slightly, producing a measurable Doppler shift.
What does astrometry measure when searching for exoplanets?
A A planet’s surface color
B A star’s changing position
C A star’s radio sound
D A comet’s tail length
Astrometry tracks tiny changes in a star’s position on the sky that can be caused by an orbiting planet.
How does stellar parallax help estimate a nearby star’s distance?
A It counts its planets
B It measures its age directly
C It measures its apparent shift
D It records its radio pulses
As Earth moves around the Sun, a nearby star appears to shift slightly against much farther background stars.
What does spectroscopy study in the light from a star?
A Its surface texture
B Its orbit only
C Its separated wavelengths
D Its number of moons
A spectrum spreads light by wavelength and contains clues about a star’s temperature, motion, and chemical elements.
Compared with a cool red star, a blue star usually has what surface temperature?
A Lower temperature
B The same temperature
C Higher temperature
D No measurable temperature
A star’s color is related to its surface temperature; blue stars are generally hotter than red stars.
A blueshift in a star’s spectrum usually means the star is doing what relative to us?
A Moving away from us
B Moving toward us
C Not moving at all
D Orbiting the Sun
Light from an approaching source is shifted toward shorter, bluer wavelengths.
What is a binary star system?
A One star with two planets
B Two stars orbiting a shared center
C Two galaxies touching
D A star with two rings
In a binary system, two stars orbit their common center of mass.
What makes a star a variable star?
A It has no gravity
B Its brightness changes over time
C It has no light
D It never changes position
A variable star has brightness that changes, regularly or irregularly, over time.
Why are Cepheid variable stars useful for measuring distances?
A They are always closest to Earth
B They do not change brightness
C Their pulse period relates to true brightness
D They orbit the Milky Way once a year
The pulsation period of a Cepheid is linked to its intrinsic brightness, helping astronomers estimate distance.
What is a pulsar?
A A young gas planet
B A rapidly spinning neutron star
C A quiet white dwarf
D A cluster of comets
A pulsar is a rapidly rotating neutron star whose beams can sweep past Earth like pulses.
What distinguishes a magnetar from most neutron stars?
A Its extremely strong magnetic field
B Its visible rings
C Its low density
D Its orbit around Earth
A magnetar is a neutron star with an exceptionally strong magnetic field.
What is a quasar?
A A small rocky moon
B A dark nebula
C A very bright active galaxy core
D A nearby star cluster
A quasar is the extremely luminous central region of an active galaxy.
What is an accretion disk?
A Material orbiting and falling toward a compact object
B A flat ring around every planet
C A shell around a nebula
D A group of distant galaxies
Gas and dust can form a rotating disk as they move toward a compact object such as a black hole.
What does “interstellar medium” mean?
A Matter between stars
B Matter inside a planet
C Light between galaxies
D Dust on a telescope mirror
The interstellar medium is the gas, dust, and other material found in the space between stars.
Why does an emission nebula glow?
A It reflects only moonlight
B It is made of solid rock
C It is a group of planets
D Its gas is energized by nearby stars
Hot nearby stars can energize or ionize gas in an emission nebula, making the gas emit light.
What does a reflection nebula do with nearby starlight?
A Absorbs every wavelength
B Creates new stars instantly
C Scatters and reflects it
D Turns it into radio waves
Dust in a reflection nebula scatters and reflects light from nearby stars.
Why can a dark nebula look like a dark patch?
A Dust blocks light from objects behind it
B It contains no matter
C It emits only green light
D It is outside every galaxy
Dense dust in a dark nebula can block visible light from brighter objects behind it.
What two properties are commonly plotted on a Hertzsprung–Russell diagram?
A Mass and distance
B Age and orbit
C Color and number of moons
D Luminosity and temperature
The H–R diagram compares stars’ luminosities with their surface temperatures or related color classes.
Which spectral class contains the hottest ordinary stars?
A M type
B O type
C K type
D G type
O-type stars have the highest surface temperatures among the main stellar spectral classes.
What is the solar wind?
A A flow of water on the Sun
B A cloud of dust from Earth
C A beam of visible light
D A stream of charged particles from the Sun
The solar wind is a continuous flow of charged particles released by the Sun.
What is the heliosphere?
A A bubble shaped by the solar wind
B The Sun’s solid surface
C A ring around Saturn
D A group of nearby stars
The solar wind creates a large bubble around the Sun called the heliosphere.
In which general direction does a comet’s tail point?
A Toward the Sun
B Away from the Sun
C Toward Earth only
D Along its orbit always
Solar radiation and the solar wind push comet material so its tail points generally away from the Sun.
What is Sagittarius A*?
A A bright star near the Sun
B A nebula in Orion
C A planet beyond Neptune
D A supermassive black hole at the Milky Way’s center
Sagittarius A* is the supermassive black hole at the center of the Milky Way.
What is a protostar?
A A star that has become a planet
B A star cluster’s center
C A forming star before stable hydrogen fusion
D A cloud left by a comet
A protostar forms as a cloud of gas collapses, before the star settles into stable hydrogen fusion.
Which description best fits a globular cluster?
A A dense, roughly spherical group of old stars
B A ring of icy bodies
C A cloud between galaxies
D A pair of orbiting planets
Globular clusters are dense, roughly spherical collections of many old stars.
What does the term “supergiant” describe?
A A tiny cold asteroid
B A small type of galaxy
C A moon with an atmosphere
D A very large, luminous star
Supergiants are stars with very large sizes and high luminosities compared with ordinary stars.
What is the Sun’s corona?
A Its outer atmosphere
B Its central core
C Its visible surface
D Its orbit around Earth
The corona is the Sun’s outer atmosphere, extending far beyond the visible surface.
What is a gamma-ray burst?
A A slow radio signal from Earth
B A type of planetary ring
C A brief, intense flash of gamma rays
D A steady glow from the Moon
Gamma-ray bursts are brief, intense flashes of high-energy gamma-ray radiation from distant cosmic events.
What is a cosmic ray?
A A ray of sunlight reflected by Earth
B A visible line between stars
C A wave made by ocean tides
D A high-energy particle traveling through space
Cosmic rays are energetic particles that travel through space and can reach Earth.