Quasars and Redshifts

What then were these “quasi-stellar radio sources”? The name “quasars” started out as short for “quasi-stellar radio sources” (here “quasi-stellar” means “sort of like stars”). The discovery of radio sources that appeared point-like, just like stars, came with the use of surplus World War II radar equipment in the 1950s. Although few astronomers would have predicted it, the sky turned out to be full of strong sources of radio waves. As they improved the images that their new radio telescopes could make, scientists discovered that some radio sources were in the same location as faint blue “stars.” No known type of star in our Galaxy emits such powerful radio radiation.

• Quasars are quasi-stellar radio sources that appear point-like, similar to stars, and emit powerful radio waves.

• Quasars are a type of star in our Galaxy that emits powerful radio radiation.

• Quasars are radio sources discovered using World War II radar equipment that appear like faint blue stars.

In 1963 at Caltech’s Palomar Observatory, Maarten Schmidt was puzzling over:

• the nature of quasars

• the structure of DNA

• the theory of relativity

• the existence of black holes

What was the speed at which 3C 273 was receding from us, according to the Doppler effect?

• 50,000 km/s

• 16% the speed of light

• 100,000 km/s

• 10% the speed of light

Tags

NGSS.HS-PS4-1

The discovery of redshifts in quasars was significant because it provided evidence for what?

• The expansion of the universe

• The existence of dark matter

• The presence of black holes

• The formation of galaxies

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NGSS.HS-ESS1-2

The redshift of the first quasar showed that the light from it was:

• moving towards us

• stationary

• moving away from us

• changing color

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NGSS.HS-ESS1-2

The length of the jet from 3C 273 is:

• 100 light-years

• 1,000 light-years

• 10,000 light-years

• 100,000 light-years

Quasars appear star-like but are not actually stars because:

• they are distant galaxies with active nuclei.

• they are a type of neutron star.

• they are a type of supernova.

In the context of redshift, what does the symbol 'λ' represent?

• The symbol 'λ' represents the wavelength of light.

• The symbol 'λ' represents the frequency of light.

• The symbol 'λ' represents the speed of light.

• The symbol 'λ' represents the energy of light.

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NGSS.HS-PS4-3

NGSS.HS-PS4-1

Explain how the special theory of relativity affects the measurement of redshift for quasars and distant galaxies.

• The special theory of relativity causes time dilation, affecting the observed redshift.

• The special theory of relativity has no effect on redshift measurements.

• The special theory of relativity affects only the speed of light, not redshift.

• The special theory of relativity affects gravitational lensing, not redshift.

Suppose a distant quasar has a redshift of 3. At what fraction of the speed of light is the quasar moving away?

• 0.55c

• 0.66c

• 0.77c

• 0.88c