PT7.S1.Q16 - Comets do not give off their own light

alexanderthegreat4-2-1-1

I do not understand why b is correct. Can someone help me understand why b is supported. Thank you for the help

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s_jricke

@alexanderthegreat4 said:
I do not understand why b is correct. Can someone help me understand why b is supported. Thank you for the help

Before we found out that Halley's comet was made up of certain type of material, scientists assumed that it took less mass to reflect a certain amount of light. Scientists then discovered that it takes more mass to reflect the light that they had been observing.

It is implied that scientists had underestimated the mass of Halley's comet because they were just wrong about how much light the material of Halley's comet reflects per unit of mass.

Think about if scientists used to think Halley's comet was made out of a super shiny material like aluminum or even a mirror. Now, think about if we found out that Halley's comet is made out of something was less reflective like wood (I know that sounds crazy but just follow me lol). The point is that once scientists found out that Halley's comet was actually made out of wood they would go, "woah, this thing must be bigger than we thought since it is made out of wood and still reflecting a brightness we assumed was for a much more reflective material like aluminum."

To reflect the same amount of light as something in spite of being made of a material that is less reflective per unit of mass, it must have a bigger mass.

alexanderthegreat4-2-1-1

Thank you for the help s_jricke !!