MEDALS AND FAN
Why is it sometimes hard to determine the brightness of a star?

All stars are the same distance from the earth.
Not all stars are the same distance from earth.
The brightness of a star is not defined.
The brightness of star is dimmed by a telescope

Question

MEDALS AND FAN
Why is it sometimes hard to determine the brightness of a star?
 	
	All stars are the same distance from the earth.
	Not all stars are the same distance from earth.
	The brightness of a star is not defined.
	The brightness of star is dimmed by a telescope

anonymous · Answer

Well, A is definitely not true. C is not true because we can in fact define and calculate brightness (luminosity) of a star if we know the composition and distance. D could be true depending on the clarity of the lenses, but I don't think it wants us to go that far into detail.

I would say that it's B. It would be hard to determine the brightness of a star if we don't know the distance (or composition) from the Earth.

anonymous · Answer

for c, the brightness(luminosity) of a star can be calculated using a brightness scale which is calibrated with numbers.The smaller the number,the brighter the star and those with a value of 6 or below can be seen by naked eye.