An astronomer see a star that is very far away but still very bright. what can she conclude about the star?

the star must be very large.

the star must be very small.

the star must be moving away from earth.

the star must be moving closer to earth.

The correct answer is The star must be very large.

The visibility of a star totally depends on its brightness and luminosity. The star can be easily seen because it is very large in size. The light emitted from the star is visible only because the size of the star is very large as compared to that of other stars present in sky. For example: if you compare a headlight of a car and flashlight of the mobile phone which are kept 10 feet away from the observer. The headlight of car is easily visible as compared to that of flashlight because is it bigger in size and hence its brightness and luminosity will be more as compared to that of flashlight.