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.
One can conclude that the star is very bright. It usually also means large, but that is not always true on bright stars. However, of the choices, A is probably the best choice, but I suspect many astrophysicists would want to bite their tongue on such a simple answer, without noting the type of star also.
To conclude about the star based on the information given, we can use our knowledge about brightness and distance. The fact that the star is very far away but still very bright suggests that the star must be very large.
The intensity of light from a star decreases with increasing distance, meaning that the farther a star is, the dimmer it appears. However, if a star appears very bright despite being far away, it indicates that it must be emitting a large amount of light. In astronomical terms, larger stars generally produce more light due to their larger surface area and higher temperatures.
Therefore, we can conclude that the star must be very large based on its brightness despite being far away. The other options regarding the star's size, motion (moving away or closer to Earth), cannot be determined solely based on the given information.