How did the measured diameter of Ceres evolve over time?
Which astronomers attempted to measure the diameter of Ceres, and what values did they find?
If astronomers can see an object as a disc instead of point of light, they can measure the apparent diameter of the disc.
For example, they can have thin wires stretched across the telescope at ...
I don't see a mention yet of variable stars.
There are stars whose brightness, as observed from earth, changes to an extent noticeable to naked-eye observers. The first two that we know historical people noticed provide examples of the two main types.
Algol, in the constellation Perseus, is an eclipsing binary where a dim companion periodically blocks some ...