List the features of astronomy as a science (give at least three options).

1) Astronomical observations in most cases are passive in relation to the objects under study; 2) many cosmic phenomena proceed so slowly that their observations would require enormous periods of time; 3) we observe the position of celestial bodies and their movement from the Earth, which itself is in motion – revolves around its axis and revolves around the Sun; 4) it is impossible to carry out repeated experiments (each observation is unique); 5) light from distant objects takes so long that we observe objects as they were in the distant past. (The order in which the features are listed can be arbitrary.)