LAUSR

Abstract Methods of measuring distances to distant objects, allowing to investigate structure of our Milky Way, are briefly discussed. The methods may be based on three principles: using standard rod, standard candle and column density of interstellar matter. Using of the first one is generally restricted to pretty nearby objects. The third one can be applied in the thin galactic disc only. The spectrophotometric method (standard candle) is the most universal one but it involves uncertainties related to calibration the “standard candle” parameters and the interstellar extinction effects. Weak and strong points of these three methods are presented. The presence of gray extinction towards some objects is suggested which makes the most universal method of standard candle very uncertain. It’s difficult to say whether this extinction appears in the form of circumstellar debris discs or is present in the general interstellar medium. The application of the method of measuring column densities of interstellar gases suggests that the rotation curve of our Milky Way system is rather Keplerian than flat which creates doubts to whether any Dark Matter is present in our Galaxy. It is emphasized that the most universal method, i.e. that of standard candle, used to estimate distances to cosmological objects, may suffer serious errors because of improper subtraction of extinction effects.