What physical quantity is used in astronomy to determine the distance to space objects? What is it equal to in SI units?

In astronomy, distances to space objects are often expressed in light years. 1 light year is the path traveled by light in one earth year; 1 eu, year = s * t = 3 * 10 ^ 8m / s * 365 * 24 * 3600 s = 9.46 * 10 ^ 15m.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.