Chronos said:
..by yardsticks, you mean, comparison to solar system scales??Scientists use a variety of techniques to measure the distance to stars and galaxies, including parallax, spectroscopic parallax, and the cosmic distance ladder. Parallax involves measuring the apparent shift in a star's position when viewed from different points in Earth's orbit. Spectroscopic parallax uses the Doppler effect to measure the distance to stars based on their spectral lines. The cosmic distance ladder combines various methods, such as using variable stars and supernovae, to calculate distances to galaxies.
Measuring the distances to stars and galaxies allows us to understand the vastness of the universe and the scale of celestial objects. It also helps us determine the age and evolution of the universe, as well as the properties of various celestial bodies such as stars, galaxies, and clusters.
One of the main challenges is that the vast distances involved make it difficult to accurately measure the parallax or other methods used. Additionally, there can be errors in the instruments used or the assumptions made in the calculations. The distances to some objects, such as galaxies, are also constantly changing due to expansion of the universe, making it challenging to measure them accurately.
For objects that are too far away to measure directly, scientists use various techniques such as standard candles or standard rulers. Standard candles are objects with known intrinsic brightness, such as Type Ia supernovae, that can be used to determine their distance based on their apparent brightness. Standard rulers, such as the large-scale structure of the universe, can be used to measure distances based on known physical relationships.
Yes, measuring the distances to stars and galaxies helps us understand the origin of the universe in several ways. By measuring the rate of expansion of the universe and the distances to distant galaxies, we can determine the age of the universe and the timing of significant events such as the Big Bang. Additionally, studying the distribution of matter and the large-scale structure of the universe can provide insights into the early stages of the universe's formation.