Why is the parallax method considered the 'first rung' of the cosmic distance ladder?

Answer

It establishes direct distance measurements for nearby stars, which calibrate secondary methods.

Parallax is the foundation because it provides direct, purely geometric distance determinations for local stars, allowing astronomers to calibrate methods needed for greater distances.

Why is the parallax method considered the 'first rung' of the cosmic distance ladder?

#Videos

The Ultimate Guide to Determining Star Distances: Methods Unveiled

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