The cosmos is vast, so how do we measure it?

image via New Scientist

July 9, 2025, 6:00 PM

• •The universe's vast distances challenge visualization.
• •Astronomers use a "ladder" of measurements, including Cepheid variables and supernovae, to gauge cosmic distances.
• •Space-time expansion causes redshift, stretching light and changing distance measurements.

The article explores the challenges of understanding and measuring the immense distances in the cosmos. It highlights the difficulty in visualizing these scales and the methods astronomers use, such as Cepheid variables and supernovae, to build a "ladder" of distance measurements. The concept of space-time expansion and its effects on distance measurements, including redshift, are explained, addressing how these factors influence our understanding of the universe's structure and evolution. The article also touches on reader inquiries about how these measurements are made and interpreted.

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