ScienceJuly 14, 2026

afterglow

/ˈæf.tɚ.ɡloʊ/

Definition

The lingering, detectable radiation or light remaining from a powerful event, specifically referring in cosmology to the thermal remnants of the Big Bang.

Etymology

The word is a compound of 'after' and 'glow,' appearing in English during the mid-19th century. It was originally used to describe the light remaining in the sky after sunset before being adopted into scientific terminology to describe residual energy or radiation.

In the news

The article uses the term to describe the 'cosmic microwave background radiation,' which is the residual energy still observable from the birth of the universe. Studying this phenomenon is a key focus of the Simons Observatory, highlighting the importance of private funding for fundamental science.

10 Philanthropic Funders Powering Space Science

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