Light Travel Time: How the Night Sky Shows Cosmic History
Why looking at distant stars and galaxies means observing light that began its journey long ago.
Astronomy archive
Dispatches from the universe
Six accessible, sourced explorations of distance, time, worlds, galaxies, and the signals we hope to find.
Reading an Exoplanet Atmosphere in Starlight
How transmission spectroscopy helps astronomers investigate the atmospheres of planets orbiting other stars.
The Speed of Light: A Cosmic Speed Limit
What the speed of light means, why a light-year measures distance, and how relativity changes journeys near the cosmic speed limit.
TON 618: Measuring an Ultramassive Black Hole
How astronomers infer the extraordinary scale of TON 618, a distant quasar powered by one of the most massive black holes observed.
The Andromeda Galaxy: Our Nearest Major Galactic Neighbor
What Andromeda's ancient light reveals—and why its future encounter with the Milky Way is now considered uncertain.
The Search for Intelligent Life: From Possibility to Evidence
How scientists search for technosignatures while separating intriguing possibilities from confirmed evidence.