Ask Astro | Astronomy.com

How can a black hole pull light into itself if a photon is massless?

NGC 253 in Sculptor

Astronomy for beginners, Observing

What are NGC objects, and where did this catalog come from?

How is TESS able to spot more planets in the sky than Kepler could?

three spectra

How does spectroscopy work?

Observing, Observing Basics

Why aren’t the constellations always drawn the same way?

V838 Monocerotis

What is a light echo?

Orion Nebula

Observing, Observing Basics

How do light pollution filters work?

LHC at CERN

Is there a hottest temperature possible in the universe?

galaxy cluster Abell 2744 as seen by JWST and the Chandra X-ray Observatory

Cosmology, Exotic Objects

Astronomers say they’ve spotted the oldest, most distant black hole. How do they know this?

Hubble image of variable star RS Puppis

How do Cepheid variables indicate distance?

Exotic Objects, Solar System

What are the chances of dark matter or a black hole ripping apart Earth?

The Moon rises over mountains in Utah. Credit: NASA/Bill Dunford.

Science, The Moon

Why does the Moon look so large sometimes as it rises on the horizon?