Astronomy Now Magazine

The October issue of Astronomy Now rewrites the history of Mars. For decades, we pictured the young Red Planet as a warm, wet world of rivers and lakes that gradually became the cold desert we see today. But a wealth of new evidence is revealing a far more complicated story. Elizabeth Howell explores our changing view of Mars and asks what really happened to the planet’s water, atmosphere and potentially habitable environments.

Back on Earth, how dark is your night sky? We show you how to put your own skies to the test, discover what the results reveal about light pollution and find out what you can do to help protect the night. Meanwhile, Colin Stuart takes a different tack and asks a deceptively simple question with profound implications for cosmology: why is it dark at night?

Elsewhere, cosmology has a problem. Different ways of measuring how fast the Universe is expanding stubbornly refuse to agree, even as the measurements themselves become increasingly precise. Thomas Villa explores the Hubble Tension and asks whether astronomers are still being misled by hidden uncertainties, or whether the discrepancy could be pointing towards a deeper rethink of our understanding of the Universe.

For observers, October brings the autumn skies into their own. Our Night Sky section guides you through the best sights of the month, including the beautiful Triangulum Galaxy, M33, for Smartscope users, while our practical project shows how you can put together a photographically fast telescope on a budget without sacrificing performance.

Plus, we bring you the latest astronomy and space news, equipment, imaging, books and stories from our community of readers.

Discover a new Mars, test your own night sky and explore the autumn Universe only in your October copy of Astronomy Now.