cloudynights.com
Unknown
Cloudy Nights is a comprehensive online community for amateur astronomers, offering equipment reviews, user forums, observing reports, and tutorials on telescopes, mounts, accessories, and astrophotography.
More resources on Observational Astronomy
Sky Tour
When you head outdoors tonight, take Sky & Telescope's Sky Tour astronomy podcast with you for a guided tour to the night sky. Learn what constellations are visible, find out where and when you'll see the planets, and catch each month's celestial highlights, from meteor showers to eclipses.
stellarium.org
Stellarium is a free, open-source planetarium software that renders realistic night skies—stars, planets, constellations, and deep-sky objects—for any date, time, and location. The site offers downloads for multiple platforms and extensive documentation, tutorials, and examples to help you explore and learn astronomy.
Astronomy: Exploring Time and Space
This course is designed for anyone who is interested in learning more about modern astronomy. We will help you get up to date on the most recent astronomical discoveries while also providing support at an introductory level for those who have no background in science.
Astronomical Observations
Cambridge text on the optical instrumentation behind astronomical measurement: telescopes, detectors, spectrographs, photometry and the treatment of noise. After it you can judge how an observation is made and where its uncertainties come from.
The Backyard Astronomer's Guide
Reference manual for amateur observers, covering telescope and binocular selection, eyepieces, star atlases, and observing techniques. Readers finish able to choose equipment sensibly and plan sessions on the Moon, planets, and deep-sky objects.
in-the-sky.org
In-The-Sky.org is an astronomy resource for skywatchers, offering current and future celestial events along with ephemerides and practical observing data—planetary positions, Sun/Moon data, rise/set times, and calendars for eclipses, meteor showers, and other phenomena.