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Astronomy Resources

Useful tools, calculators, and places to learn more about the night sky. Start with what helps you plan your next observing session, then return when you want to explore something new.

AstroGuy Calculators

Enter your equipment specifications to calculate eyepiece magnification, field of view, exit pupil, and focal ratio, or camera pixel scale and astrophotography field of view.

Sky Maps and Observing Planners

  • AstroChron — Astronomical events, planet and Moon information, and observing opportunities for your chosen location. Its planetary illustrations appear in the October AstroGuy observing article.
  • Stellarium — Desktop planetarium software for exploring constellations, objects, and the sky at a chosen date and time. Stellarium Web offers a browser option.
  • TheSkyLive — Object information, positions, and sky charts for planets, comets, and deep-sky targets.
  • Telescopius — Target planning and telescope/camera framing tools for astrophotography.
  • Mobile Observatory — A mobile astronomy tool for exploring the sky and planetary events. Check the current edition for features and requirements.

Weather and Observing Conditions

  • Clear Sky Chart — Astronomy forecasts for supported locations, including cloud cover, transparency, and seeing.
  • Weather Underground — General forecasts and local weather information to help plan a session.

Learn and Connect

More from AstroGuy

Find targets in this month’s observing guide, explore the Astrophotography gallery, or read observing stories and practical articles in AstroGuy’s Notebook.

Set the correct location, date, and time in planning tools. Features, pricing, and availability can change, so check each resource directly.

Enjoying AstroGuy?

If the observing guides, videos, articles, or astrophotography are useful to you, you can help support the website and keep AstroGuy growing by buying me a cup of coffee.

AstroGuy is independently produced. Support helps cover website hosting, equipment, software, and the cost of creating free astronomy content.

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