• Home
• Tutorials
  • About these Tutorials
  • Glossary
  • Practical
    • Choosing a First Telescope
    • A Basic Eyepiece Set
    • Evaluating a Telescope
    • Polar Alignment
    • Basic Star Testing
    • Dealing with Dew
    • Colour Filters
    • Collimating a Refractor
    • Upgrading a 60mm Refractor
  • Optics
    • Telescope Function
    • How a Barlow lens Works
  • Astronomical Objects
    • Variable Stars
    • "Faint Fuzzies"
  • Mathematical Astronomy
    • Positional Astronomy
    • Time
  • Natural Phenomena
    • Tides
    • Twilight
    • Lunar Phases
  • Cosmology
    • Ancient Greek Astronomy
    • The Heliocentric Revolution
    • Stellar Evolution
    • The Scale of the Universe
• Pseudoastronomy
  • About Pseudoastronomy
  • "Apollo Hoax" Conspiracy
  • 2012 Nonsense
  • The May 2000 "alignment"
  • Uriel's Machine
  • Dos Santos Pyramidiocy
  • Hancock Astronomy
  • Silbury Orrery
  • False Retrodiction
  • Plumbing Parallel Universes
  • Flaws of Argumentation
• Writing
  • My Publications
    • Discover the Night Sky
      through Binoculars
    • Amateur Telescope Making
    • AstroFAQs
    • Binocular Astronomy
    • Small Telescopes
    • Amateur Spectroscopy
    • Articles, etc.
  • Book Shop
    • Beginners' Books
    • Charts, Atlases, etc.
    • Cosmology
    • General Astronomy
    • History of Astronomy
    • Mathematical Astronomy
    • Mythology of Astronomy
    • Practical Astronomy
    • Radio Astronomy
    • Telescope Making
    • Young Astronomers
• DIY Astronomy
  • Resources
    • Links
    • Software
    • Suppliers (UK)
    • Abrasive Size Comparison
  • Projects
    • Hand-driven Scotch Mount
    • Double-Arm Scotch Mount
    • 4" f/5.35 Reflector
    • 4" f/18 Refractor
    • Recce-camera Scope
    • Red-dot Finder
    • Simple Telrad Dewshield
    • Simple Quikfinder Dewshield
• Links
  • Astro Societies
  • Astro Organisations
  • Astro Education Resources
  • Near Earth Objects
  • Stuff in the Sky
  • Astro Software
• Talks & Courses
  • Talks
    • Astronomical Societies
    • General Audiences
    • Schools
    • Scouts, Guides, etc.
    • Bookings
  • Star-tales
  • Courses
    • 1-day Astronomy Workshop
    • Astronomy for
      Absolute Beginners
    • Start Stargazing
  • Contact

Dedicated to Outreach and Education in Practical Astronomy

The Astronomical Unit exists to make reliable astronomical information available to all. I do this through providing free information on this web site and undertaking outreach activities, including Star-tales (astronomy-based story-telling for children and adults), giving Astronomical Talks and running Astronomy Courses in the local community. These outreach activities are run both independently and in association with local astronomical societies, the National Trust, BBC Stargazing Live, local community groups, schools, colleges and adult learning centres.

I also run a companion website, The Binocular Sky, specifically for Astronomy with Binoculars.

lunar phases

Follow @AstUnit

Affiliation Disclosure
Stephen Tonkin is a participant in the Amazon EU Associates Programme, an affiliate advertising programme designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.co.uk.
Stephen Tonkin is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.
Stephen Tonkin is an affiliate of First Light Optics which provides a means for sites to earn commission by advertising and linking to firstlightoptics.com.