Below is the table of contents for my free book, Introduction To The Cosmos:

History of Astronomy
__(there are several subsections here)
How The Universe Came Into Being
__(there are several subsections here)
Understanding the Constellations
__(there are several subsections here)
A Tour of Some Constellations Finding Things In The Sky
____Understanding Azimuth and Altitude
____Understanding Latitude and Longitude
____Understanding the Celestial Sphere
____Understanding Reference Points
____Horizon and Zenith
____Understanding Right Ascension and Declination
Understanding Telescopes and Cameras
____Understanding Optical Telescopes
____Understanding Light-Gathering Power
____Understanding Resolving Power
____Understanding Atmospheric Blurring
____Understanding The Different Types of Optical Telescopes
____Understanding Cameras
____Understanding Filters
Understanding What’s In Space
__ Understanding The Solar System
__ Understanding Stars
____Understanding Our Sun
____Understanding the Lives of Stars
____Understanding Main Sequence Stars
Understanding Galaxies
____Spiral Galaxies
____Elliptical Galaxies
____Lenticular Galaxies
____Irregular Galaxies
____Active Galaxies and Clusters of Galaxies
____Galaxy Collisions
Understanding Nebulae
____Interstellar Medium
____Understanding Types of Nebulae
Observing The Sky
____Getting Started With Imaging
________Using the MicroObservatory
____________Accessing Your and Others’ Images
____________Viewing and Editing Images
________Getting Started Using
________Getting Started Using
____Observing The Sky
_____Getting Started With Online Imaging
_____Using the MicroObservatory
_______Advanced Image Acquisition
__Planning Your Observations
_____Online Planning Using Telescopius
_____Planning Using Planetarium Software
__Image Processing
_____Sample Observation Download
_____Introduction To Image Processing Software
_____Processing Image Files Using
_____Processing FITS Files Using JS9
_______Combining 3 Luminance Images Into One Image
_____Processing FITS Files Using PixInsight