Astronomy Notes 2026 Edition

The following updates/revisions/additions were made for the 2026 hardcopy edition [the website is continually updated]:

  1. In chapter 1:  Added a list of websites and books about pseudoscience.
  2. In chapter 2:  Added more explanation about the peer review process and added a whole new section about Misinformation and Disinformation.
  3. In chapter 6: Edited the gravitational wave detectors section to improve clarity and updated information about future detectors.
  4. In chapter 8: Addition of James Webb Space Telescope and Nancy Grace Roman Space Telescope to space telescope material. Website has additional section about buying your own telescope.
  5. In chapter 9: Added paragraph about “planetary wind” atmosphere loss. Added paragraph about hotspot volcanism in the plate tectonics section. Added comment about possible Venus liquid water long ago. Updates to Mars' magnetic field, Mars and Jupiter interiors, and Jovian moons, especially Europa with Europa Clipper and possible plumes on Europa and new analysis of Cassini's observations of Enceladus. Revised formatting of Mars surface exploration to make it easier to read, updated Mars results to include new Curiosity and Perseverance's findings, as well as those from the orbiters, and added section in Mars about biosignatures of ancient life. Edited IPCC subsection of Earth–Human Role in Carbon Cycle section to improve clarity.
  6. In chapter 10: Results from the OSIRIS-REx mission to Bennu. Updates on Near-Earth Objects and Vera C Rubin Observatory's capabilities in finding asteroids and comets. Revised formatting of NEO section and Deflecting & Using Asteroids section to make them easier to read. Added results of the DART mission and New Horizons' flyby of Arrokoth. Updated comet water vs. Earth ocean water section, interstellar comets, and exoplanet discoveries (Kepler/K2 and TESS). Revised formatting of exoplanets section to make it easier to read. Added paragraph about transmission spectrum and direct source spectrum in the exoplanets section.
  7. In chapter 11: Added results from Gaia mission.
  8. In chapter 12: Added note about National Ignition Facility in nuclear fusion section.
  9. In chapter 13: Added note about Webb's view of the Carina Nebula in the protostar section. Added note about Pleiades tidal stream in the main sequence section. Corrected statement about Beryllium and Boron creation in stellar nucleosynthesis section. Added paragraph about rare white dwarfs that still have fusion happening. Added material about failed supernova and other ways to make a black hole. Updated LIGO/Virgo results about black holes.
  10. In chapter 14: Added a paragraph about Population III stars and updated the Galactic Center section, including EHT's image of Sagittarius A*.
  11. In chapter 15: Updated definition of galaxy to include dark matter and supermassive black hole. Added note about dwarf spheroidals in elliptical galaxies section. Revised formatting in Galaxy Masses section to make it easier to read. Added a subsection about the problems of short timescales and lack of intermediate-mass black holes in the Active Galaxies Powersource (supermassive black hole) section. Added a paragraph about the relationship between the masses of supermassive black holes and their host galaxies. There are updates about dark matter in galaxies (including dark matter free galaxies) and in galaxy clusters, Local Group membership, origins of galaxies, galaxy collisions & mergers, large scale structure (superclusters), supercomputer simulations of galaxy motions & evolution, HUDF/XDF/Legacy Field, imaging M87's supermassive black hole with the Event Horizon Telescope, and the "Steps to the Hubble Constant" section (added surface brightness fluctuation).
  12. In chapter 16: Added paragraph in how to measure curvature of universe. Added paragraph about recombination of helium atoms in early universe. Added section about baryon acoustic oscillations. Updates about observations of first galaxies, Hubble Constant from DES and eBOSS, dark energy, and tension with Hubble Constant measurements. Revised formatting in Cosmic Microwave Background Radiation interpretatio section and Embellishments on the Big Bang (Inflation) section to make them easier to read.
  13. In chapter 17: Updates about exoplanet discoveries (including Proxima Centauri b and d and candidate one for Alpha Cen A), habitable zones, and fixed broken links to external websites. Added paragraph with terrestrial analogy for SETI. Revised formatting in Suitable Stars section to make it easier to read.
  14. In Tables Appendix C: Updated Pluto atmosphere composition. Added table of selected large moon properties.
  15. More margin notes to aid in quickly finding particular material and noting key points.

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