The Universe Around US

A popular-science astronomy book written in the early 20th century. It presents a clear, nontechnical survey of observational and theoretical astronomy—from the solar system and stars to nebulae, galaxies, cosmogony, and the large-scale structure of the cosmos—framed by the question of humanity’s place in the universe and updated with then-new findings such as Pluto, galactic rotation, and cosmic expansion. The opening of this work recounts how Galileo’s telescope overturned the geocentric worldview (with the moons of Jupiter and the phases of Venus), traces the cultural resistance and eventual shift in human self-understanding, and explains why astronomy matters—existentially, scientifically, and aesthetically. It sets a vast time-scale perspective (Earth’s age versus the brief span of human and scientific history) and proposes that current astronomy offers only first approximations, like pieces of a jigsaw. Beginning its survey, it outlines the solar system (inner rocky planets, asteroid belt, giant outer planets, and newly found Pluto), questions Bode’s “law,” and sketches planetary conditions and temperatures. It then describes Herschel’s star counts and the biscuit-shaped galactic system, distinguishes planetary, galactic, and extra-galactic (spiral) nebulae, and emphasizes the colossal scale of systems like Andromeda. The text explains how stellar distances were first measured via parallax and builds the “distance ladder” from Earth to light-years, noting photography’s transformative role. It introduces star groups and binaries, uses Newton’s gravitation to show how stellar masses are weighed (and how luminosity varies dramatically with mass), and summarizes spectroscopic and eclipsing binaries. Finally, it introduces variable stars—especially Cepheids—pointing toward the period–luminosity relation that makes them cosmic distance markers.