Why is early speculative fiction so grim? One reason is that early SF authors thought the sun was on the brink of death.
https://www.typebarmagazine.com/2024/03/24/science-fiction-and-the-death-of-the-sun/
@estherschindler: The rapid pace of scientific discovery back in the late 1800 and the early 20th century was terrifying to a lot of people, including many scientists. Remember, the US nuke scientists weren't sure the first atomic detonations wouldn't ignite the global atmosphere. Early telescopes and photography couldn't get Mars too clearly, and so they saw canals and huge roadways, which meant life. Oh, and plate tectonics, and let's not forget the proving that Meteor Crater was a crater.
@estherschindler: Many felt dreadfully uncertain about the Earth's and Humanity's place in this new and uncertain universe. Existential dread was real.