cosmo
Explanation
In this comic, a scientist stands at a podium delivering a dramatic summary of modern cosmology to an enthusiastically applauding audience. His announcement captures the two most existentially deflating conclusions of cosmological science in a single sentence: the universe is expanding away from us (referring to the metric expansion of space, in which distant galaxies recede from every point), and we are not special in any way (the Copernican principle, which holds that Earth occupies no privileged position in the cosmos).
The caption reads: "Cosmology is the most depressing science." The joke is that cosmology uniquely combines two demoralizing facts -- the universe is literally fleeing from us, and we don't even matter enough for that to be personal. Unlike other sciences that might deliver bad news (medicine telling you you're sick, ecology telling you the planet is dying), cosmology tells you that the entire universe is indifferent to your existence on a structural level. The audience's enthusiastic applause adds an extra layer of humor, as they are cheerfully clapping for what amounts to the most comprehensive dismissal of human significance possible.