Ephemera don't stick around for very long. You might enjoy such ephemera as sunsets and rainbows, things appearing only briefly, and so enjoyed all the more.
In Latin, ephemera was a word for a fever that didn't last long. Today, ephemera is the plural form of ephemeron, which means "something impermanent or lasting only a short time." French historian Fernand Braudel referred to events as “the ephemera of history,” likening them to fireflies that light the dark for just a moment.