This means it’s an asteroid with a weight-class that would have burned up in Earth’s atmosphere, if its orbit happened to intersect ours more directly.
BTW, thanks! This comment sent me down a fascinating rabbit hole. It had simply never occurred to me that energy conversation didn’t apply in an expanding universe!
The thing about photons is that they redshift, losing energy as space expands. If we keep track of a certain fixed number of photons, the number stays constant while the energy per photon decreases, so the total energy decreases.
It’s probably not that the light is losing energy it’s just that the distance it travels over time (the time we “know” is supposed to take for a given distance) appears compressed because of unknown/unseen gravitational forces.
This doesn’t seem to be at all what tired light proposes though. What you’re explaining sounds like red-shift due to an expanding universe. From what I can tell they claim it actually loses energy through interaction with “other things” in the universe.
Or the effect we see on gravitational lensing that is accounted for by “dark matter”? I don’t see how that could be explained by “light losing energy”…