Astronomy

Our Universe appears to be expanding and cooling, having originated some 13.8 billion years ago in a hot Big Bang. However, it's plausible that what we see from inside our Universe is simply the result of being inside a black hole that formed from some parent Universe. If the black holes that form in our cosmos give birth to baby Universes, perhaps we arose from the formation of a black hole ourselves.

If you said "with the Big Bang," congratulations: that was our best answer as of ~1979. Here's what we've learned in all the time since.

cross-posted from: https://lemmy.sdf.org/post/6593278

On July 19, 1952, Palomar Observatory was undertaking a photographic survey of the night sky. Part of the project was to take multiple images of the same region of sky, to help identify things such as asteroids. At around 8:52 that evening a photographic plate captured the light of three stars clustered together. At a magnitude of 15, they were reasonably bright in the image. At 9:45 pm the same region of sky was captured again, but this time the three stars were nowhere to be seen. In less than an hour they had completely vanished.

More than 70 years ago, astronomers were doing a sky survey when three bright stars they just saw disappeared, never to be seen again.

NASA has hit a significant problem. Two fasteners are stuck.

APOD October 22, 2023: Ghost Aurora over Canada

What does this aurora look like to you? While braving the cold to watch the skies above northern Canada early one morning in 2013, a most unusual aurora appeared. The aurora definitely appeared to be shaped like something, but what? Two ghostly possibilities recorded by the astrophotographer were "witch" and "goddess of dawn", but please feel free to suggest your own Halloween-enhanced impressions. Regardless of fantastical pareidolic interpretations, the pictured aurora had a typical green color and was surely caused by the scientifically commonplace action of high-energy particles from space interacting with oxygen in Earth's upper atmosphere. In the image foreground, at the bottom, is a frozen Alexandra Falls, while evergreen trees cross the middle.