November 30, 2012

If Earth were a Black Hole

A contributor to the Utah Astronomy list serve recently linked its members to an article describing a galaxy whose central super-massive black hole makes up the majority (59%) of the galaxy's mass...and just so you know...that's a lot! You can read the original article here for more details.

In closing, the author asks, "What would you see if you lived on a habitable planet in that far-away galaxy and could look toward the center? Probably nothing that makes sense to human eyes. Black holes have such powerful gravity that they distort the space around them."

Coincidentally, just yesterday, Rob presented an image to his computational modeling class that relates to the above question. It simulates what the Earth would look like to an outside observer if it were 99.99% the density of a black hole...

The first thing that probably grabs your attention is a weird white ring encircling the central continents. Believe it or not, that ring is actually our seventh continent: Antarctica! And if you look closely, you might also notice that the image is so bent and stretched that you can see the Antarctic Peninsula (the arm that stretches up toward South America), twice...and from both directions. If there were a little person waving to us from the tip of that peninsula, we'd see him twice too: his smiling face at the lower left of the image, and the back of his head on the upper right.

By now you've undoubtedly noticed that parts of the other continents show up on the horizons beyond the Antarctic ring: Madagascar and southern Africa up top, Australia on the lower left, New Zealand stretched thin at the bottom, and South America encroaching on the upper right. Amazingly, if we were to increase the density of this Earth even more, the continents would come completely into view outside Antarctica, then Antarctica would appear again...and so on.

One problem is that as this happened, the light would also being severely red shifted. It would eventually reach into infrared  (beyond our visible range), and finally--as we approach an infinite density and our Earth collapses into a black hole--no light would escape at all. Our black-hole Earth would disappear...and we would be wise turn our spaceship around and make towards the next star system as quickly as possible!

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