Without a warning, Earth was enveloped by a beam of intense light from the center of the galaxy. The pole of the supermassive black hole Sagittarius A* was pointing at our planet. It was the end of human civilization.
People who were outdoors were evaporated immediately, and only a faint shadow of their existence was imprinted on the ground where they stood. Much more horrifying fates awaited people inside the buildings. The hot air evaporated the glass in the windows and entered their rooms. Their skin, exposed to extremely high temperatures, melted to flesh as they experienced enormous pain for a fraction of a second. Fortunately, it didn’t last long; they died quickly. Or maybe not….
We have recently discovered that the axis of rotation of Sagittarius A*, the supermassive black hole at the center of the Milky Way, is oriented in such a way that we are facing its pole. This is surprising because the planes of the spiral disks of galaxies would tend to align with the equatorial regions of the event horizons of supermassive black holes at their centers.
When these monsters become active by feeding on vast amounts of matter, they can evolve into active galactic nuclei or quasars. A beam of intense radiation can then emerge from their poles that can seriously damage everything in its way. We recently observed one causing nova explosions in the giant elliptical galaxy M87.
Nevertheless, the supermassive black hole at the center of our galaxy is 4.3 million times the mass of the Sun and is relatively modest in size compared to the mass of our galaxy and other supermassive black holes elsewhere. We are located 26,000 light-years away from the center, and a significant amount of gas and dust along the way would block some of the radiation. The above scenario could happen in other galaxies, which contain supermassive black holes hundreds of times or more massive than the one we have in the Milky Way.
At most, the Earth’s atmosphere would get seriously damaged, and dark clouds would appear that would block the energy of the sun for years, causing nuclear war-like conditions and famine that could dent the human population to a large extent.
We think that our supermassive black hole has been in its active galactic nucleus phase or quasar many times in the past. In other galaxies, they last millions to even up to a billion years, but their length depends on the sources of matter the supermassive black hole can feed on. It can be from a recent galactic merger. Our galaxy has not collided with a huge one for 8 to 11 billion years since the Gaia-Encaladus-Sausage galaxy increased the number of stars in the Milky Way by about 50 billion.
Perhaps the next quasar phase will occur after the merger with the Andromeda Galaxy and its supermassive black hole, which is 20 to 30 times more massive than our own. This might be in 4.5 billion years or more. This behemoth of a unison between two supermassive black holes could do far more damage, and its galaxy would supply theirs, stir up and move our nebulae that can feed this voracious source of destruction for hundreds of millions or even a billion years.
The question was: How would earth be affected if the super massive black hole at the center of the galaxy turned into a quasar?