Long-Term Fate: Over centuries, the solar system would gradually fall toward TON 618, eventually crossing its event horizon (which spans about 1,300 AU, or roughly 0.02 light-years). However, this process would take around 100–200 years based on Newtonian approximations for free fall from rest, and relativistic effects near the black hole would complicate things further. Spaghettification and other horrors await close to the horizon, but Earth wouldn't survive long enough for that.
The real killer would be TON 618's quasar activity. It's one of the brightest known objects, with a luminosity of 4 × 10⁴⁰ watts (equivalent to about 100 trillion times the Sun's output). At 4.37 light-years:
- Overwhelming Flux: Earth would receive approximately 1.86 million watts per square meter from TON 618—over 1,300 times the solar constant (the energy Earth gets from the Sun). This is equivalent to placing Earth at about 0.026 AU from the Sun (roughly 5–6 solar radii), where temperatures exceed thousands of degrees.
- Immediate Consequences:
- Atmospheric Destruction: High-energy radiation (UV, X-rays, and possibly gamma rays from the accretion disk and jets) would instantly ionize and strip away Earth's atmosphere, obliterating the ozone layer and exposing the surface to lethal doses.
- Surface Heating: The intense energy would cause global temperatures to spike rapidly. Oceans would boil away in minutes to hours, rocks would melt, and the surface would turn into a molten hellscape. Equilibrium blackbody temperature calculations suggest averages exceeding 1,500 K (over 1,200°C), hot enough to liquefy iron.
- Biological Extinction: Any life would be eradicated almost instantly by radiation and heat. Even underground or oceanic life couldn't survive the planet-wide sterilization.
- Broader Solar System Impact: The Sun and other planets would face similar bombardment, potentially disrupting stellar atmospheres or planetary magnetospheres, but Earth's fate would be sealed first.
In summary, while gravity might not immediately dismantle the solar system, the quasar's radiation would render Earth uninhabitable and likely destroy it as a solid body within a very short timeframe—far before any gravitational ingestion.
Tl;dr - that'd be their view for a few tenths of a second before the atmosphere got vaporized and them along with it.