Planets could orbit singularities inside black holes

Certain black holes can have a complex internal structure that could allow photons, particles, and perhaps even planets to orbit the central singularity without ever getting sucked all the way in, Technology Review Physics arXiv Blog reports.
“Advanced civilizations may live safely inside the supermassive black holes in the galactic nuclei without being visible from the outside,” says Vyacheslav Dokuchaev, Institute for Nuclear Research of the Russian Academy of Sciences in Moscow.
Of course, such a civilization would have to cope with extraordinary conditions, such as huge tidal forces and the huge energy density that builds up in these stable orbits as photons become trapped.