Is the angular size of the black hole in the movie "interstellar" completely overblown? I assume everybody is tired of reading questions derived from the movie Interstellar, I will try to keep this short and simple:
In general in movies, in order to have stunning visuals, celestial objects are displayed as if they were extremely close to the observers, having a enormous apparent angular size.
One striking example of this that has seems counter-intuitive, is the angular size displayed for the black hole &quot;Gargantua&quot; in the movie Interstellar. The characters in the movie are so close to it that it can be fully displayed in great detail (see attached image: Black hole seems to cover almost/over 90 degrees of the field of view..!)
Now, we can fully experience gravitational pulls from much smaller objects than a supermassive black hole in reality. The angular size of the sun and the moon are so small that we need telescopes to appreciate details, despite their gravitational effects dominating our everyday life.
It seems to me that a supermassive black hole would have such immense gravitational effects, that in order to be able to &quot;freely&quot; navigate around it (as done in the movie), observers would be so far away that the angular size of the black hole would be tiny (which would result in very non-spectacular cinematography).
The question is: Realistically, for a supermassive black hole (&quot;with a mass of 100 million times of the sun&quot;), what would be roughly its angular size when standing at a &quot;safe&quot; distance from it?
Assuming the spin parameter of the black hole is close to the critical value, it could be quite large.
The scenario of heating a planet orbiting close to a black hole via blue-shifted cosmic background radiation has been explored. The shadow of the black hole would take up a large fraction of the sky on such a planet, see for example figure 1 in Bakala et al. (2020). They find that for an Earth-like planet, the region where this can be achieved is located beyond the Roche limit (where the planet would be broken up) for black hole masses $M_{\rm BH} &gt; 1.63\times10^8 M_\odot$. As shown in figure 6 of the paper, the bulk of this radiation will be in the ultraviolet, but there's probably enough visible light in the mix to make a bluish patch near the edge of the black hole shadow. Bear in mind that this would need to be a very isolated black hole, because stars would also be blue-shifted and therefore be extremely bright sources of high-energy radiation, which would be an extremely unpleasant environment.
The scenario in the movie includes an accretion disc, this scenario is considered in Schnittman (2019), who notes that for accretion rates low enough to produce the Sun-like colour of the radiation depicted in the movie, you'd have to be a long way out:

Regardless of the specific details—whether the planet is tidally locked or not, embedded
in the disk or not—it is clear that for any planet to be habitable while also receiving its
primary heating flux from a Novikov-Thorne type accretion disk, the planet either has to
be extremely far from the black hole, or the mass accretion rate has to be an infinitesimal
fraction of Eddington. This leads to an important inconsistency: The Novikov-Thorne model
is predicated on an optically thick, radiatively efficient disk. At accretion rates down near
$10^{-12} \dot{M}_{\rm Edd}$ the optical depth is unlikely to be large enough to allow the gas to cool, thus
leading to a very hot, low-density accretion flow.