Are any black holes known to have satellites?

 If the Sun were suddenly replaced by a black hole of identical mass, Earth wouldn't be sucked in—it would simply become a dark, frozen satellite.

Gravity works exactly the same around a black hole as it does around any other celestial object, provided you remain outside the event horizon. Because of this, anything that can orbit a star can orbit a black hole.

The most prominent examples of black hole satellites are the stars orbiting Sagittarius A*, the supermassive black hole at the center of the Milky Way. Astronomers have tracked a cluster of objects, known as the S-stars, for decades as they loop around the galactic center.

One of the most intensely studied is S2, a massive, bright blue star that completes a highly elliptical orbit every 16 years. By watching S2 and its peers trace perfect orbital paths, astronomers mapped the exact mass of the central black hole. In 2018, S2 made its closest approach, passing within 20 billion kilometers of the event horizon and reaching speeds over 25 million kilometers per hour.

An illustration of the star S2's orbit around the supermassive black hole at the center of the Milky Way. Photo by ESO/M. Kornmesser is licensed under CC BY 4.0.

On a smaller scale, stellar-mass black holes frequently have satellite companion stars. In X-ray binary systems, a star and a black hole orbit a shared center of mass. The black hole slowly strips away the companion star's outer layers, pulling the material into a swirling accretion disk. V404 Cygni is a prime example: a black hole about nine times the mass of the Sun is orbited by a small star roughly half the mass of our Sun every 6.5 days.

Even planets could theoretically orbit black holes. Astrophysical models suggest that the massive disks of dust and gas surrounding supermassive black holes could clump together into planetary bodies, much like they do in protoplanetary disks around young stars. These proposed objects, sometimes dubbed "blanets," could form tens of light-years away from the event horizon, settling into stable, long-term orbits in the dark.

Did we know the shape of the continents before satellites?

 Here’s a 1950 map of Earth, 7 years before Sputnik launched:

Here’s a 1900AD map of Earth, 57 years before Sputnik:

And a 1900 globe projection of Earth:

And an 1850 map of Earth. It’s getting a bit rougher at the north and south poles, which were barely explored at the time.

An 1852 map:

A 1798 map of the world: not much worse than 1850.

By 1750, there were some real blanks at the far edges of the world from Europe:

1700 map - not much worse than 1750, allowing for the limits of the projection.

1630 map - missing a certain land down under:

1570: definitely some room for improvement, but the cartographer’s heart (and continents) are in the right places.

1502: a few holes here and there, but it was up to date with European explorations.

Short answer: yes, we figured out the shape of continents before satellites.