#  Are there any stellar-mass black holes near the Solar System and can you detect them by using the EHT? 

 



 There are lots of stellar-mass black holes that are much closer to the Solar System than Sgr A\* in the Galactic Center. However, the size of a black hole is proportional to its mass, so these stellar-mass black holes look much smaller than the Galactic Center black hole. Even if we can *detect* some stellar-mass black holes with the EHT, we would not be able to *resolve* the emission around them on the scale of their event horizon.

 The closest currently known black hole is V616 Monocerotis, 3,000 light-years away, with a mass of 11 times larger than our Sun (Sun’s mass, or Solar mass, is approximately 333,000 times the mass of the Earth). It orbits a K-type star (0.5 Solar masses) with a period of about 8 hours, which causes its light to vary periodically. At double the distance, we have Cygnus X-1 (15 solar masses), orbiting an O-type star (30 Solar masses) with a period of around 6 days.