There is a black hole sitting roughly 10 billion light-years away from Earth, called TON 618, with a mass about 66 billion times that of our Sun — more massive than every star in the Milky Way galaxy

Key Points:

• TON 618 is a quasar located about 10.8 billion light-years from Earth, powered by one of the most massive black holes ever measured, with mass estimates ranging from approximately 40.7 to 66 billion times that of the Sun.
• This black hole's mass rivals or exceeds the total stellar mass of the Milky Way galaxy, making it "ultramassive" and far larger than typical supermassive black holes like Sagittarius A* at the Milky Way's center.
• The black hole's event horizon spans thousands of astronomical units, large enough to engulf the entire solar system multiple times over, highlighting its enormous gravitational influence.
• TON 618 was initially misidentified as a faint blue star in 1957 and only correctly classified as a quasar in the 1970s after radio and optical observations revealed its high redshift and broad emission lines.
• The mass estimates rely on indirect virial methods using emission-line widths, which carry significant uncertainties; theoretical models suggest an upper mass limit for black holes around 50 billion solar masses, placing TON 618 near or above this threshold depending on the estimate.