In 2009, a team of astronomers used the Swift Spacecraft to measure the luminosity output of a distant Quasar, named S5 0014+81, and  measure the mass of the central black hole. To their surprise, they found out that this black hole contains actually 40 billion solar masses, that is 10,000 times more massive than the black hole at the center of our galaxy. This makes it one of the most massive black holes ever discovered, more than six times the value of the black hole of Messier 87, which was thought to be the largest black hole for almost 60 years, and was coined to be an “ultramassive” black hole. The Schwarzschild radius of this black hole is 118 billion kilometers. In the picture above the event horizon of this ultramassive black hole is compared to oursolar system (i.imgur.com).

Black holes can actually lose mass. Stephen Hawking theorized in 1974 that black holes radiate small numbers of particles (mainly photons), a process known as “Hawking Radiation”. This “evaporation” process can lead the black hole to shrink over time and ultimately to vanish completely. However, it is a staggeringly slow process: it would take about 10^67 years for a black hole the mass of the Sun to evaporate, significantly longer than the 14 billion years the Universe has existed.