TON 618

TON 618 is an extremely luminous quasar in the constellation Canes Venatici. Its light travelled for about 10.4 billion years – we see it as it was when the universe was a little over 3 billion years old.

At its centre sits one of the most massive known black holes: roughly 40 to 66 billion solar masses depending on the measurement. Its event horizon would have a radius of about 1,300 astronomical units – over forty times Neptune's orbit, big enough to swallow our whole Solar System.

A quasar is the extremely bright core of a young galaxy: gas falls onto the black hole, forms a hot disc and radiates more brightly than hundreds of trillions of Suns.

In the sky TON 618 is just a single faint point (15.9 mag) and needs a large telescope. There is no photograph of the disc or the black hole itself: the pictures in the gallery are artist's impressions and do not show TON 618 itself.