A distant secret holds a dark secret in the form of a supermassive black hole – one of the biggest ever discovered, with mass that is 21 billion times that of our sun.

NGC 4889 has a placid outer appearance, but the Hubble Space Telescope of NASA and the European Space Agency imaged a record-breaking sight in this distant elliptical galaxy located around 300 million light years away in the Coma Cluster.

The black hole features an event horizon, where even light cannot seep out, with a diameter of around 130 billion kilometers. Such diameter is close to 15 times the diameter of Neptune’s orbit from the sun.

In contrast, Milky Way – the black hole in our own galaxy – is estimated to have a mass four million times that of the sun and an event horizon just one-fifth Mercury’s orbit.

Experts believe, however, that the black hole of this massive faraway galaxy is already past its star-swallowing and matter-devouring phase. In fact, the galaxy is now in such calm state that stars have begun forming and orbiting peacefully in the surrounding area.

Astronomers, however, would probably have categorized NGC 4889 as a quasar, a potent dynamo that shines brightly and it eclipses the ancient galaxies containing it.

“[T]he disc around the supermassive black hole would have emitted up to a thousand times the energy output of the Milky Way,” says NASA.

The supermassive black hole is now dormant, yet it allows scientists to further study where and quasi-stellar radio sources or quasars, a fascinating discovery from half a century ago, formed in the universe’s early days and beginnings.

Astronomers used instruments aboard the Keck II Observatory as well as the Gemini North Telescope to indirectly observe the black hole’s mass. They measured the velocity of stars loitering around the galaxy’s center, which will reveal the overwhelming mass of the humungous subject at hand.

On the other hand, a new international project is on a mission to investigate the cosmos. Astro-H X-ray Observatory, a collaborative program among different space agencies including NASA and ESA, seeks to find new data on highly energetic processes in the universe, such as black holes, supernovae, and cluster formations in galaxies.

Touting Astro-H as the “next big X-ray observatory,” the international team will arm the satellite with highly specialized X-ray telescopes and detectors for a higher-resolution look at space than current telescopes can afford.