Year-ender: Historical human breakthroughs in 2019

Space exploration

Cracking mystery of the black hole

The first-ever image of a black hole, a joint effort of more than 200 astronomers worldwide, including 16 from the Chinese mainland, was released on April 10. It was the first visible representation of the existence of what are considered the most extreme objects in the universe.

The image depicts the black hole at the heart of Messier 87, a massive, distant galaxy in the nearby Virgo galaxy cluster. The photo is important because it is the first time that we humans have "observed" black holes; it also provides solid evidence to support the general theory of relativity, which Albert Einstein propounded one century ago.

Furthermore, an international team of scientists led by China has discovered a king-size, stellar-mass black hole in Earth's "cosmic backyard" containing the mass of 70 suns. It is the biggest known of its kind and roughly three times bigger than what scientists previously thought was possible.

The discovery of the stellar-mass black hole challenged astronomers' understanding of the formation models for black holes of its class, and provided a new way to find similar black holes in our own Milky Way galaxy that may lead to new theories for black hole astrophysics and stellar evolution.