Q 01/05

What is the boundary around a black hole beyond which nothing can affect an outside observer called?

A) Photon sphere

B) Event horizon

C) Ergosphere

D) Singularity

Answer · why

B) Event horizon

Event horizon: to a distant watcher, anything falling toward it seems to slow and freeze at the edge, never quite crossing, as its light fades away.

Q 02/05

What is the name of the supermassive black hole at the centre of the Milky Way?

A) Cassiopeia A

B) Markarian 421

C) Sagittarius A*

D) TON 618

Answer · why

C) Sagittarius A*

Sagittarius A*: thick dust hides the galaxy's centre from ordinary telescopes, so astronomers found it in 1974 by its radio waves, which pass straight...

Q 03/05

In which year was the first-ever image of a black hole published?

A) 2011

B) 2015

C) 2017

D) 2019

Answer · why

D) 2019

The result was announced in six simultaneous press conferences around the world on 10 April.

Q 04/05

The first photograph of a black hole, released in 2019, showed the object at the heart of which galaxy?

A) Andromeda

B) Messier 87

C) Centaurus A

D) Triangulum

Answer · why

B) Messier 87

Messier 87: a century before the photo, astronomers had spotted a strange straight ray poking from its core, now known to be a jet of gas blasted out ...

Q 05/05

In which year did astronomers unveil the first image of the black hole at the centre of our own galaxy?

A) 2022

B) 2023

C) 2024

D) 2025

Answer · why

A) 2022

The image had been delayed because data from the South Pole Telescope could not be flown out until the austral winter ended.