CAPF AC 2022 Q94: Science & Technology – Space Technology & Astronomy
- (a) a supermassive black hole in our Milky Way Galaxy
- (b) two giant black holes spiralling around each other several light-years away from the Earth
- (c) a Supernova explosion seen in real time for the first time ever by scientists
- (d) a huge asteroid that passed by very close to the Earth
Answer: (a) a supermassive black hole in our Milky Way Galaxy
Explanation
Sagittarius A*
How to think: Sagittarius A* (read as A-star) is the supermassive black hole at the centre of our own galaxy, the Milky Way.
It was in the news in May 2022 when its first image was released.
| Fact | Detail |
|---|---|
| What it is | A supermassive black hole |
| Where | Centre of the Milky Way, in the direction of the constellation Sagittarius |
| Distance | About 27,000 light years from the Earth |
| Mass | About 4 million times the mass of the Sun |
| First image | 12 May 2022, by the Event Horizon Telescope (EHT) |
Earlier milestone: in 2019 the same telescope network gave the first-ever image of a black hole, M87*, in another galaxy.
Nobel link: the 2020 Physics Nobel went to Roger Penrose, Reinhard Genzel and Andrea Ghez for work on black holes, including this one.
Answer: (a).
Why each option is right or wrong
- (a) CORRECT. Sagittarius A* is the supermassive black hole at the centre of the Milky Way.
- (b) Incorrect. It is a single black hole, not a pair spiralling together.
- (c) Incorrect. It is not a supernova explosion.
- (d) Incorrect. It is not an asteroid; it lies 27,000 light years away.
Key point
Sagittarius A*: supermassive black hole at the Milky Way's centre, about 4 million solar masses, 27,000 light years away; first image May 2022 by the Event Horizon Telescope. M87*: first black hole image, 2019. Nobel Physics 2020: Penrose, Genzel, Ghez.
Remember
Sagittarius A* = black hole at the Milky Way's centre.
Common mistakes
- Mixing up Sagittarius A* (our galaxy) with M87* (another galaxy).
- Thinking the star mark means it is a star; it marks a compact radio source.
- Confusing it with gravitational-wave news about merging black holes.
Exam tip
Educated guess: the 2022 headline was the first picture of the black hole at the heart of our galaxy. The name of a constellation shows it is a fixed, far-off object, not a passing asteroid.
Sources
- Event Horizon Telescope Collaboration — Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022)
- The Nobel Prize in Physics 2020 — press release (Penrose, Genzel and Ghez)