Listen&Learn: Quasars

Learn about the bright centres of young galaxies.

Pre-listening vocabulary

• celestial: relating to space
• emit: to give off energy
• abbreviation: a shortened word
• radio: a form of invisible waves of energy
• nucleus: the centre of something
• light year: the distance that light can travel in a year, about 9.46 trillion km

Listening activity

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Gapfill exercise

A quasar is a celestial object that emits enough radiation to glow brighter than a . The energy that a quasar emits comes from a supermassive black hole at its . When scientists first observed quasars in 1961, they thought they were , or star-like objects. The name “quasar” is an abbreviation for “quasi-stellar radio source”, because the first observed quasars looked like stars that emitted lots of radio waves. Scientists now know that quasars are the nuclei of galaxies. Even though quasars are very bright, most of them are billions of light years away, which means that observing them can provide information about the state of the universe in the distant . The oldest discovered quasar formed nearly 13 billion years ago, at the very beginning of the universe’s life.

Comprehension questions

See answers below

1. A quasar is
   a. a massive and luminous galaxy
   b. a star that emits an unusual amount of radio waves
   c. a bright galactic nucleus powered by a black hole
   
2. Scientists first discovered quasars in
   a. 1913
   b. 1931
   c. 1961
   
3. Most quasars are
   a. billions of light years away
   b. close to the Milky Way Galaxy
   c. almost as old as the universe

Discussion/essay questions

1. What do you think the purpose of studying space is? Why do humans want to understand the universe?

Transcript

A quasar is a celestial object that emits enough radiation to glow brighter than a galaxy. The energy that a quasar emits comes from a supermassive black hole at its centre. When scientists first observed quasars in 1961, they thought they were stars, or star-like objects. The name “quasar” is an abbreviation for “quasi-stellar radio source”, because the first observed quasars looked like stars that emitted lots of radio waves. Scientists now know that quasars are the nuclei of young galaxies. Even though quasars are very bright, most of them are billions of light years away, which means that observing them can provide information about the state of the universe in the distant past. The oldest discovered quasar formed nearly 13 billion years ago, at the very beginning of the universe’s life.

Answers to comprehension questions

1c 2c 3a