Evaluation:
Published: 23.01.2020.
Language: English
Level: Secondary school
Literature: 3 units
References: Not used
  • Presentations 'Black Holes', 1.
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Extract

The meeting of two black holes
Very powerful gravity results in attraction;
They get closer and closer, spinning around one another;
The collective mass shakes the fabric of nearby space-time;
Gravitational waves – proof of black holes, observed via LIGO* (2015);

How do we know black holes exist?
It cannot be seen because of the strong gravity – light is pulled into its center;
The effects can be seen on nearby stars and gases;
The motion of the star can be studied to determine whether it’s orbiting a black hole;
The gravity can be so strong it pulls off the outer gases of a star and grow a disk around itself called the accretion disk:
Gas from the disk spirals into the black hole
Heats up to very high temperatures
Result: X-ray light in all directions which is measured by NASA telescopes;
Useful to learn more about the properties of a black hole.

Author's comment
Atlants