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Lesson
Neutron stars — a thimble heavier than a mountain
Understand what remains after a massive star explodes and how monstrously dense matter can be.
A city-sized star
What a neutron star is
When a massive star explodes as a supernova, its core can collapse into a neutron star — one of the strangest objects in the universe.
Imagine: more mass than our Sun squeezed into a ball only about 20 kilometers across — the size of a city. The matter is packed so tightly that a single teaspoon of this “star” matter would weigh about as much as a whole mountain — hundreds of millions of tons.
Neutron stars spin furiously — sometimes hundreds of times a second. Some of them shine in narrow beams, like a cosmic lighthouse: the beam sweeps across Earth at precise intervals, and we pick up steady “tick-tock” pulses. Such stars are called pulsars.
When the first pulsar was discovered in 1967, the signal was so regular that it was jokingly labeled LGM-1 — “little green men.” But it turned out to be nature, not aliens.
Lesson notes
What a neutron star is
When a massive star explodes as a supernova, its core can collapse into a neutron star — one of the strangest objects in the universe.
Imagine: more mass than our Sun squeezed into a ball only about 20 kilometers across — the size of a city. The matter is packed so tightly that a single teaspoon of this “star” matter would weigh about as much as a whole mountain — hundreds of millions of tons.
Neutron stars spin furiously — sometimes hundreds of times a second. Some of them shine in narrow beams, like a cosmic lighthouse: the beam sweeps across Earth at precise intervals, and we pick up steady “tick-tock” pulses. Such stars are called pulsars.
When the first pulsar was discovered in 1967, the signal was so regular that it was jokingly labeled LGM-1 — “little green men.” But it turned out to be nature, not aliens.