--- title: How stars live — a lesson of Mova's school · trees and pragmatics description: «How stars live», a lesson of the space course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Stars are born inside huge, cold clouds of gas and dust called nebulae: a clump collapses under its own gravity, heats up and glows as a protostar hidden in --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Space](https://md.mova.elamur.ai/free/en/corpora/school/space/) / How stars live # How stars live Lesson 18 of the space course of Mova's primary school: 16 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/space/18-how-stars-live/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/0/) — Stars are born inside huge, cold clouds of gas and dust called nebulae: a clump collapses under its own gravity, heats up and glows as a protostar hidden in dust, until fusion switches on in its core. - [1](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/1/) — For most of its life a star is a tug of war held in balance: gravity pulls everything inwards, and the pressure of hot gas pushes outwards, like a balloon whose rubber squeezes in while the air pushes out. - [2](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/2/) — Stars spend about 90% of their lives steadily turning hydrogen into helium; the Sun is about 4.6 billion years old, roughly halfway through its life of about 10 billion years. - [3](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/3/) — Big stars live fast and die young, like a huge bonfire that burns out quickly, while tiny red dwarfs sip their fuel so slowly they can last trillions of years. - [4](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/4/) — Stars also build heavier elements, so most of the carbon and oxygen in your body was made inside stars that lived and died before the Sun was born. - [5](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/5/) — Stars are born inside huge cold clouds of gas and dust called nebulae, where clumps collapse under their own gravity. - [6](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/6/) — Before fusion starts, a young star is a protostar, glowing from the heat of its own collapse and hidden in dust. - [7](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/7/) — The Pillars of Creation in the Eagle Nebula are towering columns of gas and dust, each several light years tall, where new stars are forming. - [8](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/8/) — During most of its life a star is held in balance: gravity pulls inwards and the pressure of hot gas pushes outwards. - [9](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/9/) — Stars spend about 90% of their lives steadily fusing hydrogen into helium, a stage astronomers call the main sequence. - [10](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/10/) — The Sun is about 4.6 billion years old, roughly halfway through its life of about 10 billion years as a normal star. - [11](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/11/) — A star's mass decides how long it lives: a star 10 times heavier than the Sun lasts only about 20 to 30 million years, while small red dwarfs can last trillions of years. - [12](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/12/) — No red dwarf in the universe has yet died of old age, because the universe, about 13.8 billion years old, is far younger than their lifespans. - [13](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/13/) — The Sun is slowly getting brighter, by about 10% every billion years. - [14](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/14/) — Stars build heavier elements from lighter ones, so most of the carbon and oxygen in your body was made inside stars that lived before the Sun. - [15](https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/15/) — Stars born from the same cloud often stay together for a while as a cluster, like the Pleiades, about 440 light years away and about 100 million years old. - ← previous: [Stars: what they are](https://md.mova.elamur.ai/free/en/corpora/school/space/17-stars-what-they-are/) - next →: [How stars die](https://md.mova.elamur.ai/free/en/corpora/school/space/19-how-stars-die/) - ↑ back to [Space](https://md.mova.elamur.ai/free/en/corpora/school/space/)