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 .
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 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 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 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 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 Stars are born inside huge cold clouds of gas and dust called nebulae, where clumps collapse under their own gravity. 6 Before fusion starts, a young star is a protostar, glowing from the heat of its own collapse and hidden in dust. 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 During most of its life a star is held in balance: gravity pulls inwards and the pressure of hot gas pushes outwards. 9 Stars spend about 90% of their lives steadily fusing hydrogen into helium, a stage astronomers call the main sequence. 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 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 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 The Sun is slowly getting brighter, by about 10% every billion years. 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 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 arenext → How stars die↑ back to Space This page in Markdown → https://md.mova.elamur.ai/free/en/corpora/school/space/18-how-stars-live/