--- title: The Earth as a planet — a lesson of Mova's school · trees and pragmatics description: «The Earth as a planet», a lesson of the space course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Our Earth is the third planet from the Sun, a rocky ball like Mercury, Venus and Mars, but the biggest of the four and the only one we know with life. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/) [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/) / The Earth as a planet # The Earth as a planet Lesson 5 of the space course of Mova's primary school: 15 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/5-the-earth-as-a-planet/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/0/) — Our Earth is the third planet from the Sun, a rocky ball like Mercury, Venus and Mars, but the biggest of the four and the only one we know with life. - [1](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/1/) — It spins once a day, which gives us day and night, and it races round the Sun once a year at about 30 kilometres every second, though we never feel it, just as you do not feel a smooth train. - [2](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/2/) — The Earth leans over by about 23.4 degrees, and this tilt, not our distance from the Sun, makes summer and winter: in summer your half leans towards the Sun. - [3](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/3/) — Inside, it is like a peach: a thin crust of rock, a thick hot mantle, and an iron core whose swirling liquid part makes a magnetic shield against the solar wind. - [4](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/4/) — Seen from Voyager 1 six billion kilometres away, the whole Earth was a pale blue dot smaller than a single pixel. - [5](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/5/) — The Earth is the third planet from the Sun and the largest of the four rocky planets. - [6](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/6/) — The Earth is the only place in the universe where we know life exists, and the only planet known to have liquid water oceans on its surface. - [7](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/7/) — The Earth's axis is tilted by about 23.4 degrees, and this tilt, not our distance from the Sun, causes the seasons. - [8](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/8/) — The Earth spins once in about 24 hours, giving day and night, and goes round the Sun in about 365.25 days. - [9](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/9/) — The extra quarter of a day each year is why we add a leap day, 29 February, about every four years. - [10](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/10/) — The Earth has a thin rocky crust, a thick hot mantle, a liquid iron outer core and a solid iron inner core. - [12](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/12/) — The Earth's air is about 78 percent nitrogen and 21 percent oxygen, and the oxygen was made by living things such as tiny ocean microbes and plants. - [13](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/13/) — The Earth is the only planet known to have plate tectonics: the crust is broken into plates that slowly move. - [14](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/14/) — The Earth bulges slightly at the equator, being about 43 kilometres wider across the equator than from pole to pole. - [15](https://md.mova.elamur.ai/free/en/corpora/school/space/5-the-earth-as-a-planet/15/) — The Earth races round the Sun at about 30 kilometres per second, about 107,000 kilometres per hour. - ← previous: [Venus](https://md.mova.elamur.ai/free/en/corpora/school/space/4-venus/) - next →: [The Moon](https://md.mova.elamur.ai/free/en/corpora/school/space/6-the-moon/) - ↑ back to [Space](https://md.mova.elamur.ai/free/en/corpora/school/space/)