Mercury Lesson 3 of the space course of Mova's primary school: 17 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 Mercury is the smallest planet and the closest to the Sun, a grey, cratered ball only a little bigger than our Moon. 1 It races round the Sun in just 88 days, which is why it is named after the fast Roman messenger god. 2 But it spins so slowly that one sunrise to the next takes 176 days, so on Mercury you could have two birthdays between one sunrise and the next. 3 Mercury has almost no air to hold heat, like a desert night but far worse: the day side is hot enough to melt lead and the night side colder than Antarctica. 4 Even so, it is not the hottest planet, and in deep shady craters near its poles there is ice, like snow that lasts all spring in a corner the sun never reaches. 5 Mercury is the smallest planet and the closest to the Sun, only a little bigger than our Moon. 6 Jupiter's moon Ganymede and Saturn's moon Titan are both wider than Mercury, though Mercury is heavier than either. 7 Mercury goes round the Sun in just 88 Earth days, faster than any other planet. 8 Mercury spins very slowly, so one sunrise to the next takes about 176 Earth days, two of its years. 9 Mercury's daytime surface reaches about 430 degrees Celsius, hot enough to melt lead, but at night it falls to about minus 180, because it has almost no atmosphere to keep heat in. 10 Although Mercury is closest to the Sun, it is not the hottest planet; Venus is, because its thick air traps heat. 12 Mercury's surface is covered in craters like the Moon's, and the Caloris Basin is about 1,500 kilometres across. 13 There is water ice hidden in permanently shadowed craters near Mercury's poles. 15 Mercury has no air, rain or moving plates of crust to wear its craters away, so they last for billions of years. 16 A spacecraft falling towards the Sun speeds up, so to stay in orbit round Mercury it must brake hard; it slows itself by flying past planets on the way. 17 Only three spacecraft have gone to Mercury: Mariner 10 in the 1970s, MESSENGER, which orbited from 2011 to 2015, and the European-Japanese BepiColombo, due to enter orbit in late 2026. 18 Mercury is hard to spot because it never strays far from the Sun, so it is seen only low in the sky just after sunset or before sunrise. ← previous How the Solar System was bornnext → Venus↑ back to Space This page in Markdown → https://md.mova.elamur.ai/free/en/corpora/school/space/3-mercury/