MERCURY
Mercury, the closest planet to the Sun, is the second smallest planet in the Solar System. Because it is so near the Sun, it can be seen from Earth only with difficulty – low in the dawn or twilight sky close to the Sun.
Mercury’s surface looks quite similar to that of our Moon. Bare and rocky, it is covered with craters, the result of continual bombardment by meteorites during the first billion years of its existence. Originally molten, Mercury’s surface shrank as it cooled after the bombardment eased, resulting in “wrinkles” – long mountain chains. With no winds or water to erode the rocks, Mercury’s landscape has remained the same ever since.
Mercury’s orbit has an unusual shape All the other planets, except Pluto, have nearly circular orbits, but Mercury’s is elliptical – more like an oval. At its closest, Mercury is 46 million kilometres from the Sun, 70 million kilometres away at its most distant.
Mercury has great extremes of temperature. Where it faces the Sun, it can exceed 400°C, but during the long nights (lasting about 59 Earth days) and with no atmosphere to keep the heat in, temperatures can plummet to – 170°C.
Mercury’s surface is made up of thousands of craters, as well as mountains and lava plains.
Mercury, the densest planet apart from Earth, has a large metal core made of iron and nickel, surrounded by a thin rocky shell.
The landscape of Mercury is dominated by thousands of craters. The huge Sun burns with a fierce heat – turning to severe cold when this face of the planet is turned away from it. Large boulders falling from space have produced craters in Mercury’s surface measuring many kilometres across, some with smaller craters inside. Because there is hardly any atmosphere, Mercury’s skies remain black even during the day.
When a meteorite strikes the surface of Mercury, it punches a saucer-shaped crater in the ground. Debris is blasted out in all directions, creating long streaks.
Picture Credit : Google