Pummelled and scarred from billions of years of relentless and violent space impacts. The Moon is our constant companion in space, Earth’s only natural satellite at 4.5 billion years old, 238,897 miles away, and the same age as the Earth. It has mountains, seas (lava flows), and is covered in craters. It’s only about 27 % of the Earth’s size, and only 60 % the density of our planet. The Moon is riddled with craters from asteroid and comet impacts, most happened early on in the formation of the solar system billions of years in the past. But the Earth has recieved just as hard a battering from space as our Moon, in fact more because of it’s larger size. But why isn’t the Earth just as cratered as the Moon? 
Actually our planet has been heavily cratered just the same as the Moon, but the Earth is a very geologically active place so most of these impact scars have been erased and do not survive for millions and billions of years, although a few do remain. This photo shows Meteor Crater in Arizona, a 2.4 mile wide, 550 foot deep impact crater from a 150 foot asteroid that hit around 50,000 years ago.
Some craters on the Moon are in permanent shadow, especially near the south pole and can be at -240 degrees C. The Moon though is a geologically dead world, and there is no atmosphere so any disturbances on the surface could stay for millions of years or more. The Nasa Apollo astronauts’ footprint tracks in the Lunar dust are just as pristine today as when they were made 40 years ago, imaged by the Nasa Lunar Reconnaissance Orbiter. No atmosphere on the Moon also means the sky is black even in the daytime, and the stars are always visible. At the equator the temperature can reach 127 degrees C, and at night can drop to -173 degrees C. When you look at the Moon through binoculars, telescope, or the naked eye can see dark and light areas. The dark areas are maria which is Latin for seas, because that’s what they looked similar to. 
These are actually ancient lava flows formed back in the time billions of years ago when there were once volcanoes on the surface. The lava flowed across the surface and froze in position. They now show up as smooth, dark regions which over time have collected meteor impact craters. This photo shows the ancient lava flow the Sea of Tranquility. These maria cover about 16 % of the Moon’s surface and have names like Mare Imbrium (Sea of Rains), and Mare Serenitatis (Sea of Serenity). The Moon’s surface also has a very varied terrain of highlands, mountain ranges, canyons, and scars. Sometimes rilles can be seen in the maria, these are long winding depressions that look like river valleys. In fact scientists used to think they were ancient river beds, they are actually old lava channels.
The Moon rotates on it’s axis once every 29.5 days, called the Lunar day. As the Moon orbits Earth different parts are in sunlight and these change night by night, these are the phases of the Moon. It has four main phases called new Moon, first quarter, full Moon, and last quarter. A new Moon is when it is directly between the Sun and the Earth and the sunlit side is facing away from us. As the Moon goes through it’s phases, the boundary between light and dark is called the terminator. Looking along the terminator in your binoculars or telescope is fantastic to see mountains, valleys, craters, and scars on the Moon as the Sun picks out details and casts shadows that would otherwise be invisible during a full Moon. It’s an ever changing scene and looks breathtaking in a large telescope where just one or two craters can be seen in one field of view. Huge amounts of details can also be viewed using binoculars.
Craters less than 6 miles in diameter have the classic bowl shape, larger craters though have higher walls to them and their steepness causes them to collapse in on themselves creating a flatter floor to the crater. Even larger craters can have central peaks and their walls a terraced appearance like steps into the crater. The central peaks you might see in your telescope are caused when the ground compresses with the impact, and then rebounds forming a point. Rocks in these central peaks may come from as far as 12 miles down in the Lunar crust. Areas around the edges of craters are mountainous and rough, strewn with the debris that was excavated by the comet or meteor. This material thrown from the crater is called the ejecta blanket, and can extend as far as 60 miles out from the impact. 
This photo from Apollo 15 shows a 4 kilometre wide crater called Linne, on the western part of Mare Serenitatis. It is quite young and the ejecta blanket can be seen surrounding the impact.
The most impressive crater rays are usually found to be the most recent because the fine powdery material eventually gets disturbed by other impacts nearby. This photo shows the famous craters Tycho at top left, and Copernicus at bottom right. These two are great examples of crater rays.Ancient people thought the Moon was a huge mirror that reflected the Earth’s sea and land, others thought is was a bowl of fire in the sky. It was also thought that the Moon was just like Earth and people lived there. It is now thought that our nearest neighbour was formed from a cataclysmic collision 4.533 billion years ago when a celestial body the size of Mars crashed into the young Earth. This impact body was called Theia, the name Theia is derived from a Greek goddess, a titan who gave birth to the Moon Goddess Selene. Theia is thought to have collided with Earth when the solar system was still being formed. Theia’s iron core and mantle fused with Earth in the titanic collision, throwing off large parts of Earth’s crust into space and ending up in orbit around our young planet. In a time that took between a month and a century, the material collected together around the Earth, to eventually form the Moon as we know it today. Rocks brought back by Apollo astronauts support this idea, as the composition is very similar to Earth and suggests that the Moon was once molten.