Mercury has the most craters of any planet in the solar system. Mercury's atmosphere is so thin that it provides no protection against meteor strikes. Mercury's surface has been littered by crater impacts, giving it the appearance of our Moon. The last major impact on Mercury was over 4000 years ago.
Most of Mercury is covered by a thick crust of rock that extends for hundreds of miles. But deep beneath this crust are massive reservoirs of molten iron. Because of these reservoirs, some scientists believe that Mercury may be able to restore itself after future asteroid strikes.
The Earth also has many craters from past collisions and asteroid strikes. However, over time the surface is resurfaced by erosional processes such as wind and water. This means that the number of craters on Earth is decreasing because they are filling in with new soil.
When astronomers look at Mercury through a telescope, they often see features called "dark spots." These dark spots are actually regions where the metal underneath the surface has been exposed by erosion. The black color comes from carbon-dioxide gas that has been trapped under the surface.
The Sun causes problems for planets like ours by heating them up, causing their surfaces to melt. For Mercury, this heat source is too powerful and leads to volcanic activity on its surface.
Mercury's surface is similar to that of Earth's moon, with many impact craters caused by impacts with meteoroids and comets. The most prominent feature on Mercury's surface is Marius Hills, a group of about 40 volcanic mountains that rise more than 3 miles (5 km) above the planet's surface.
Like Earth, Mercury has a thin atmosphere made up of gases such as oxygen, carbon dioxide, and nitrogen. However, because Mercury is so much closer to the Sun than Earth, its atmosphere gets heated up and evaporated. The remaining gas molecules then scatter over the planet's surface.
The best known object in Mercury's orbit is Mercury itself. Because it is so small, we can see it from Earth almost exactly as far as the Moon can be seen from Earth (about 37,000 miles/60,000 km).
However, because Mercury orbits so close to the Sun, only 0.35 AU away (or 29 million miles/46 million km), it experiences very high temperatures. In fact, the temperature at Mercury's orbit is 450°F (232°C). Because it is so hot, there is no water or other liquid on Mercury's surface, just rocks and minerals that have been melted by the heat of the sun over time.
It has several impact craters. Mercury is virtually completely devoid of atmosphere. Mercury's dark side is that it is extremely cold since it has practically no atmosphere to hold in heat and keep the surface warm.
The Earth's moon has been very important in shaping human history. But despite being only one-sixth as big as Earth, Mercury has always been a difficult planet to reach. Because it is so close to the sun, Mercury has an extremely eccentric orbit, which takes it anywhere from 87 million to 413 million miles from the Sun. This makes it an extremely hot planet with volcanoes and other features we might want to preserve when exploring it from space.
As you might expect, most of Mercury is made up of hard volcanic rocks formed as lava flows on the edge of large plates of crust that slowly break away from the planet's core. There are two large regions where these plates converge and collide, forming huge mountains: The Mariner Range in the west and the Caloris Basin in the east. These collisions also cause great amounts of heat to be released, which results in large areas of smooth plains called maria (which means "seas" in Latin) that cover much of Mercury. The largest known mare is Serenitatis, which covers more than 1,000 km 2.
Craters may be found on all terrestrial planets, including Mercury, Venus, Earth, and Mars. Craters can also be found on the surfaces of asteroids and the rocky, ice-covered moons of the outer gas planets. The Moon's surface is completely covered by numerous small impacts craters.
The Earth has been through a lot over its 4.5 billion year history. Most of the time it has had a constant temperature, but about 5% of that time has been spent in ice ages where most of North America was covered by ice sheets. There has been another hot period called the Holocene when we live in now. Both of these states caused major changes to our planet which led to the creation of many new features: mountains, valleys, etc. These changes are what cause damage to vehicles on area road trips - erosion on the sides of the roads - and they also provide some opportunities for life to find new places to live.
When objects crash into each other at high speeds, many things can happen. Sometimes they might even merge into one big object like when two rocks collide or when a meteorite hits Earth. More often than not, the impact melts something on their target body (like rock) and makes it flow like liquid down a hillside or vaporize part of its surface. This "deforms" the object into a crater.
Mercury, along with Venus, Earth, and Mars, is a rocky planet. It, like our Moon, has a solid surface covered with craters. It has no moons and has a scant atmosphere. Mercury prefers to keep things as simple as possible. There are two large regions: a tropical zone where water may be present in the form of lakes or seas, and a cold desert where nothing can live.
The landscape of Mercury is dominated by lava flows from ancient volcanoes. The largest volcano is Marius Hills, which reaches a height of 4,350 feet (1,362 meters). It is made up of andesitic lava. There are many smaller volcanoes too, some of which still spew out lava periodically. Some of the more notable ones are Ina Yusonoff Valley, Kasei Vallis, and Caloris Basin.
Lava generally does not contain much water, so most of the places on Mercury's surface have been completely destroyed by erosion. The only exceptions are several large basins filled with rock debris that was once part of the crust but now lies beneath the surface.
There are three major geologic periods on Mercury: the Hadean, the Merensky Ocean period, and the Chaotic Era.
The Hadean era lasted from 4 billion years ago to about 3 billion years ago.
It has a solid surface covered in craters. It does not have an atmosphere and no moons. The name Mercury comes from the Greek word for silver because of its color.
How many planets are in the Solar System? There are eight known planets including Pluto which was considered a planet until 2015. Even after that announcement, other bodies such as trans-Neptunian objects (TNOs) have been found through indirect methods. Therefore the number of planets in the Solar System may be as high as 9 or as low as 7. Of the nine planets, 3 are large enough for water to exist in a liquid state under their own gravity - Jupiter, Saturn, and Uranus. The other 6 are small enough that they cannot support a gravitational field strong enough to keep water liquid on their surfaces.
Of the 8 planets, 4 have atmospheres made up of gas molecules. These molecules are visible to astronomers using tools called telescopes. Information about what's going on within these gases can be learned by studying how they move across the face of the planets or rotate around their axes.
Out of the four gaseous planets, only Neptune has a dense cloud cover that hides most of the surface from view.