What type of atmosphere does mercury have

That means it spins nearly perfectly upright and so does not experience seasons as many other planets do. Mercury formed about 4. Like its fellow terrestrial planets, Mercury has a central core, a rocky mantle, and a solid crust.

Mercury is the second densest planet, after Earth. It has a large metallic core with a radius of about 1, miles 2, kilometers , about 85 percent of the planet's radius.

There is evidence that it is partly molten or liquid. Mercury's outer shell, comparable to Earth's outer shell called the mantle and crust , is only about kilometers miles thick.

Mercury's surface resembles that of Earth's Moon, scarred by many impact craters resulting from collisions with meteoroids and comets.

Craters and features on Mercury are named after famous deceased artists, musicians, or authors, including children's author Dr. Seuss and dance pioneer Alvin Ailey. Very large impact basins, including Caloris miles or 1, kilometers in diameter and Rachmaninoff miles, or kilometers in diameter , were created by asteroid impacts on the planet's surface early in the solar system's history.

While there are large areas of smooth terrain, there are also cliffs, some hundreds of miles long and soaring up to a mile high.

They rose as the planet's interior cooled and contracted over the billions of years since Mercury formed. Most of Mercury's surface would appear greyish-brown to the human eye. The bright streaks are called "crater rays. The tremendous amount of energy that is released in such an impact digs a big hole in the ground, and also crushes a huge amount of rock under the point of impact.

Some of this crushed material is thrown far from the crater and then falls to the surface, forming the rays. Fine particles of crushed rock are more reflective than large pieces, so the rays look brighter. The space environment — dust impacts and solar-wind particles — causes the rays to darken with time. Temperatures on Mercury are extreme. During the day, temperatures on the surface can reach degrees Fahrenheit degrees Celsius. Because the planet has no atmosphere to retain that heat, nighttime temperatures on the surface can drop to minus degrees Fahrenheit minus degrees Celsius.

Mercury may have water ice at its north and south poles inside deep craters, but only in regions in permanent shadows. In those shadows, it could be cold enough to preserve water ice despite the high temperatures on sunlit parts of the planet. Instead of an atmosphere, Mercury possesses a thin exosphere made up of atoms blasted off the surface by the solar wind and striking meteoroids.

The planet's weak magnetic field helps to funnel the material from the day to night side, but is not strong enough to explain the distributions observed. While Earth's magnetic field shields the planet from many of the sun's charged particles, the field surrounding Mercury is too weak.

While some of the particles kicked up by the sun fall back onto the planet, some of it drifts away, forming a comet-like tail behind the planet. Sodium and calcium populate the material. Burger's models revealed the prevalence of PSD in creating the planet's tail. Speaking of comets, the wandering chunks of ice also affect the planet's atmosphere. In a separate study, Burger and his colleagues found a pattern for calcium that repeated over Mercury's short orbit.

Killen and colleagues then worked to figure out what happened when Mercury plowed through the cloud of debris known as zodiacal dust that surrounds the sun.

Most of the calcium could be explained by the cloud, but the team found that Comet Encke's short 3. Apparently, comet streams can have a huge, but periodic, effect. With virtually no atmosphere, Mercury feels very little in terms of traditional weather. It does feel the presence of solar weather, with the constant ebb and flow of the solar wind bombarding its surface. The lack of atmosphere also contributes to the planet's wild temperature extremes.

On other planets, the atmosphere functions as a blanket, helping to redistribute heat somewhat. But on Mercury, the thin atmosphere does nothing to stabilize the incoming solar rays—and because the distance to Mercury from the sun is so small, the day side of the planet feels the heat keenly, while the night side, turned from the sun, only registers the cold. Scientists find that the molecules in the atmosphere are constantly being restored and replaced, so the atmosphere is never quite empty.

Scientists suggest that dust and rocks kicked into the air by wind or meteorites may be giving the atmosphere its molecules, or solar winds could be kicking up dust and gas. Mercury also has a magnetic field, and has two poles. While the magnetic field is nearly times weaker than our own on Earth, this magnetic fields helps hold its atmosphere in place by reducing the impact of the solar winds.

Mercury is not like that. Instead, the atmosphere of Mercury is unstable and constantly shifting.