Solar day in mercury lasts two years on the planet; understand

In the alignment of the seven planets of the solar system on February 28, one of them particularly drew the attention of observers: Mercury. This was because he was at his point of maximum elongation, that is, the greatest angular separation from the sun.

Being away from the brilliance of our star, the smallest planet in the solar system could be easily observed after sunset, especially in the northern hemisphere, but the observation window was short, as Mercury was shortly after twilight.

However, being able to observe the planet closest to the sun with the naked eye is always exciting, mainly because the fast celestial messenger (mercury in Greek mythology) is one of the least studied planets in the solar system.

Strong solar gravity and intense heat make it difficult to send and operation of spacecraft in the region. In addition, the proximity to the sun causes the planet can only be observed in short periods at dawn or dusk when it is near the horizon.

Still, Mercury has already been visited by two terrestrial missions:

• Mariner 10 probe, which mapped 45% of its surface in 1974 and 1975; and
• Messenger, first to orbit the planet in 2011-2015.

In addition to the two missions of NASA, Becolombo, a joint mission of the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA), has already made six flyfs on the planet and is scheduled to enter orbit in November 2026.

Mercury has many details and its study offers a unique view of the formation and evolution of planets, solar systems and the universe itself. Meet below five of them.

A solar day in mercury lasts two mercurian years

In terms of translation, Mercury is the fastest planet in the solar system, completing a lap around the sun in approximately 88 terrestrial days, at an average speed of 170,500 km/h.

Rotation, in turn, is extremely slow compared to that of the earth. To rotate completely around the axis itself, Mercury takes about 59 terrestrial days.

However, due to the combination of slow rotation with a fast translation, a complete solar day (from a sunrise to the next) in mercury lasts approximately 176 terrestrial days. This means that One day in Mercury corresponds to two years .

Mercury is one of the hottest planets, but also colder in the solar system

Being the closest planet to the sun, Mercury is expected to be one of the hottest planets (although this title belongs to Venus). During the day, the surface temperature reaches 427 ° C.

But, due to the lack of an atmosphere that can retain this heat, Night temperatures on the planet fall to -179 ° C . To get an idea of ​​how extreme this temperature is, just say that the coldest planet in the solar system, Uranus, with an average of -224 ° C, is 2.9 billion kilometers from the sun.

Even near the sun, Mercury has large deposits of water

Despite being closer to the sun than the other planets, and having scorching temperatures when its surface receives solar radiation, Mercury has large water deposits in some craters near its north and south poles.

Discovered by Messenger in 2012, water in permanently shaded areas of the planet reinforces the idea that these frozen deposits can be common, even on inhospitable planets for life as we know it .

Big and metallic core is making mercury shrink

Exceptionally large, the mercury core makes up about 85% of the planet’s diameter, which is almost triple of the earth’s nucleus, which represents only 30%. It is mainly composed of iron, solid internally and melted outside.

Although previous theories suggested that impacts over billions of years have removed part of the planet’s crust and left it with an abnormally large metallic core, a recent study indicates that solar magnetic field may have been responsible for attracting metal particles.

Cooling and contraction of this core over time pulled the planet’s crust inwards (as the solid nucleus occupies less volume), causing fractures and geological changes. Therefore, Mercury is the only planet in the solar system that is shrinking .

Mercury has no atmosphere, but has a thin exshere

The statement that the smallest planet in the solar system has an exosphere may seem contradictory. After all, this region is the outermost of an atmosphere, that does not exist in mercury .

In the analogy that a planetary atmosphere would be like an onion with several dense and well -defined layers, the “mercurian onion” would have only the outer film. In fact, such a thin and sparse shell that could not even be called continuous.

In addition to not forming an envelope, the mercury exosphere has particles that do not interact with each other, it does not offer the protective effects of a real atmosphere and is in a constant process of loss and replacement of oxygen particles, sodium, hydrogen, helium and potassium.

See also: joint euro-japanese mission first fly and photograph mercury

This content was originally published on solar day in Mercury last two years on the planet; Understand on CNN Brazil.

Source: CNN Brasil