Why does the environment of Venus look so different, even though it is the same size as the Earth

金星は地球と同じような大きさにもかかわらず、太陽に近いため環境が大きく異なります。 これにより、形成中の微惑星の衝突速度が速くなり、表面の 82% が溶け、内部が大幅に加熱されました。 その結果として生じる高い表面温度と固体磁場の欠如は、金星の表面年齢の若化、火山活動の増加、そして生命にとって住みにくい条件の一因となります。(English) Despite being similar in size to Earth, Venus has a vastly different environment due to its proximity to the Sun. This led to faster collision velocities of planetesimals during its formation, melting 82% of its surface and significantly heating its interior. The resulting high surface temperatures and lack of a solid magnetic field contribute to Venus' younger surface age, increased volcanic activity, and inhospitable conditions for life.

Why does the environment of Venus look so different, even though it is the same size as the Earth?

1)

The Earth's and Venus' diameters are 12,742 km and 12,104 km, respectively, a difference of only about 5%.

However, a day on Venus is absurdly long (243 days), while Mars is much closer to Earth (24 hours 37 minutes). These three brothers of the Solar System's rocky planets are unique, with similarities and differences.

2)

The difference between the terrestrial and Martian environments can largely be explained by the difference in size (the diameter of Mars is about half that of the Earth). It is difficult to explain why.

3)

A team of researchers led by scientists at the Southwest Research Institute in the United States provided a clear answer to this naive question about Venus.

A paper detailing the research has been published on the US science website Nature Astronomy, and Yale University Professor Jun Korenaga is a research team member.

Venus has a relatively young surface age of 200 million to 1 billion years compared to Earth. The reason for this remains a mystery to scientists.

4)

Unlike Earth, Venus does not have a strong magnetic field. Despite this, there are 60 times more active volcanoes on the surface of Venus than on Earth.

On Earth, a strong magnetic field and the presence of a disproportionately large satellite, the Moon, drive active volcanic activity. Still, the driving force behind Venusian volcanism has been a mystery.

5)

The new study suggests that Venus has a younger surface age and more volcanic activity than Earth because it orbits closer to the Sun.

As a result, the collision velocity of the planetesimals that repeatedly collided with Venus in the early stages of its formation was much faster than that of the planetesimals that collided with Earth.

They conclude that the temperature rise at the surface of Venus was so significant that 82% of its surface was melted by the impact, heating the interior considerably.

6)

While the Earth has a high internal temperature and an excellent surface layer, the surface layer of Venus is kept extremely hot, so the surface age of Venus is likely to have remained young.

The high surface temperatures may also cause Venus to overheat, making it difficult for life to form.

Why does Venus' environment look so different despite being the same size as Earth? 

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First measurement of temperature distribution in the Venusian atmosphere The University of Tokyo

https://www.zaikei.co.jp/article/20200301/555309.html

//Summary -Level-C2//

The University of Tokyo has successfully measured the temperature distribution and atmospheric stability in Venus's atmosphere for the first time. Using the Venus probes Akatsuki and Venus Express and the radio occultation technique. The team observed temperature variations with altitude and latitude. They discovered an unstable atmospheric region at the equator and hazardous areas extending below the cloud layer at the poles. These findings will aid in constructing an atmospheric circulation model for Venus.

1)

On 27 February, the University of Tokyo announced that it had successfully measured the temperature distribution and atmospheric stability in the lower Venusian to mesosphere for the first time in history.

2)

Venus is similar to and different from Earth

While Venus and Earth are similar in mass and size, their atmospheric environments differ. While Earth's atmosphere is mostly nitrogen and oxygen, Venus' atmosphere is mostly carbon dioxide.

The surface of Venus has a high temperature and pressure environment, with a temperature of 460 degrees and an atmospheric pressure of 90 atmospheres. Venus is also unique in that clouds of concentrated sulphuric acid cover it.

3)

Until now, observations of Venus have been made using large telescopes and artificial satellites on the ground. However, observing the atmospheric structure below the cloud layer has been difficult because Venus is covered in thick clouds.

4)

Observing the Venusian atmosphere using the Doppler effect

A research group at the University of Tokyo used the Venus probes Akatsuki and Venus Express to keep the temperature distribution in the atmosphere from an altitude of 40 to 85 kilometres over the globe.

A technique called radio occultation, which uses the Doppler effect, has made it possible to measure the altitude distribution of Venusian temperature with high precision and high resolution.

Observations using this method have been made before, but this is the first time in history that data has been obtained over the entire planet of Venus.

5)

As a result of the observation, it was found that the temperature decreases with increasing latitude below an altitude of 60 kilometres, but the opposite trend is observed above this altitude.

It was also shown that there is a locally cold region, called the "cold collar'', around 65 degrees latitude.

6)

When the research group calculated the atmosphere's stability from the temperature distribution, they found a difference in the stable region of the atmosphere at 70 degrees latitude.

On the equatorial side, there was an unstable region of the atmosphere at an altitude of 50 to 55 km. On the polar side, however, dangerous areas of the atmosphere were found to extend below the cloud layer.

7)

The research group expects that the results of this research will contribute to constructing an atmospheric circulation model for Venus. It will also help us understand the mechanism of the clouds that cover Venus.