Venus is the second planet of our Solar system and the brightest object in the night sky after the Moon. The only “female” planet (apart from Earth), got its name from the Roman goddess of love and fertility. We do not know who discovered Venus, but Babylonians astronomers mentioned Venus for the first time in the second millennium BC. In the early 20th century, science fiction was presenting Venus as a tropical paradise. This made people refer to Venus as our twin sister planet. But, as our knowledge on Venus progressed, we found that if Venus is our twin sister, then she is our dark and strange sibling. Exploration of Venus gave us many interesting results over the last 50 years. So, let’s see the interesting facts about Venus, that make the planet unique.
Venus planet info
If you see the basic information of Venus, you may agree that it could be our sister planet. Venus has a radius of 6,050 km (95% of Earth’s), a mean density of 5.243 g/cm3 (Earth’s density is 5.51 g/cm3), and a mass of 4.84×1024 kg (81.5% of Earth’s). All the above correspond to a gravitational acceleration of 8.82 m/s2 (9.81 m/s2 on Earth). At least, in theory, such numbers make Venus our twin sister, but Venus has some features that make the planet extraordinary.
Venus completes an orbit around the Sun in 224.7 days, but a Venusian day lasts 243 days. This makes Venus the planet with the longest day in the Solar System. If you think that is not strange enough, Venus has more. The planet orbits around its axis clockwise (retrograde), meaning that the Sun rises from the west and sets in the east. It is still a mystery why Venus orbits in a clockwise orientation.
One hypothesis is that Venus spins the same way it always has, but at some point, the planet flipped over. Another model suggests that during its formation, two planetesimals collided. The outcome of the collision was the formation of Venus. This model although it can provide an explanation for the retrograde motion of the planet, and the lack of water (the collision overheated the planetesimals), but the length of the day still remains unknown.
Atmospheric composition of Venus
Venus claims many first positions in our Solar system. During the 60s, the tremendous competition between the Soviet Union and the U.S.A., led to the first probe visiting another planet. In December 1962, Mariner 2 flew by Venus and returned data from its atmosphere. Between 1967 and 1975, the Soviet Union sent a series of probes to Venus for studying the atmosphere and surface of the planet.
From observations we found that Venus’ atmosphere is composed of carbon dioxide (96.5%), nitrogen (3.5%), with traces of other gases (argon, sulfur dioxide). Additionally, the atmosphere of Venus has opaque clouds of sulfuric acid. Due to these, it is impossible to observe the surface of Venus with ground based telescopes or even with probes that orbit the planet. These clouds create acid rain, but due to the high temperature the liquid sulfuric acid evaporates before it can reach the surface.
Based on the probes that landed on the surface of the planet, the surface pressure of Venus is 90 times that of Earth. If you would like to experience the same pressure on Earth, you need to dive at a depth of 900 meters. If you think this is not enough, space-probes detected storms with wind speeds up to 370 km/h, making even the presence of probes a challenge.
Who’s the hottest planet in our Solar system?
The mean surface temperature is around 470°C (880°F), with small variations around the planet. This makes Venus the hottest planet in the Solar system, and responsible for this is the enhanced greenhouse effect. All these combined, make the entire planet hostile even for equipment (each of the Venera probes, could send data back to Earth for around 50 minutes).
Surface characteristics and internal structure of Venus
During the late 80s and early 90s, Magellan, a U.S. probe entered into orbit around Venus to study the surface of the planet. Through radar observations, we found that the surface of Venus has numerous volcanoes. Venus has more volcanoes than Earth, and there are over 150, which are over 100 km across. This does not mean that Venus is more active geologically than Earth, but it is evidence of an old surface. Earth’s crust is much younger, due to plate tectonics activity, and the presence of water. For years we thought all volcanoes in Venus were dead, but in January 2020, astronomers found evidence of volcanic activity.
Based on Venus’ similarity with the Earth, we believe that the internal structure of the planet is similar. So most likely, Venus has a core, a mantle, and a crust. Just as our Earth’s core, the core of Venus is partially liquid. The fundamental difference with the Earth is that there is no evidence of plate tectonics. This translates to a very strong crust, which is attributed to the lack of water. As an effect of this, Venus’ interior does not cool like Earth. The absence of a cooling mechanism in the interior of the planet, can explain why Venus does not have a magnetic field like Earth.
Summary and future missions to Venus
It seems that our twin sister is diverse from our planet. Venus comes very close to what we call hell, but still, many questions remain unanswered. These have to do with the formation of its atmosphere, the structure of the planet, and its rotation. Perhaps, the future missions to Venus will spread more light on our neighboring planet. One of the most promising, is the revival of Venera in 2025, where an orbiter, atmospheric balloons, and a lander, will observe the planet. The other is NASA’s Zephyr, a rover that will land on Venus for the first time.
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