Venus could have swallowed its own moon due to its slow rotation.
Venus could have its own moon, but over time it could fall on the planet due to its extremely slow rotation. Computer simulations have shown that the satellite in such conditions would gradually approach Venus and eventually collide with its surface. About why Venus could lose the moon and how this could affect the evolution of the planet, in the material "Izvestia".
Could Venus have its own moon
Venus is similar to Earth in size, mass, and structure, but unlike our planet, it does not have a natural satellite. Previously, scientists have considered several explanations for this difference. According to one hypothesis, Venus could have once had a moon that was destroyed in a major collision. Another suggested that the planet had never experienced a collision capable of forming a satellite.
A new study published in The Astrophysical Journal suggests a different scenario. Stephen Kane, an astrophysicist at the University of California at Riverside, suggested that Venus could indeed have a moon, but could not preserve it for a long time.
Stephen Kane
My research shows that Venus didn't need a catastrophe to get to the state we see today.
According to him, the gravity of the planet, combined with the speed of its rotation, could naturally lead to the satellite falling to the surface. However, the study does not prove that Venus actually had a moon. The simulation results only show that such a satellite would not be able to stay in orbit for a long time under certain conditions.
Why could the moon have fallen on Venus
The main factor in the proposed model was the speed of rotation of the planet. Venus rotates around its axis exceptionally slowly: one complete revolution takes about 243 Earth days. By comparison, the Earth rotates in about 24 hours.
The mechanism can be compared to the modern Earth—Moon system. Our planet rotates fast enough that some of the energy of its rotation is gradually transferred to the Moon. As a result, the satellite is slowly moving away from Earth — by about four centimeters per year. Scientists can accurately measure this movement thanks to the reflectors left on the Moon's surface during the "Apollo" missions.
Venus has the opposite situation. Due to the very slow rotation of the planet, the hypothetical moon should not have gradually moved away from it. The gravitational interaction, on the contrary, would force the satellite to slowly spiral inwards, approaching the surface.
Thus, the fate of the moon would depend not only on its own characteristics, but also on the speed of rotation of the planet. The larger the satellite would be, the faster, according to the simulations, it could eventually collide with Venus.
How scientists modeled the fall of a satellite
To test the hypothesis, the researcher created a computer model describing the gravitational interaction of the planet and the satellite. First, he tested it on the Earth—Moon system. The model was able to reproduce the known evolution of our system, after which it was applied to Venus.
For Venus, the scientist changed the planet's rotation speed and modeled hypothetical moons of different masses. The calculations considered moons whose mass ranged from half the mass of the Earth's moon to ten of its masses. In most scenarios, the result was the same: the satellite gradually approached Venus and eventually collided with the planet. More massive moons reached the surface faster.
Stephen Kane
When I made the discovery, I was shocked. I thought that the wide range of scenarios I was considering would inevitably lead to different outcomes. But everything went roughly in the same direction.
However, scientists do not yet know whether Venus actually had a moon. To confirm the hypothesis, additional data on the internal structure and geological history of the planet will be required.
Could the fall of the moon have changed Venus
Direct traces of the alleged collision are not easy to detect. The surface of Venus has changed significantly during its existence: about 80% of its surface has approximately the same geological age, which is associated with a large-scale process of surface renewal about a billion years ago. Therefore, the ancient evidence of a possible collision could have been erased.
The researchers suggest that some of the information could have been preserved deep inside the planet. On Earth, scientists have discovered unusual structures in the bowels that may be related to the giant collision that led to the formation of the Moon. Similar studies of the internal structure of Venus in the future could help test the hypothesis about its former satellite.
The possible fall of the moon would have serious consequences for the planet itself. The collision would have transferred a huge amount of energy and angular momentum to Venus, which could have affected its rotation, geological activity, and climate. If in the distant past there were oceans on Venus or other conditions more favorable for life, such an event could change the further evolution of the planet.
The hypothesis is also important for studying planets outside the Solar system. Scientists consider the presence of the moon as one of the factors that can influence the long-term evolution of the planet, but it is not yet known whether a large satellite is a necessary condition for the emergence or preservation of life.
Stephen Kane
It seems to me that having a moon has its advantages, but it is not a prerequisite for habitability. The moon has certainly changed the evolution of the earth over time, but we don't fully know how important this role is.
Переведено сервисом «Яндекс Переводчик»
