Retrograde motion of celestial bodies is one of the mysteries of space. Scientists have long known which planet rotates the other way in the solar system, but scientific debate about why it does this is still going on.
The planets of the solar system. Credit: Origins.org
How is retrograde rotation obtained?
If you look at our system "from above", from the side of the conditional North Pole of the world, you can see that all bodies move around the central star in one direction. In addition, they all rotate around their axes counterclockwise, but several bodies do this in the opposite direction.
Among them are Venus and Uranus, as well as Pluto, which recently lost its status as a planetary object, its natural moon Charon and the Neptunian satellite Triton. The rotation of these bodies is called retrograde.
In this case, the direction of rotation of Venus nevertheless coincides with the terrestrial, Mercurian and others, but is perceived as reversed due to the fact that the planet is practically turned upside down.
There are at least 3 possible reasons why some objects are spinning retrograde:
- changes in the gravitational field of the planet itself and the effect of gravity of the surrounding astronomical bodies;
- the influence of powerful solar tides;
- a sharp change in the direction of rotation as a result of collisions with other space elements.
There are several ways to identify the direction of rotation of the planets: they are observed in radio telescopes from the Earth and from space observatories in orbits, and mathematical calculations are carried out.
Rotation axis tilt
The direction of rotation of the planets is indicated by the inclination of their axes. It is understood as the angle between the conditional line around which the proper rotation of the celestial body takes place, and the perpendicular to the ecliptic - the plane along which the circumsolar orbit lies.
If this angle is in the range from -90 to + 90 °, it is believed that the planet has direct torsion, which coincides with the general direction of rotation of the vast majority of cosmic bodies.
When the angle is in the range of 90-270 °, the rotation is retrograde.
The natural moons of planets revolving around the Sun have the same tilt.
Only they operate with a different angle - between the axis of rotation of the satellite and the plane crossing its host planet along the equator.
What makes Venus spin differently
Of all the atypically rotating bodies in our system, the second planet from the Sun is the most studied.
One of the hypotheses explaining the reasons for its retrograde rotation says that at the moment of the formation of solar planetary bodies from a rotating gas and dust disk, a clot of dust and energy, from which Venus was to be born, collided with the emerging Mercury, which is why it suddenly began to spin in the direction opposite to the rest of the protoplanets - clockwise.
Another theory suggests the following: the culprit for Venus's retrograde rotation was its too high and dense atmosphere - it slows down rotation, spinning the planet in the opposite direction.
Another interesting version says that the body was turned over by the powerful gravitational tides provoked by the influence of the central luminary and the friction caused by them between the planetary mantle and the core.
Perhaps the dense atmosphere is causing Venus to rotate the other way. Credit: V-kosmose.com
The large tilt of the Venus axis, close to 180 °, is an obstacle to the change of the seasons on the planet - summer lasts here all the time. The planet makes a full orbital revolution in 225 Earth days, the daily rotation takes as much as 243 days. For this cosmic body, sidereal days last longer than a solar year.
"Lying planet"
If the inclination of the Venus axis is 177 ° and it is "inverted", then the seventh planet from the Sun with a similar parameter of 98 ° is called "lying". “Uranus rotates lying down” - scientists say about it.
There is a kind of change of seasons here, each of which lasts 42 years. At the moment of the solstice, winter or summer, one Uranian pole is directed to the central luminary of our system, and a polar day is observed in the adjacent hemisphere. The opposite region of the celestial body is directed towards the trans-Neptunian objects; the polar night lasts near it.
At the equator at this time, there is a rapid change in the dark and daylight hours. Uranus makes a complete revolution around the Sun in 84 years, a revolution around its axis - in a little more than 17 Earth hours.
Why Pluto is retrograde
Scientists have reason to believe that Pluto is part of a massive object that disintegrated after an explosion, torn out for some reason from the bowels of neighboring Neptune. The second fragment of this body, the larger one, remained in the Neptunian orbit, becoming a natural satellite of the planet Triton.
Now it is also a smaller piece that has gained greater speed and flew away from the influence of the "Blue Giant", which has become an independent dwarf planet Pluto - bodies rotating in the same direction, retrograde with respect to their neighbors.
Pluto is the most distant, former planet of the Solar System. Credit: NASA
A day here lasts almost 153 Earth hours, and in terms of the length of a year, this body holds the record for the part of the cosmos studied by us - it is equal to 248 years on our planet.
I was interested in the topic of what rotates clockwise and what rotates counterclockwise. Very often you can find in the world a lot of things based on vortices, spirals, twists, having a right spin of rotation, that is, twisted according to the rule of the gimbal, the rule of the right hand, and the left spin of rotation.
Spin is called the proper angular momentum of a particle. In order not to complicate the note with theory, it is better to see once. Slow waltz element - right spin turn.
For many years there has been a discussion among astronomers about the direction in which the spiral galaxies rotate. Do they rotate, dragging spiral branches with them, that is, twisting? Or do they rotate with the ends of the spiral branches forward, unwinding?
At the present time, however, it is becoming clear that observations support the hypothesis of the twisting of the spiral branches during rotation. American physicist Michael Longo was able to confirm that most of the galaxies in the Universe are oriented to the right side (right spin), i.e. rotates clockwise when viewed from its north pole.
The solar system rotates counterclockwise: all planets, asteroids, comets rotate in the same direction (counterclockwise when viewed from the north pole of the world). The sun rotates on its axis counterclockwise when viewed from the north pole of the ecliptic. And the Earth (like all the planets of the solar system, except Venus and Uranus) rotates around its axis counterclockwise.
The mass of Uranus, sandwiched between the mass of Saturn and the mass of Neptune, under the influence of the rotational moment of the mass of Saturn, got clockwise rotation. Such an impact from Saturn could have occurred for the reason that the mass of Saturn is 5.5 times the mass of Neptune.
Venus rotates in the opposite direction than almost all planets. The mass of the planet Earth spun the mass of the planet Venus, which got clockwise rotation. Therefore, the diurnal periods of rotation of the planets Earth and Venus should also be close to each other.
What else is spinning, spinning?
The snail's house spins clockwise from the center (i.e. rotation here goes with a left spin, counterclockwise).
Tornadoes, hurricanes (winds centered in the area of \u200b\u200bthe cyclone) blow counterclockwise in the Northern Hemisphere and obey the centripetal force, while the winds centered in the area of \u200b\u200bthe anticyclone blow clockwise and have centrifugal force. (In the Southern Hemisphere, everything is exactly the opposite.)
The DNA molecule is twisted into a right-sided double helix. This is because the backbone of the DNA double helix is \u200b\u200bcomposed exclusively of right-handed deoxyribose sugar molecules. Interestingly, during cloning, some nucleic acids change the direction of twisting of their helices from right to left. In contrast, all amino acids are twisted counterclockwise to the left.
Flocks of bats, flying out of caves, usually form a "dextrorotatory" vortex. But in caves near Karlovy Vary (Czech Republic), for some reason, they circle in a spiral, twisted counterclockwise ...
When one cat sees sparrows (these are her favorite birds), the tail turns clockwise, and if these are not sparrows, but other birds, then it turns counterclockwise.
And if we take Humanity, then we see that they are going counterclockwise: all sporting events (auto racing, horse races, running at the stadium, etc.) After some centuries, athletes noticed that it is much more convenient to run this way. Running the stadium counterclockwise, the athlete with his right foot makes a wider step than he would have done with his left, since the range of motion of the right foot is several centimeters larger. In most armies of the countries of the world, a circle is turned over the left shoulder, that is, counterclockwise; church rituals; the movement of cars on the roads in most countries of the world, with the exception of the UK, Japan and some others; at school the letters "o", "a", "b", etc. - from the first grade they teach to write counterclockwise. In the future, the overwhelming part of the adult population draws a circle, stirring with a spoon with sugar in a mug counterclockwise.
And what follows from all this? Question: Is counterclockwise rotation natural for humans?
As a conclusion: the Universe moves clockwise, but the solar system is against, the physical development of all living things is clockwise, consciousness is against.
We have been studying the solar system for hundreds of years, and one would assume that we have the answers to all the frequently asked questions about it. Why the planets rotate, why they are in such orbits, why the Moon does not fall to the Earth ... But we cannot boast of this. To be convinced of this, it is enough to look at our neighbor, Venus.
Scientists began to study it closely in the middle of the last century, and at first it seemed relatively dull and uninteresting. However, it soon became clear that this is the most natural hell with acid rain, which also rotates in the opposite direction! More than half a century has passed since then. We learned a lot about the climate of Venus, but we still have not been able to understand why it does not rotate like everyone else. Although there are many hypotheses on this score.
In astronomy, rotation in the opposite direction is called retrograde. Since the entire solar system was formed from one rotating gas cloud, all the planets move in orbits in the same direction - counterclockwise, if you look at this whole picture from above, from the side of the North Pole of the Earth. In addition, these celestial bodies revolve around their own axis - also counterclockwise. But this does not apply to the two planets of our system - Venus and Uranus.
Uranus actually lies on its side, most likely due to a couple of collisions with large objects. Venus rotates clockwise, and this is even more problematic to explain. One of the early hypotheses suggested that Venus collided with an asteroid, and the impact was so strong that the planet began to spin in the other direction. This theory was thrown into the discussion of the interested public in 1965 by two astronomers who processed radar data. Moreover, the definition "thrown in" is in no way humiliation. As the scientists themselves stated, the quote: “This possibility is dictated only by the imagination. It is hardly possible to get evidence to support it. " Extremely convincing, isn't it? Be that as it may, this hypothesis does not stand up to the test of simple mathematics - it turns out that an object, the size of which is sufficient to reverse the rotation of Venus, will simply destroy the planet. Its kinetic energy will be 10,000 times more than it takes to smash the planet into dust. In this regard, the hypothesis was sent to the distant shelves of scientific libraries.
It was replaced by several theories, which were based on some kind of evidence base. One of the most popular, proposed in 1970, suggested that Venus rotated in this way originally. It's just that at some point in her story, she turned upside down! This could be due to the processes taking place inside Venus and in its atmosphere.
This planet, like the Earth, is multi-layered. It also has a core, mantle and crust. During the rotation of the planet, the core and mantle experience friction in the area of \u200b\u200btheir contact. The atmosphere of Venus is very thick, and thanks to the heat and the attraction of the Sun, it is exposed, like the rest of the planet, to the tidal effect of our star. According to the described hypothesis, friction of the crust with the mantle, coupled with atmospheric tidal fluctuations, created a torque, and Venus, having lost stability, toppled over. Simulations have shown that this could only happen if Venus had an axis tilt of about 90 degrees since its formation. Later, this number decreased slightly. In any case, this is an extremely unusual hypothesis. Imagine a tumbling planet! This is some kind of circus, not space.
In 1964, a hypothesis was put forward, according to which Venus changed its rotation gradually - it slowed down, stopped, began to spin in the other direction. This could have been triggered by several factors, including interactions with the sun's magnetic field, atmospheric tides, or a combination of forces. The atmosphere of Venus, according to this theory, spun in the other direction of the first. This created an effort that at first slowed down Venus and then spun retrograde. As a bonus, this hypothesis also explains the long duration of the day on the planet.
In the dispute of the last two explanations, there is no clear favorite yet. To understand which one to give preference to, we need to know much more about the dynamics of early Venus, in particular about the speed of its rotation and the tilt of the axis. According to an article published in 2001 in the journal Nature, Venus is more likely to overturn if it had a large initial rotational speed. But, if it was less than one revolution in 96 hours with a small axial tilt (less than 70 degrees), the second hypothesis looks more plausible. Unfortunately, it is rather difficult for scientists to look into the past four billion years. Therefore, until we invent a time machine or carry out unrealistically high-quality computer simulations, progress in this matter is not expected.
It is clear that this is not a complete description of the debate regarding the rotation of Venus. So, for example, not so long ago the very first of the hypotheses described by us received an unexpected development - the one that comes from 1965. In 2008, it was suggested that our neighbor could have turned in the opposite direction while she was still a small, unreasonable planetesimal. An object about the same size as Venus itself should have crashed into it. Instead of the destruction of Venus, the merger of two celestial bodies into one full-fledged planet would follow. The main difference from the original hypothesis here is that scientists may have evidence in favor of this turn of the situation.
According to what we know about the topography of Venus, there is very little water on it. Compared to the Earth, of course. Moisture could disappear from there as a result of a catastrophic collision of cosmic bodies. That is, this hypothesis would also explain the dryness of Venus. Although there is also, as ironic as it may sound in this case, pitfalls. Water from the surface of the planet could have evaporated in a banal way under the rays of the hot Sun here. To clarify this issue, a mineralogical analysis of rocks from the surface of Venus is needed. If water is present in them, the hypothesis of an early collision will disappear. The problem is that such analyzes have not yet been carried out. Venus is extremely unfriendly to the robots that we send to her. Destroys without hesitation.
Be that as it may, building an interplanetary station with a Venus rover capable of operating here is still easier than a time machine. Therefore, let's not lose hope. Perhaps humanity will receive an answer to the riddle of the "wrong" rotation of Venus during our lifetime.
Planet Venus interesting facts. Some you may already know, others should be completely new to you. So read on and learn new interesting facts about the "morning star".
Earth and Venus are very similar in size and mass, and they revolve around the Sun in very similar orbits. Its size is only 650 km less than the size of the Earth, and its mass is 81.5% of the Earth's mass.
But that's where the similarities end. The atmosphere is 96.5% carbon dioxide, and the greenhouse effect raises temperatures up to 461 ° C.
2. The planet can be so bright that it casts shadows.
Only the Sun and Moon are brighter than Venus. Its brightness can range from -3.8 to -4.6 magnitudes, but it is always brighter than the brightest stars in the sky.
3. Hostile atmosphere
The mass of the atmosphere is 93 times that of the Earth's atmosphere. The surface pressure is 92 times that of the Earth. It is like diving a kilometer under the surface of the ocean.
4. It rotates in the opposite direction compared to other planets.
Venus rotates very slowly, the day is 243 Earth days. Even stranger is that it spins in the opposite direction compared to all other planets in the solar system. All planets rotate in a counterclockwise direction. Except for the heroine of our article. It rotates clockwise.
5. Many spacecraft have managed to land on its surface.
In the midst of the space race, the Soviet Union launched the Venus series of spacecraft and some successfully landed on its surface.
Venera 8 was the first spacecraft to land on the surface and transmit photographs to Earth.
6. People are used to thinking that there are "tropics" on the second planet from the Sun.
While we sent the first spacecraft to study Venus from close range, no one really knew what was hidden below under the thick clouds of the planet. Science fiction writers dreamed of a lush tropical jungle. The hellish temperature and dense atmosphere surprised everyone.
7. The planet has no satellites.
Venus looks like our twin. Unlike Earth, it has no moons. Mars has satellites, and even Pluto has satellites. But she ... no.
8. The planet has phases.
Although it looks like a very bright star in the sky, if you can look at it with a telescope, you will see something different. When looking at it through a telescope, you can see that the planet goes through phases like the moon. When it is closer, it looks like a thin crescent moon. And at the maximum distance from the Earth, it becomes dim and in the form of a circle.
9. There are very few craters on its surface.
While the surfaces of Mercury, Mars and the Moon are littered with impact craters, there are relatively few craters on the surface of Venus. Planetary scientists believe that its surface is only 500 million years old. Constant volcanic activity smooths out and removes any impact craters.
10. The last ship to explore Venus is the Venus Express.
Earth and Venus are similar in size and mass. In addition, they revolve around the Sun in very similar orbits. Venus is only 650 km smaller than Earth. The mass of Venus is 81.5% of the mass of the Earth.
But that's where the similarities end. The atmosphere of Venus is 96.5% carbon dioxide (CO2), the temperature on the planet is absolutely unsuitable for flora and fauna, because it reaches 475 ° C. Venus also has very high pressure, which will crush you if you suddenly want to walk on the surface of this planet.
2. Venus is so bright that it can form shadows.
Astronomers measure the brightness of objects in the night sky by their magnitude. Only the Sun and Moon are brighter than Venus. Its brightness can range between -3.8 and -4.6 magnitudes, but obviously, it is always brighter than any of the brightest stars in the sky.
Venus can be so bright that it can actually cause shadows. Wait for a dark night when there is no moon in the sky, and check it directly for yourself.
3. The atmosphere of Venus is extremely hostile.
Although Venus is similar to Earth in size and mass, its atmosphere is unique in its own way. The mass of the atmosphere is 93 times greater than the mass of the Earth's atmosphere. If you suddenly found yourself on the surface of Venus, you would experience 92 times the pressure relative to the pressure that acts on you on Earth. This is the same as being almost a kilometer below the surface of the ocean.
And if the pressure doesn't kill you, the heat and toxic chemicals will surely do it. Temperatures on Venus can reach 475 ° C. Thick clouds of sulfur dioxide on Venus create precipitation of sulfuric acid. This is a really hellish place ...
4. Venus rotates in the opposite direction.
While a day on Earth takes only 24 hours, a day on Venus is equal to our 243 Earth days. But even stranger, Venus rotates in the opposite direction compared to the rest of the planets in the solar system. If you had a chance to look at the planets of the solar system from above, then you would see that they all rotate counterclockwise. Except for Venus, which rotates clockwise.
5. Many missions have landed on the surface of Venus.
You probably thought that it would be impossible to land any apparatus on the surface of such a hellish world. And you are partially right. During the space race, the Soviet Union began a series of expeditions to the surface of Venus. But the engineers underestimated how awful the planet's atmosphere is.
The first spaceships were crushed when they entered the atmosphere of Venus. But finally, the automated research space station Venera-8 became the first spacecraft to be on the surface of Venus, to take and transmit images to Earth. Subsequent missions took longer, and even transmitted the first color images of the surface of Venus.
6. People thought that Venus was covered with rainforest.
Until the United States and the USSR took up the exploration of Venus by spacecraft, no one really knew what was hidden under the thick clouds of the planet. Science fiction writers have described the planet's surface as a lush tropical jungle. The hellish temperatures and dense atmosphere surprised everyone.
7. Venus has no natural satellites.
Unlike, say, Earth, Venus has no natural satellites. Mars has two, and even Pluto has. But not Venus.
8. Venus has phases.
Looking at Venus through a telescope, you can see that the planet is in one phase or another, like the moon. When Venus is closest, it actually looks like a thin crescent moon. As Venus gets dimmer and more distant, you see a larger circle through your telescope.
9. There are several impact craters on the surface of Venus.
While the surfaces of Mercury, Mars and the Moon are littered with impact craters, there are relatively few craters on the surface of Venus. Experts believe that the surface of Venus is only five hundred million years old. Permanent volcanism changes the surface, regularly covering any impact craters.
