Why venus and uranus rotate from east to west?
Why venus and uranus rotate from east to west?
You're undoubtedly thinking of Venus as the planet that spins east to west. In other words, if you arrived on Venus in the morning, the sun would be in the west and would set in the east. The only thing is that it would set about four Earth-months later! That's because a day on Venus lasts for 243 of our Earth-days.
Actually, you should probably add Uranus to your list of planets in retrograde (or "backward") rotation, because it is tipped more than 90 degrees. The day would be a short one, because Uranus completes a rotation on its axis every 17 hours, which is a pretty typical time for all the gas giants. The Uranian year is 84 Earth years. Over that time there are large seasonal variations at the poles as they alternately point toward and away from the sun.
As a rule, the inner planets (the solid ones) have much longer spin periods. Mercury completes three rotations every time it goes around the sun once because it is in a tidal lock with the sun, in a manner similar to the tidal lock that causes the moon to always face Earth. A day there lasts about 30 Earth-days.
Mars has the same spin period as Earth, but the angle between its spin axis and the axis of its orbital angular momentum is predicted to vary chaotically between about 11 and 44 degrees on a time scale of millions of years. This is due to the gravity of the sun and other planets. So if you go to Mars now, the sun would rise in the east southeast if you landed at a Southern California latitude during the summer. But if you wait a few million years, the planet might be so tilted that the sun would come up a few degrees north of east each morning while you were at that same latitude at the same time of year.
To get back to your question, nobody knows why the planets have the spins they have. It's plausible that the spin rates date back to the formation stage of the solar system, which began about 4.6 billion years ago and lasted about half a billion years. Because fairly big bodies were being gobbled up by the planets that we observe today, the inclinations of the axes as well as the spin rates are probably relics of these collisions.
Probably, both Venus and Uranus originally rotated from west to east, just like the other seven planets. Perhaps the collisions of other bodies with these two planets flipped them over permanently. In the case of Venus, the tidal effect of the ;sun's gravity also undoubtedly had a profound effect.
An article I liked:-
Let’s take ourselves traveling into the past. Well not literally going to the past, but let’s explore the time when all the planets formed. At that time, all the planets rotated in the same direction. But something came along that changed the rotational direction of Venus and Uranus.
Lets start with Venus. There are a few possibilities that we can take into account to explain why Venus rotates backwards. Venus is initially rotating counterclockwise like the other planets and it still does. In other words, it spins in the same direction it always has, just upside down, so that looking at it from the other planets makes the spin look backward. As I said before, there are a few explanations for this.
Scientists have argued that the sun’s gravitational pull on the planet’s very dense atmosphere could have caused strong atmospheric tides. Such strong tides could have caused the flip to happen.
Another explanation comes from the cratering evidence on each planet. Soon after the planets were formed, there still were many large and small objects or maybe we can classify them as mini planets that orbited the Sun. So.. this interaction with all the planets eventually cleared each planet’s orbit as we know now. This is what happened to the Earth/Moon system when a Mars-sized body collided with the Earth and the leftover material merged and formed the Moon.
And Venus may have experienced an encounter with one of these larger bodies in a gigantic impact in which, unlike the Earth, the extra material didn’t form a separate moon, but stopped and even reversed its rotation altogether.
Another simulation was made by Alex Alemi and David Stevenson from California Institute of Technology, to trace the oddness of Venus’s orbit. They proposed 2 large impacts in Venus’s history. The first impact’s result was a satellite for Venus but after 10 million years Venus encountered another gigantic impact on the opposite side of the planet from the first impact which reversed its rotation and the satellite it once had spiralled in and collided with the planet itself.
That’s Venus. As for Uranus, it’s quite unique since it’s not rotating in the regular clockwise or counterclockwise direction. Well if Venus was rotating upside down then.. someone must have kicked this planet and made it roll on its side. Most planetary axes are perpendicular to the orbital plane. But Uranus’s axis is extremely tilted to 97.7º and its pole is pointed toward the equatorial plane of the other planets.
This extreme tilt leads to the radical seasons that the planet experiences and makes the planet have unusual days at the poles. At the equator, Uranus experiences normal days and nights. But because it rotates on its side, at any given time one pole or the other is pointed more or less towards the Sun. This results in one pole experiencing 42 Earth years of day followed by 42 years of night. When the North Pole is toward the Sun, the South Pole is in darkness and vice-versa.
So how could this have happened? Same as with Venus, Uranus also had counterclockwise rotation until a gigantic impact changed everything. The explanation for this is that in its formation history, Uranus collided with an Earth-sized object which lead to the change of its rotation.
Another theory and simulation without collision by Gwenael Boue and Jacques Laskar from Paris Observatory shows that Uranus had very large moon with 0,1 % of Uranus’s mass. The gravitational interaction between the two changed Uranus’s axis to tilt the way it is now. And for the moon itself, it was ejected from the system when they encountered other massive planets.
You're undoubtedly thinking of Venus as the planet that spins east to west. In other words, if you arrived on Venus in the morning, the sun would be in the west and would set in the east. The only thing is that it would set about four Earth-months later! That's because a day on Venus lasts for 243 of our Earth-days.
Actually, you should probably add Uranus to your list of planets in retrograde (or "backward") rotation, because it is tipped more than 90 degrees. The day would be a short one, because Uranus completes a rotation on its axis every 17 hours, which is a pretty typical time for all the gas giants. The Uranian year is 84 Earth years. Over that time there are large seasonal variations at the poles as they alternately point toward and away from the sun.
As a rule, the inner planets (the solid ones) have much longer spin periods. Mercury completes three rotations every time it goes around the sun once because it is in a tidal lock with the sun, in a manner similar to the tidal lock that causes the moon to always face Earth. A day there lasts about 30 Earth-days.
Mars has the same spin period as Earth, but the angle between its spin axis and the axis of its orbital angular momentum is predicted to vary chaotically between about 11 and 44 degrees on a time scale of millions of years. This is due to the gravity of the sun and other planets. So if you go to Mars now, the sun would rise in the east southeast if you landed at a Southern California latitude during the summer. But if you wait a few million years, the planet might be so tilted that the sun would come up a few degrees north of east each morning while you were at that same latitude at the same time of year.
To get back to your question, nobody knows why the planets have the spins they have. It's plausible that the spin rates date back to the formation stage of the solar system, which began about 4.6 billion years ago and lasted about half a billion years. Because fairly big bodies were being gobbled up by the planets that we observe today, the inclinations of the axes as well as the spin rates are probably relics of these collisions.
Probably, both Venus and Uranus originally rotated from west to east, just like the other seven planets. Perhaps the collisions of other bodies with these two planets flipped them over permanently. In the case of Venus, the tidal effect of the ;sun's gravity also undoubtedly had a profound effect.
An article I liked:-
Let’s take ourselves traveling into the past. Well not literally going to the past, but let’s explore the time when all the planets formed. At that time, all the planets rotated in the same direction. But something came along that changed the rotational direction of Venus and Uranus.
Lets start with Venus. There are a few possibilities that we can take into account to explain why Venus rotates backwards. Venus is initially rotating counterclockwise like the other planets and it still does. In other words, it spins in the same direction it always has, just upside down, so that looking at it from the other planets makes the spin look backward. As I said before, there are a few explanations for this.
Scientists have argued that the sun’s gravitational pull on the planet’s very dense atmosphere could have caused strong atmospheric tides. Such strong tides could have caused the flip to happen.
Another explanation comes from the cratering evidence on each planet. Soon after the planets were formed, there still were many large and small objects or maybe we can classify them as mini planets that orbited the Sun. So.. this interaction with all the planets eventually cleared each planet’s orbit as we know now. This is what happened to the Earth/Moon system when a Mars-sized body collided with the Earth and the leftover material merged and formed the Moon.
And Venus may have experienced an encounter with one of these larger bodies in a gigantic impact in which, unlike the Earth, the extra material didn’t form a separate moon, but stopped and even reversed its rotation altogether.
Another simulation was made by Alex Alemi and David Stevenson from California Institute of Technology, to trace the oddness of Venus’s orbit. They proposed 2 large impacts in Venus’s history. The first impact’s result was a satellite for Venus but after 10 million years Venus encountered another gigantic impact on the opposite side of the planet from the first impact which reversed its rotation and the satellite it once had spiralled in and collided with the planet itself.
That’s Venus. As for Uranus, it’s quite unique since it’s not rotating in the regular clockwise or counterclockwise direction. Well if Venus was rotating upside down then.. someone must have kicked this planet and made it roll on its side. Most planetary axes are perpendicular to the orbital plane. But Uranus’s axis is extremely tilted to 97.7º and its pole is pointed toward the equatorial plane of the other planets.
This extreme tilt leads to the radical seasons that the planet experiences and makes the planet have unusual days at the poles. At the equator, Uranus experiences normal days and nights. But because it rotates on its side, at any given time one pole or the other is pointed more or less towards the Sun. This results in one pole experiencing 42 Earth years of day followed by 42 years of night. When the North Pole is toward the Sun, the South Pole is in darkness and vice-versa.
So how could this have happened? Same as with Venus, Uranus also had counterclockwise rotation until a gigantic impact changed everything. The explanation for this is that in its formation history, Uranus collided with an Earth-sized object which lead to the change of its rotation.
Another theory and simulation without collision by Gwenael Boue and Jacques Laskar from Paris Observatory shows that Uranus had very large moon with 0,1 % of Uranus’s mass. The gravitational interaction between the two changed Uranus’s axis to tilt the way it is now. And for the moon itself, it was ejected from the system when they encountered other massive planets.
