# How much time would take for Venus to generate a Magnetic Field?

Supposing that we managed to speed up Venus's rotation to a 24 hour cycle in just under 40 years (how we managed to do that is irrelevant here), how much time would take for Venus to form a magnetic field?

Considering that the existence of a magnetic field is related (but not exclusive) to a planet's rotational period, what is the timescale we could be seeing? 100 years? 1000? A million?

Edit: I replaced 'magnetosphere' to 'magnetic field' as JBH recommended below.

• /Considering that the existence of a magnetosphere is related to a planet's rotational period/ - that is news to me. Can you link a reference about that relationship? Dec 11, 2022 at 22:04
• Why would there be any relationship between the rotation period of a planet and the presence or absence of a magnetosphere? (For example, Mars has about the same rotation period as Earth; Earth has a magentosphere, Mars doesn't.) And why do you care about Venus having a magnetosphere? Dec 11, 2022 at 22:11
• Why you want a magnetosphere is unimportant. How magnetospheres form is important. First, there's a difference between a planet's magnetic field and the magnetosphere, which is caused by the interraction of the solar wind with a planet's magnetic field. So what you're really asking is how to create a magnetic field. "Planetary magnetic fields are formed by the interaction between the convection of interior conducting material (molten rock and metal) and the planet's own rotation. Mercury's field is weak because... (*Continued*)
– JBH
Dec 12, 2022 at 1:45
• ... it rotates so slowly." (Source) So you are correct that rotational speed is involved, but it's not the only variable. If a planet is formed completely of rock, all the spinning in the universe won't create a magnetic field. There must also be metal. Good for you Q, Venus has an iron-nickel core. So, spin it up fast enough and you might get a magnetic field. Therefore, it's my opinion that this Q is reasonable. (*Continued*)
– JBH
Dec 12, 2022 at 1:47
• ... However, it would help a lot if you edit your question and replace "magnetosphere" with "magnetic field" to avoid the inevitable confusion.
– JBH
Dec 12, 2022 at 1:48