Does Venus have a Magnetosphere ?

Mar 5, 2021
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Planets which generate magnetic-fields in their interiors ,such as Earth ,Mercury ,Jupiter and Saturn ,are surrounded by invisible magnetospheres.Their magnetic fields deflect the charged particles of the solar wind (electrons and protons)as they stream away from the sun.This deflection creates Magnetosphere - a protective "bubble" around the planet - which ends in an elongated magnetotail on the lee side of the magnetosphere.

Since Venus has no intrinsic magnetic field to act as a shield against incoming charged particles ,the solar wind sometimes interacts directly with the upper atmosphere, However Venus is partially protected by an induced magnetic field .

As on earth ,solar ultraviolet radiation removes electrons from the atoms and molecules in the upper atmosphere ,creating a region of electrically charged gas known as the Ionosphere .This ionised layer interacts with the solar wind and the magnetic field carried by the solar wind .

During the continuous battle with the solar wind ,this region of the upper atmosphere is able to slowdown and divert the flow of particles around the planet creating a magnetosphere ,shaped rather like a comets tail ,on the lee side of the planet .

Spacecraft observations over many decades have shown that magnetic reconnection occurs frequently in the magnetospheres of Earth ,Mercury ,Jupiter and Saturn.This process which converts magnetic energy into kinetic energy occurs when oppositely directed magnetic field lines break and reconnect. with each other .On earth the reconnection is responsible for magnetic storms and polar auroras- the so called the northern and southern lights .

Until now ,reconnection was not generally thought to occur on non-magnetised planets.However first evidence of magnetic reconnection in Venus magnetotail has been found .

ESA's Venus Express Spacecraft follows a near polar orbit which is ideal to observe the Solar Wind - Ionosphere - Magnetotail interaction .On 15th May 2006 ,Venus Express was crossing the Venusian Magnetotail when it observed a rotational magnetic field structure over a period of about 3 minutes .Calculations based on the duration of observation and the speed of the spacecraft it implied that the magnetic field was 3400 km across. The event was an evidence of a transient magnetic loop structure which is formed by magnetic reconnection in a planetary magnetotail.

Further studies of the magnetic field data from Venus Express revealed the signatures of many similar observations of energy exchange between the magnetic field and the plasma in the tail.

The data also shows that ,in many respect s,the magnetosphere of venus is a scaled down version of Earth's.

The reconnection splits the magnetotail causing most of the plasms in the tail to be ejected into space.The discovery that plasma is lost from the tail as aresult of magnetic reconnections provides a possible new mechanism for explaining how and why gasses are lost from Venus's Upper Atmosphere .This has implications for understanding how Venus lost its water after the planet began to experience a runaway green house effect.
 
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rod

Oct 22, 2019
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Interesting. This 2017 report suggest Venus has no magnetic field or magnetosphere. 'Why doesn't Venus have a magnetosphere?', https://phys.org/news/2017-12-doesnt-venus-magnetosphere.html

"Basically, the energy of this impact would have shaken up the core, creating a single homogeneous region within which a long-lasting geodynamo could operate. Given the age of Earth's magnetic field, this is consistent with the Theia impact theory, where a Mars-sized object is believed to have collided with Earth 4.51 billion years ago and led to the formation of the Earth-moon system."

Apparently Venus suffered no such giant impact event early on according to reports like this. Also Venus has dense CO2 atmosphere, Earth has a chiefly N2O2 atmosphere, and Mars has a thin CO2 atmosphere. Interesting issues appear when explaining how the solar system formed and allowed Earth to be habitable, and inhabited.

On the NASA ADS Abstract system, many reports on Venus and magnetic field.
'The Venusian magnetosphere: past, present and future', https://ui.adsabs.harvard.edu/abs/2019EPSC...13.1351C/abstract, September 2019 with published report attached.
 
Rod, I am no expert here, but wasn't Venus' rotation and orbit characteristics put down to a giant impact (with similarity to Uranus)?

"Venus' rotation and orbit are unusual in several ways. Venus is one of just two planets that rotate from east to west. Only Venus and Uranus have this "backwards" rotation." NASA
 
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rod

Oct 22, 2019
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Good question Catastrophe, I do not really know here :) This report I found, https://www.scientificamerican.com/article/why-venus-spins-the-wrong/

Giant impacts appeal to catastrophism in the solar system to explain *origins* today :) The Venus rotation question has been around a long time too, e.g. The four final rotation states of Venus, https://ui.adsabs.harvard.edu/abs/2001Natur.411..767C/abstract, June 2001

The retrograde rotation of the planet Venus: A numerical model, https://ui.adsabs.harvard.edu/abs/1998APS..TSS...C02C/abstract, March 1998. The abstract says "...The nature of Venus' retrograde rotation is not clearly understood, but is believed to include a major impact by a large body early in the evolution of the planet. A numerical solution to the conservation of angular momentum equations is obtained which considers a major impact in two distinct cases with similar results: (i) a large reduction in the angular velocity past zero, and an eventual reversal of the direction of rotation, and (ii) a large net torque producing a flip of the axis of rotation, with an accompanying loss in angular velocity..."

So Cat, some appeal to catastrophism in the solar system to explain Venus rotation observed today :)
 
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Good question Catastrophe, I do not really know here :) This report I found, https://www.scientificamerican.com/article/why-venus-spins-the-wrong/

Giant impacts appeal to catastrophism in the solar system to explain *origins* today :) The Venus rotation question has been around a long time too, e.g. The four final rotation states of Venus, https://ui.adsabs.harvard.edu/abs/2001Natur.411..767C/abstract, June 2001

The retrograde rotation of the planet Venus: A numerical model, https://ui.adsabs.harvard.edu/abs/1998APS..TSS...C02C/abstract, March 1998. The abstract says "...The nature of Venus' retrograde rotation is not clearly understood, but is believed to include a major impact by a large body early in the evolution of the planet. A numerical solution to the conservation of angular momentum equations is obtained which considers a major impact in two distinct cases with similar results: (i) a large reduction in the angular velocity past zero, and an eventual reversal of the direction of rotation, and (ii) a large net torque producing a flip of the axis of rotation, with an accompanying loss in angular velocity..."

So Cat, some appeal to catastrophism in the solar system to explain Venus rotation observed today :)
But is not the impact theory applied to Uranus in a similar circumstance?
Two swallows might not make a summer (old saying) but there are more swallows than planets. Cat :)
 
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rod

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But is not the impact theory applied to Uranus in a similar circumstance?
Two swallows might not make a summer (old saying) but there are more swallows than planets. Cat :)
Yes, Cat apparently the appeal to giant impacts is all the rage :) Co-accretion + giant impact origin of the Uranus system, https://ui.adsabs.harvard.edu/abs/2020DPS....5250701R/abstract, October 2020. "In this study, we are exploring whether a combination of co-accretion and a giant impact could explain the observed properties of the Uranian system (Morbidelli et al. 2012)."

Remember, in the ecliptic today we see about 447 earth masses from Mercury to Pluto or so. In the catastrophism models in use, many thousands or more earth masses of dust and objects, all enjoying impacts and catastrophic events to create you and I, apparently :)
 
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