One of the defining characteristics of the Earth is its magnetic field. It creates a protective shield against high-energy particles thrown by. Sun and thus it could be argued that it provided a safer place for life to develop into the complex array of organisms we see today.
The most striking symptoms Earth’s magnetic field like that aurorasDancing curtains of colored light that appear near the North and South poles during times of high solar activity. Another sign of this Soil The thing about having a magnetic field is that the compass points north no matter where you are on the planet.
So how can we understand whether other planets or objects in the solar system have a magnetic field? And is it possible to know whether it is far or not? outer planets Are there magnetic fields?
Relating to: Why are Earth’s magnetic poles changing?
Gas giants of the solar system (Jupiter And Saturn) and ice giants (Uranus And Neptune) have strong internal magnetic fields. However, this situation is a little more complicated terrestrial planets months, according to planetary scientist Joseph G. O’Rourke of Arizona State University.
Soil, Mercury and Jupiter’s moon in the booty today they all have internally generated magnetic fields. Anthem And earth’s moon They have ancient crustal rocks that preserve remnants of magnetization from magnetic fields that existed early in their history, O’Rourke said.
As for Earth’s other neighbor: “No intrinsic magnetism has been detected on Earth. Venus“But we didn’t send instruments close enough to the surface to look for the magnetized shell,” he added.
For a magnetic field to exist on a planet or moon, a large amount of conductive fluid must be in motion within that body. If the movement of these materials is stopped, or if there is not enough temperature difference between heating and cooling of the materials to stimulate convection of fluids inside a planet or moon, the body may lose its magnetic field; In this case, the fluids would move very slowly, O’Rourke said.
According to O’Rourke, there are four possibilities in the apparent absence of a magnetosphere on Venus.
The generally accepted idea is that Venus has an Earth-like core that cools very slowly. Because Venus does not have plate tectonics, its interior may be cooling more slowly than Earth’s.
However, an alternative possibility is that the interior of Venus is completely solid. This would require the planet’s core to be much colder than Earth’s, which O’Rourke thinks is unlikely. NASA’s Venus Emission, Radio Science, InSAR, Topography and Spectroscopy mission is planned for 2031, and the European Space Agency’s EnVision mission will try to understand whether the core of Venus is at least partially liquid.
Alternatively, Venus may not have an inner core. Earth’s inner core helps create our planet’s magnetic field. As it crystallizes, it expels impurities (elements lighter than iron), creating chemical buoyancy that drives fluid movements. Perhaps Venus has not yet formed an inner core, so it lacks the extra power source.
A fourth possibility is that Venus’s core may be chemically stratified, O’Rourke said. The moon-forming impact may have excited the ancient Earth’s core, causing it to create a magnetic field as it cooled. But Venus has no moons, which could mean nothing is cluttering its core.
The best way to determine whether objects in the solar system have a magnetic field is to have a spacecraft go to the object to measure the intensity of the magnetic field with a magnetometer. However, scientists were able to detect it remotely Jupiter’s magnetic field in the 1950s by collecting radio emissions from the planet’s auroras.
Magnetic fields are one of the best ways to learn about the interiors of planets, O’Rourke said. The presence of a strong magnetic field tells scientists that the planet has a large reservoir of electrically conductive liquid that can move around.
“A dynamo is the process by which the energy of fluid motion is converted into a magnetic field,” O’Rouke explained. “On terrestrial planets, metallic cores can host dynamos, as on Earth today. However, liquid silicates (basically molten rocks) are electrically conductive at extreme pressures and temperatures. Hydrogen becomes metallic deep inside gas giants such as Jupiter and Saturn “This makes their strong magnetic fields possible.”
Do any exoplanets have a magnetic field?
When it comes to exoplanets, which are planets outside the solar system Planetary scientists have yet to definitively detect the existence of a magnetic field. But O’Rourke thinks we’re not that far off. Astronomers have detected auroras caused by magnetic fields on small stars. brown dwarfs and low-mass M dwarfs.
“I predict that the next generation of instruments will be able to detect magnetic fields from Jupiter-like exoplanets,” O’Rourke said. “The detection of magnetic fields from Earth-like planets is on a more distant horizon, but we hope that it will be possible within the next few decades. In general, we can detect the magnetic fields of exoplanets either directly (for example, by observing auroras or radiation belts) or indirectly (for example, by observing auroras or radiation belts). , by observing the interactions of planetary magnetic fields with host stars).”
Planetary scientists are currently debating whether magnetic fields generally maintain planetary atmospheres. On the one hand, magnetic fields can protect atmospheres, especially near the magnetic equator, from stellar winds. O’Rourke explained that, on the other hand, magnetic fields can direct charged particles to the polar regions, and some mechanisms that contribute to atmospheric escape are not strongly affected by magnetic fields.
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“Earth has maintained both a magnetic field and a habitable surface for billions of years,” O’Rourke said. said. “Mars lost roughly most of its water to space when its magnetic field died. There is no magnetic field on the netherworld Venus. In our solar system, magnetism correlates with habitability. But correlation is not causation.”
As we reach a larger sample size of exoplanets through observations James Webb Space Telescope, planetary scientists will begin to uncover the relationship between magnetic fields and planet habitability. Auroras may be one of the first indicators that we need to look a little closer at signs of life.