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Auroras will be visible further south this year as the solar storm cycle peaks

An important discovery in the study of the Sun’s behavior was released today by researchers at the Center of Excellence in Space Sciences India (CESSI). Their work has unveiled a new relationship between the Sun’s magnetic field, solar flares, and the sunspot cycle. This discovery holds significant promise for predicting solar activities with greater accuracy.

Sun’s magnetic field and sunspot cycle

The Sun, our nearest star, is a massive sphere of hot ionized gas, or plasma. Within it, immense plasma flows and convection currents interact to form magnetic fields. These fields surface as sunspots, dark patches comparable in size to Earth. These sunspots are centers of intense magnetism, possessing a magnetic strength about 10,000 times greater than Earth’s.

Occasionally, these sunspot magnetic fields undergo violent disruptions, giving rise to solar magnetic storms such as flares and coronal mass ejections. These phenomena emit high-energy radiation and expel vast amounts of magnetized plasma into space. The most intense of these storms can wreak havoc on satellites, power grids, and communication networks on Earth.

Challenge of predicting solar flares

Sunspot observation, dating back to the early 1600s, reveals a cyclic pattern. Approximately every 11 years, the number of sunspots and the intensity of solar activity peak, leading to heightened space weather disturbances. However, accurately predicting these peaks has been a longstanding challenge.

A dynamo mechanism, powered by plasma flows inside the Sun, drives the solar cycle. This mechanism involves two primary magnetic field components.

One component manifests in sunspots. The other component is active in recycling the Sun’s large-scale dipole field, similar to Earth’s magnetic field. Every 11 years, this dipole field also reverses its poles.

Expanding on Waldmeier’s discovery

In 1935, Swiss astronomer Max Waldmeier discovered a relationship known as the Waldmeier effect. Waldmeier found that the faster a sunspot cycle rises, the stronger the strength of the solar storms. This relationship has been pivotal in forecasting the strength of sunspot cycles based on early observations.

Priyansh Jaswal, Chitradeep Saha, and Dibyendu Nandy of IISER Kolkata have discovered a complementary relationship. They found that the rate of decrease in the Sun’s dipole magnetic field correlates with the rate of rise of the ongoing sunspot cycle.

This discovery, leveraging data from decades-old solar observatories, connects the two primary components of the Sun’s magnetic field. In addition, it supports the notion that sunspots are integral to the solar dynamo process.

Predictions for the current solar cycle

The IISER Kolkata team demonstrates how monitoring the Sun’s dipole magnetic field’s rate of decrease, combined with sunspot observations, can predict the peak of an ongoing cycle. Their analysis suggests that the peak of solar cycle 25 is likely to occur in early 2024, with a range of uncertainty extending to September 2024.

In summary, this new discovery opens a window for more accurate forecasting of solar cycle peaks. These are times when the most intense solar activity and space weather disturbances are expected. Such advancements in understanding the Sun’s magnetic dynamics are not only pivotal for space weather prediction but also essential for protecting Earth’s technological infrastructure.

More about the solar flares

As discussed above, solar storms and solar flares are powerful eruptions of electromagnetic energy and matter from the Sun. They significantly influence the solar system, particularly impacting Earth’s magnetic field and atmosphere. Let’s dig a little deeper.

Types of solar storms

The Sun’s magnetic field drives solar storms. Complex magnetic field interactions, often occurring near sunspots, lead to a sudden release of energy, causing these different types.

Solar Flares — Intense bursts of radiation, are the Sun’s most common type of solar storm. They emanate from the release of magnetic energy stored in the Sun’s atmosphere and can last from minutes to hours.

Coronal Mass Ejections (CMEs) — Massive bursts of solar wind and magnetic fields rising above the solar corona or being released into space. CMEs can eject billions of tons of coronal material and carry an embedded magnetic field stronger than the background solar wind interplanetary magnetic field (IMF).

Solar Proton Events — These involve large quantities of high-energy protons released by the Sun. These particles can reach Earth within minutes to hours of a major solar flare, posing a risk to astronauts and satellites.

Impact of solar storms on Earth

Solar storms can disrupt satellite operations, communications signals, and navigation systems. They can induce electrical currents in power lines, leading to power outages.

The interaction of solar storm particles with Earth’s magnetic field and atmosphere creates spectacular light shows known as auroras, predominantly visible near the polar regions.

In summary, solar storms are dynamic and powerful expressions of the Sun’s energy. Understanding them is crucial for protecting Earth’s technological infrastructure and furthering our knowledge of solar-terrestrial interactions.

More about auroras

Auroras, often called Northern or Southern Lights depending on their location, present one of nature’s most spectacular displays. They occur when charged particles from the sun collide with Earth’s magnetic field. This interaction energizes particles in Earth’s atmosphere, causing them to light up and create the beautiful colors typical of auroras.

How an aurora is made

The process begins with the sun emitting a stream of charged particles, known as the solar wind. As these particles approach Earth, they interact with the magnetic field that surrounds our planet. This magnetic field extends far into space and acts as a protective shield, deflecting many of the solar particles.

However, near the polar regions, the Earth’s magnetic field lines converge and guide these charged particles into the upper atmosphere. Here, they collide with oxygen and nitrogen atoms. These collisions excite the atoms, elevating electrons to higher energy levels. When these electrons return to their original energy levels, they release photons, small packets of light, which we see as the aurora.

Colors and viewing

The colors of the aurora depend on the type of gas molecules involved and the altitude of the interaction. Oxygen, at about 60 miles up, emits a green or red light, while nitrogen typically produces blue or purple hues. The intensity of these lights can vary, from subtle glows to rapidly moving curtains of light that cover the sky.

Auroras are best observed during the equinoxes due to the alignment of Earth’s magnetic field with the solar wind. However, they can occur at any time and are more frequently seen in polar regions due to the structure of Earth’s magnetic field.

While auroras are a natural phenomenon, they can also indicate changes in solar activity, which can have impacts on satellite communications and power grids. Scientists closely monitor auroras to understand better the complex interactions between the sun and Earth’s magnetic field.

In summary, auroras are a breathtaking natural phenomenon resulting from the interaction of solar particles with Earth’s magnetic field and atmosphere, creating stunning light displays in the night sky.

The full study was published in Monthly Notices of the Royal Astronomical Society: Letters

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