Solar Cycle 25Approx Read Time: 4 min
- Scientists from NASA have announced their predictions about the new solar cycle, called Solar Cycle 25, which they believe has begun.
- The Solar Cycle 25 Prediction Panel, an international group of experts co-sponsored by NASA, announced that solar minimum occurred in December 2019, marking the start of a new solar cycle.
- Because our Sun is so variable, it can take months after the fact to declare this event.
- Scientists use sunspots to track solar cycle progress.
- With solar minimum having already occured at the end of 2019, scientists expect the Sun’s activity to ramp up toward the next predicted solar maximum in July 2025.
About: Solar cycle
- The Sun’s magnetic field goes through a cycle approximately every 11 years, called the solar cycle.
- After about every 11 years, at the end of a solar cycle, the Sun’s magnetic field completely flips. This means that the Sun’s north and south poles switch places.
- The amount of solar activity changes with the stages in the solar cycle, and this means the number of Sunspots increases and decreases.
- The beginning of a solar cycle is a solar minimum, or when the Sun has the least sunspots. Over time, solar activity—and the number of sunspots—increases.
- The middle of the solar cycle is the solar maximum, or when the Sun has the most sunspots. As the cycle ends, it fades back to the solar minimum and then a new cycle begins.
- Solar activity can have effects here on Earth, so scientists closely monitor solar activity every day. One way to track the solar cycle is by counting the number of sunspots.
About: Sunspots and Solar flares
About: Sun’s surface
- The surface of the Sun is a very busy place.
- It has electrically charged gases that generate areas of powerful magnetic forces called magnetic fields.
- The Sun’s gases are constantly moving, which stretches and twists the magnetic fields. This motion creates a lot of activity on the Sun’s surface, called solar activity
- A solar wind composed of charged particles carries the magnetic field away from the sun’s surface and through the solar system.
- The sun’s magnetic influence extends well past the planets and into interstellar space. This region, called the heliosphere, acts as a magnetic shield against charged particles from deep space called cosmic rays.
- Sunspots are areas that appear dark on the surface of the Sun. Some of these spots are as large as 50,000 km in diameter.
- These spots are the visible markers of the Sun’s magnetic field, which forms a blanket that protects the solar system from harmful cosmic radiation.
- On the photosphere, Sunspots are the areas where the star’s magnetic field is the strongest; around 2,500 times more than the Earth’s magnetic field.
- Photosphere is the outer surface of the Sun which radiates heat and light.
- Sunspots are associated with solar activity, often as the origins for giant explosions – such as solar flares or coronal mass ejections – which can spew light, energy, and solar material into space.
Why Sunspots appear dark:
- They appear dark because they are cooler than other parts of the Sun’s surface.
- It’s because they form at areas where magnetic fields are particularly strong. These magnetic fields are so strong that they keep some of the heat within the Sun from reaching the surface.
- Due to this, the temperatures of Sunspots are thousands of degrees lower than the surrounding photosphere (which has a temperature of 5,800 degrees Kelvin). Sunspots temperatures are around 3,800 degrees Kelvin.
- They typically consist of a dark region called the ‘umbra’, which is surrounded by a lighter region called the ‘penumbra’.
About: Solar flares
- The magnetic field lines near Sunspots often tangle, cross, and reorganize. This can cause a sudden explosion of energy called a solar flare.
- Solar flares release a lot of radiation into space.
- In August 2020, a massive Sunspot group, AR2770, which emitted a few minor solar flares, was observed.
- Coronal Mass Ejections:
- At times, solar flares are accompanied by Coronal Mass Ejections (CME).
- CMEs are huge bubbles of radiation and particles from the Sun. They explode into space at very high speed when the Sun’s magnetic field lines suddenly reorganize.
Importance of studying Solar activity:
- If a solar flare is very intense, the radiation it releases can interfere with our radio communications here on Earth, and impact satellites.
- When charged particles from a Coronal Mass Ejection (CME) reach areas near Earth, they can trigger intense lights in the sky, called auroras.
- When particularly strong, a CME can also interfere in power utility grids, which at their worst can cause electricity shortages and power outages.
- Forecasting of the solar cycle can help scientists protect our radio communications on Earth, and help keep satellites and astronauts safe, too.
- Surveying the space environment is the first step to understanding and mitigating astronaut exposure to space radiation.