The sun has been pretty busy the past few weeks. On Tuesday, our star fired off two enormous explosions from its farside in what has already been a heavy month of solar activity.
A magnificent coronal mass ejection (CME) was recorded by Nasa’s STEREO-A spacecraft in the early hours of February 15. CMEs are giant eruptions that send plasma hurtling through space – and the Sun has undergone several of them throughout the month.
If they hit Earth, the plumes of material can trigger geomagnetic storms that knock out satellites and disrupt power grids. Fortunately, this week’s CME was fired from the side of the Sun that faces away from our planet and so poses no threat, says astronomer Dr. Tony Phillips.
Writing on his website spaceweather.com, which tracks the sun’s activity, he said: “This CME will not hit Earth; it is moving away from, not toward our planet. “However, if such a CME did strike, it could produce a very strong geomagnetic storm. We may have dodged a bullet.”
Based on its size, it’s possible that the eruption was an X-class flare: The most powerful category possible. “This is only the second farside active region of this size since September 2017,” astronomer Junwei Zhao of Stanford University’s helioseismology group told SpaceWeather.
“If this region remains huge as it rotates to the Earth-facing side of the Sun, it could give us some exciting flares.” It’s been a busy month of solar activity. The Sun has erupted every day for the month of February, according to Dr Phillips. Some days have seen multiple solar flares. Three of them have fallen into the second-most powerful flare category, M-class flares. January saw five M-class flares.
One such flare led to a solar storm on January 29 that knocked 40 SpaceX satellites out of action.
The rest of the flares in February have fallen into the milder C-class category.
While it might sound frightening, it’s all part of our Sun’s normal activity – so there’s no need to panic just yet.
Astronomers keep a close eye on the Sun’s activity to ensure that there is plenty of warning before any potential geomagnetic storm hits.
What are geomagnetic storms?
Geomagnetic storms are caused by CMEs, which are huge expulsions of hot material called plasma from the Sun’s outer layer.
They can lead to the appearance of colourful auroras by energising particles in our planet’s atmosphere
Each solar storm is graded by severity on a scale of one to five, with a G1 described as “minor” and a G5 as “extreme”.
At the upper end of the scale, storms wreak havoc on our planet’s magnetic field, which can disrupt power grids and communications networks.
“Harmful radiation from a flare cannot pass through Earth’s atmosphere to physically affect humans on the ground,” Nasa says.
“However – when intense enough – they can disturb the atmosphere in the layer where GPS and communications signals travel.”
When have major geomagnetic storms hit Earth?
In the past, larger solar flares have wreaked havoc on our planet.
In 1989, a strong solar eruption shot so many electrically charged particles at Earth that the Canadian Province of Quebec lost power for nine hours.
As well as causing issues for our tech, they can cause harm to astronauts working on the International Space Station, either through radiation exposure or by interfering with mission control communications.
The Earth’s magnetic field helps to protect us from the more extreme consequences of solar flares.
Weaker solar flares – which are far more common – are responsible for auroras such as the Northern Lights.
Those natural light displays are examples of the Earth’s magnetosphere getting bombarded by solar wind, which creates the bright green and blue displays.
The sun is currently at the start of a new 11-year solar cycle, which usually sees eruptions and flares grow more intense and extreme.
These events are expected to peak around 2025 and it’s hoped the Solar Orbiter will observe them all as it aims to fly within 26 million miles of the sun.