Powerful ‘X-class’ solar flare from rapidly growing sunspot triggers radio blackout in US

Flares lead to brief radio blackouts for about 30 minutes in western US

A powerful solar flare from a fast-growing sunspot on the Sun’s surface triggered radio blackouts in some parts of the US.

The giant sunspot, named AR3354, was first spotted on the Sun on June 27 and grew rapidly within a span of two days to a size about 10 times larger than Earth, raising concerns among space weather scientists.

This sunspot first produced a minor M-class flare on 29 June and, after a brief period of calm, unleashed an X-class flare – the most powerful category of solar flare the Sun can belch out – aimed directly at Earth.

Solar flares are giant explosions on the Sun’s surface that send out charged particles and energy into space at high speeds. They are categorised as either A, B, C, M or X, with each successive letter representing a 10-fold increase in energy output.

“When this week began, sunspot AR3354 didn’t exist. Now it is 10 times wider than Earth and still growing. The sunspot burst into view on June 27th, breaching the surface of the sun, then blossoming into a giant over the next 48 hours,” noted Spaceweather.com.

The sunspot is so big that amateur astronomers are able to observe it and see details that are normally found by the world’s greatest telescopes.

The US federal body National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center reported a “strong radio blackout” in parts of the US on Sunday.

“The flare came from a large and complex region denoted as sunspot group 3354,” NOAA said, adding that it led to a “temporary degradation or complete loss of High Frequency (HF) radio signals” on some of the sunlit sides of Earth.

Some of the biggest X-class solar flares to hit Earth have led to long-lasting radiation storms, which can potentially harm satellites, communications systems and even power grids.

The solar storm on Sunday led to brief radio blackouts lasting for about 30 minutes in the western US and parts of the eastern Pacific Ocean, according to NOAA.

The flare peaked in intensity at 7.14pm ET on 2 July, Nasa’s Solar Dynamics Observatory said in a statement.

However, experts said if the flare had launched along with it fast-moving charged particles, in what’s called a coronal mass ejection (CME), it might have led to an even larger radio blackout.

The sunspot AR3354 has not yet shrunk in size and may still belch out more solar flares in the coming days.

Flares and CMEs are produced by the snapping and reconnection of the Sun’s magnetic field lines, often at sunspots.

The appearance of more frequent sunspots as well as larger ones is a sign of the Sun nearing Solar Maximum – the most active time of the Sun’s 11-year cycle – experts said.