AR3664 is no ordinary sunspot.
A huge dark spot on the surface of the Sun has grown in size in recent days, becoming one of the largest and most active sun spots saw this solar cycle.
AR3664 caught the attention of scientists earlier this week when the National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center issued a warning on Tuesday (May 7) about an increased risk of a solar flare from the solar giant.
“Region 3664 has grown considerably and become much more magnetically complex,” NOAA’s SWPC report. “This has led to an increased likelihood of a solar flare over the next few days.”
The giant sunspot more than lived up to expectations. Firing countless powerful solar flares in recent days, including a colossal X-class solar flare this morning (May 9), which peaked at 5:13 a.m. EDT (0913 GMT).
Related: Sun explodes in burst of powerful solar flares from hyperactive sunspots (video)
Solar flares are eruptions from the sun’s surface that emit intense bursts of electromagnetic radiation. They are categorized by size into groups marked with letters, and the X-class is the strongest. Then there are M-class flares, which are 10 times less powerful than X-class flares, then C-class flares, which are 10 times weaker than M-class flares, B-class flares, which are 10 times weaker than C-class flares, and finally, A-class flares, which are 10 times weaker than B class flares and they have without visible consequences on Earth. Within each class, numbers from 1-10 (and higher for Class X flares) describe the relative power of the flare.
The X-flare was X 2.25 this morning according to spaceweatherlive.com, as measured by NASA’s GOES-16 satellite.
Disappearance of the radio
Powerful solar flares like the one observed this morning can cause shortwave radio to go out on the sunlit side Earth at the time of the eruption. As such, the X-flare caused a shortwave radio blackout across Europe and Africa this morning as seen in the image above.
The radio blackouts are caused by the powerful X-ray pulse and extreme ultraviolet radiation emitted during the eruption.
The radiation travels towards the Earth at speed of light and ionizes (gives an electrical charge to) the tip Earth’s atmosphere. (Note: These ionizing X-rays are not to be confused with coronal mass ejection (CMEs) from which plasma and magnetic fields emerge Suntraveling at slower speeds, it often takes several days to reach Earth).
This ionization causes a higher density environment through which high-frequency short-wave radio signals pass to support long-distance communication. Radio waves that interact with electrons in the ionized layers, they lose energy due to more frequent collisions, and this can lead to degradation or complete absorption of the radio signal according to NOAA’s Space Weather Prediction Center.
Sunspot visible from Earth
Stretching nearly 124,000 (200,000 kilometers) from end to end, sunspot AR3664 is currently 15 times wider than our planet, according to Spaceweather.com.
It is so large that it can be seen from Earth without the need for magnification. If you still have a pair solar eclipse glasses lying around after the total solar eclipse on April 8, you can use them to safely observe the sun and watch the huge sunspot cross the solar disk.
But remember NEVER look at the sun without proper sun protection. With our help, you can learn how to observe the sun safely a guide to observing the sun.
A rival to Carrington’s sunspot
The sheer size of Sunspot AR3664 rivals Carrington’s 1859 sunspot, as shown in this image from Spaceweather.com. The Carrington Sunspot is famous for its explosive rampage between August and September 1859, during which it triggered a series of powerful solar flares and CMEs, resulting in large geomagnetic storms that set fire to telegraph offices and set off polar lights near the equator like Cuba and Hawaii.
Read more: The Carrington event: the largest solar storm in history
Although studies suggest With Carrington-class solar storms occurring every 40 to 60 years or so (and we’re long overdue), there’s no evidence that any CME currently en route from previous solar eruptions this week could cause another Carrington event, according to Spaceweather.com.
Scientists are keeping a close eye on this ever-growing sunspot as it continues to face Earth.