Solar wind enveloped Earth, claims NOAA. Here’s what has happened so far

As per the National Oceanic and Atmospheric Administration (NOAA), a dense stream of solar wind enveloped the Earth late on 14 July, but no notable impact was observed as the phenomenon wasn't particularly powerful on the space weather scale.

The American agency confirmed that the phenomenon lasted for a few hours and slightly unsettled the Earth's magnetic field.

The solar storm passed through the planet at 16:41 UTC (22:11 IST) with a geomagnetic K-index of 4. The K-index is used to characterise the magnitude of geomagnetic storms, and a level of 4 indicates minor disturbance, as per the NOAA alert.

The US agency stated that weak power grid fluctuations happened due to the solar storm, and expected auroras to be visible at high latitudes such as Canada and Alaska. However, the local US media has not reported any such sightings.

All about the solar storm

The massive solar storm, which moved towards the Earth at a speed of 1.6 million kilometres per hour, was supposed to hit the Earth last week, following which a power failure around the globe was expected, according to spaceweather.com.

"THE SOLAR WIND IS COMING: Later today, a high-speed stream of solar wind is expected to hit Earth's magnetic field. Flowing from an equatorial hole in the sun's atmosphere, wind speeds could top 500 km/s. Full-fledged geomagnetic storms are unlikely, but lesser geomagnetic unrest could spark high latitude auroras," the spaceweather.com said.

The National Oceanic and Atmospheric Administration has reportedly classified the solar storm as G-1 or 'minor'.

What are geomagnetic storms?

A major disturbance of Earth's magnetosphere, which occurs when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth, is known as a geomagnetic storm. The storm is the result of major changes in the currents, plasmas produced by solar winds, as per the NOAA.

The most powerful geomagnetic storm ever recorded resulted in the 1859 Carrington Event, when telegraph lines electrified, zapping operators and setting offices ablaze in North America and Europe.

To create a geomagnetic storm, a solar wind has to sustain high speeds for a long period of time, which transfers the energy of the wind into Earth's magnetic field.

The fierce and largest storms that result from these situations are associated with solar Coronal Mass Ejections (CMEs) where billions of tons of plasma from the Sun are hurtled towards planets that also reach Earth. While coronal mass ejections take days to arrive at Earth, some have been observed to arrive within 15-18 hours of being ejected from the Sun.