Space Weather

Space Weather

Space weather describes changing environmental conditions in near-Earth space. Magnetic fields, radiation, particles and matter, which have been ejected from the Sun, can interact with the Earth’s upper atmosphere and surrounding magnetic field to produce a  variety of effects.

Image courtesy of NASA/SDO and the AIA, EVE, and HMI science teams

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Aurora forecasts

Northern Hemisphere

Up to two CMEs feature in the forecast, with both emitted on 16 July and due at Earth very late in the current UTC day or more likely into Saturday 20 July. This may mean that aurorae become visible in parts of (mainly northern) Scotland and similar geomagnetic latitudes into the early hours of Saturday and perhaps again that evening, although this will be limited by the short hours of darkness and the near-full moon. The geomagnetic forecast and chances of aurorae should return to quiet into the new UTC working week.

Southern Hemisphere

Up to two CMEs feature in the forecast, with both emitted on 16 July and due at Earth very late in the current UTC day or more likely into Saturday 20 July. This may mean that aurorae become visible in the extreme south of New Zealand and perhaps Tasmania. The geomagnetic forecast and chances of aurorae should return to quiet into the new UTC working week.

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Forecast overview

Space Weather Forecast Headline: Isolated Moderate class flares expected. Chance of G1 Minor Storms day 1 (20 Jul)

Analysis of Space Weather Activity over past 24 hours

Solar Activity: Moderate with two Moderate class-flares observed. The strongest flare was at 19/0823 UTC from a small region in the northwest, with a further Moderate flare also observed at 19/1825 UTC from the largest of the fifteen sunspot regions currently visible. This is also the most complex sunspot group on the disc, currently located in the south-centre disc. Some simplification of this region has occurred, consolidating into three main, but still small and rather ragged spots. The interior spot, however, maintains some mixed magnetic polarities. Rapid growth was also observed in a newly numbered and emergent spot to the east of this region. While this currently has a relatively simple bipolar structure, any further growth has the potential to destabilise the large spot due to its proximity. The other regions on the disc are generally smaller and either stable or decaying. The only exception is a moderately sized region in the southwest, with some limited growth observed, however this remains a simple bipolar region

A large eruption was observed off the south-centre disc just after 19/1930 UTC, due to a 'filament eruption'. These occur when a line of material, held together but observed the Sun's surface by its magnetic field, becomes unstable and is erupted. A coronal mass ejection (CME) likely occurred and despite it having a likely southward bias, an Earth-directed component is possible. However sufficient imagery is currently not available to assess this.     

Solar Wind / Geomagnetic Activity: The solar wind speed was at background, 300-350 km/s. Density was average or below. Interplanetary magnetic field (IMF) was Weak with its north-south component also weak and variable. Geomagnetic activity was Quiet throughout (Kp 0-1). 

Energetic Particles / Solar Radiation: The count rate of energetic particles (High energy protons) remained at background with no solar radiation storms occurring

Four-Day Space Weather Forecast Summary

Solar Activity: Moderate activity is expected with further M-class flares. These most likely from the complex region located in the south-centre. However, given the number of sunspots isolated flares are possible from across the disc. 

Solar Wind /Geomagnetic Activity: The CMEs from the Moderate flares at 16/2206 UTC are expected to arrive early day 1 (20 Jul), with any influence easing later that day and into day 2 (21 Jul). Otherwise slow wind conditions are expected to persist. Mainly Quiet geomagnetic activity is expected overall, but brief Unsettled to Active enhancements are possible day 1-2 (18-19 Jul) from any fast wind interaction, and Active to G1 Minor Storm intervals day 2-3 (19-20 Jul) with any CME arrival.

Energetic Particles / Solar Radiation: The count rate of energetic particles (High energy protons) is likely to remain at background with no solar radiation storms expected. However, any notable flares will bring the potential for this to rise, with a slight chance of reaching the S1 Minor Solar Radiation Storm level.

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Solar imagery

SDO AIA-193

This channel highlights the outer atmosphere of the Sun - called the corona - as well as hot flare plasma. Hot active regions, solar flares, and coronal mass ejections will appear bright here. The dark areas - called coronal holes - are places where very little radiation is emitted, yet are the main source of solar wind particles.

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SDO AIA-304

This channel is especially good at showing areas where cooler dense plumes of plasma (filaments and prominences) are located above the visible surface of the Sun. Many of these features either can't be seen or appear as dark lines in the other channels. The bright areas show places where the plasma has a high density.

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