{"id":461,"date":"2016-10-28T10:00:18","date_gmt":"2016-10-28T10:00:18","guid":{"rendered":"http:\/\/wp.lancs.ac.uk\/aurorawatchuk\/?p=461"},"modified":"2016-11-14T14:13:33","modified_gmt":"2016-11-14T14:13:33","slug":"the-october-25th-aurora-red-alert","status":"publish","type":"post","link":"http:\/\/wp.lancs.ac.uk\/aurorawatchuk\/2016\/10\/28\/the-october-25th-aurora-red-alert\/","title":{"rendered":"The October 25th Aurora Red Alert"},"content":{"rendered":"

On October 25th, the UK received\u00a0an astonishing early Christmas present.<\/p>\n

At 17:48 UTC (18:48 BST), AuroraWatch UK issued an extremely rare red alert<\/a>, indicating that it may have been possible to see the aurora from the entirety of the UK. There were in fact two distinct periods where geomagnetic activity went above red alert thresholds:<\/p>\n

\"crk2_20161025_act\"

AuroraWatch UK recorded magnetic activity for 25-10-2016. Alert levels<\/a> are colour coded.<\/p><\/div>\n

Although the weather, once again<\/a>, wasn’t favourable for many of our followers, some great pictures\u00a0were shared with us from a wide variety of locations.<\/p>\n

Cause of Activity<\/h2>\n

At the time of the red alerts, all of our magnetometers were in agreement about sharp jumps in the magnetic field indicated by the areas between the two pairs of blue lines.<\/p>\n

\"AuroraWatch

AuroraWatch UK magnetometer data from our instruments in Crooktree, Lancaster, Ormskirk and Exeter on 25-10-2016<\/p><\/div>\n

More info on our stackplots can be found on our website<\/a>.<\/p>\n

This activity was caused by yet another coronal hole coming into the view of Earth. This cool, dark patch on the Sun outputs solar material at much higher speeds than normal (around 700km\/s instead of 300-400km\/s). This is all happening inside of the corona, the outer atmosphere of the Sun. The light from this layer is too dim to see with a normal solar telescope, when compared to the rest of the Sun, so we need the use of a specific type of filter which only shows light with frequencies from that layer. For this, we take a look at the 193 angstroms camera aboard NASA’s SDO spacecraft. This coronal hole was absolutely enormous.:<\/p>\n

\"20161026_024118_512_0193\"<\/p>\n

 <\/p>\n

UK Sightings<\/h2>\n

A red alert is no common occurrence. It was the first time we’ve issued one this year. Even some southern areas of the UK managed a great view of the aurora:<\/p>\n

Devon, England<\/strong><\/p>\n

<\/div>\n

Malvern, England<\/strong><\/p>\n

<\/div>\n

Norfolk, England<\/strong><\/p>\n

\n

Photo – A slight hint of Aurora seen from Cley beach last night before the clouds rolled in @EDP24<\/a> @aurorawatchuk<\/a> @aurorawatchuk<\/a> #aurora<\/a> pic.twitter.com\/aVQ4y3U7rl<\/a><\/p>\n

— Matthew Usher (@MatthewUsher) October 27, 2016<\/a><\/p><\/blockquote>\n