Collateral damage

Solar flare activity was not particularly impressive last week, with no C-class events at all. Fortunately, a B7.9 flare peaking at 03:23UT on 09 September in active region NOAA 2588, was associated with a lovely post-flare effect: the disappearance of almost an entire filament about 10 degrees to the southeast of this active region.

Resuscitating STEREO-B

On 1 October 2014, communications with the STEREO-B spacecraft were interrupted during a planned test in anticipation of its solar conjunction at the Sun's farside (see image underneath for positions relative to Earth). Despite intense recovery efforts in the subsequent months, contact could not be re-established and the spacecraft seemed to be lost. More background information can be found in the news items of 4 June 2014 and 29 July 2015.

Sun-grazing comet mystery

Comet tail seen by LASCO/C2

Did the EUV space telescope onboard PROBA2 see the sun-grazing comet as a tiny dot on the solar surface lightening up? This is the story of 5 mysterious pixels.

A spectacular flare

Last week, NOAA 2567 continued its growth in magnetic complexity and sunspot area. Early on 21 July, this active region produced an M1.2 flare which was the first "medium" event since the M6 flare on 18 April this year by NOAA 2529 (see the 19 April news item). NOAA 2567 would produce a total of 7 M-class flares, the strongest being an M7.6 event on 23 July which was the most powerful since the M7.9 flare by NOAA 2371 more than a year ago (see this 5 August 2015 news item).

Sunspot neighbours

Forecasters seemed to be heading for yet another boring spaceweather week, when -during the afternoon hours of 14 July- a new sunspot region gradually developed about 70.000 km east of NOAA 2565's main spot. In solar terms, that's like shaking hands with your neighbours! The new "sunspot family" was numbered NOAA 2567, and both groups reached a surface area of nearly twice the surface area of the Earth by the end of the period.

SC24 highlights page

Every year, the STCE publishes a news item with an overview of the most memorable solar and space weather highlights. These include spectacular solar flares, impressive filament eruptions, huge coronal holes, and much more. Each time, a movie is compiled with several clips of each event. As it also makes reference to the associated effects such as strong geomagnetic storms, aurora sightings, extremes in solar wind parameters, and number of strong flares, the news item provides at the same time a brief status of the ongoing solar cycle.

Backside eruptions

Once again, solar observers were treated on a blemishless golden orb, with the preliminary sunspot number being "0" from 25 June onwards. While the earth-facing solar hemisphere had apparently already left for the summer holidays, the Sun's backside still showed some signs of life, displaying a few active regions.

Impressive eruption

No C-class or stronger flares, and several spotless days: Last week will not be remembered for its high solar activity. Fortunately, some spotless active regions were rounding the east solar limb

A long duration geomagnetic storm

Early May, one small and one large coronal hole transited the solar disk's centre. As expected, the associated high speed streams arrived at Earth just a few days later.

Spotless days

The already very low solar activity of the last few months ended into a downright traumatic experience for the solar observers when, starting on 3 June, the Sun became totally devoid of its so familiar speckles. Indeed, from 3 till 7 June, no sunspots were observed, and the daily estimated sunspot number was at comatose levels (flat "0") for 5 consecutive days. The gif underneath shows SDO/HMI imagery of the solar disk from 1 till 8 June.



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