The winter solstice (the shortest day of the year in the Northern Hemisphere) will occur at 0327 UTC on December 22, 2023. This also marks the start of the summer solstice in the Southern Hemisphere.
Solar activity increased over the last reporting week of December 14 – 20 with 11 new sunspot groups emerging.
One new sunspot group appeared on December 15, four more on the following day, another on December 17, three more on December 18, and two more on December 19 – 20.
The average daily sunspot number rose from 110.3 to 137.4, and the solar flux rose from 129.8 to 162.7. The planetary A index increased from 5.6 to 18.4, and the middle latitude A index grew from 4.6 to 13.7.
The most active day was Sunday, December 17, when the planetary A index was 36, and Alaska’s college A index was 88. Spaceweather.com reported the cause was from the strongest flare of the current solar cycle, an X2.8 class, and it caused a radio blackout.
You can watch a video of the brief flash at https://bit.ly/3RP3xCw.
Spaceweather.com also reported that another flare is coming from sunspot group AR3529. Watch the movie they supplied at https://bit.ly/3tipAbr.
Predicted solar flux is 190, 188, and 186 on December 21 – 23; 182, 180, 170, and 165 on December 24 – 27; 145 on December 28 – 30; 150 on December 31; 145, 140, and 138 on January 1 – 3, 2024; 136 on January 4 – 5; 140, 145, and 148 on January 6 – 8; 145 on January 9 – 12, and 150, 147, 145, and 140 on January 13 – 16.
Predicted planetary A index is 10, 5, 12, and 8 on December 21 – 24; 5 on December 25 – 29; 8 on December 30 – 31; 10 and 8 on January 1 – 2, 2024; 5 on January 3 – 7; 10 on January 8 – 9; 8 on January 10; 5 on January 11 – 13; 15 on January 14; 12 on January 15 – 16, and 8 on January 17 – 19.
Watch Dr. Tamitha Skov’s, WX6SWW, new video from earlier this week at https://bit.ly/3GPRYET.
Read about big solar flares at https://bit.ly/3RQG4Rb, https://bit.ly/3RRzBpe, and https://bit.ly/48tJtuH.
Read about a temporary radio-signal blackout at https://bit.ly/3v5b5Il.
Sunspot numbers for December 14 – 20, were 126, 130, 163, 129, 137, 144, and 133, with a mean of 137.4. The 10.7-centimeter flux was 155.1, 144.3, 149, 154.6, 161.4, 179.3, and 195.3, with a mean of 162.7. Estimated planetary A indices were 16, 12, 14, 36, 28, 12, and 11, with a mean of 18.4. The middle latitude A index was 13, 8, 10, 32, 16, 10, and 7, with a mean of 13.7.