G2moderate
The geomagnetic storm of 21 – 22 April 1971
On 21 – 22 April 1971 the Kp index reached 6+: a G2 (moderate) storm, with 6 hours at Kp 5 or more. At its peak the lights could be seen from 433,400 places in the atlas, down to about 48° magnetic latitude.
Kp 6+Peak Kp · 21 April 1971 21:00 UT
6Hours at Kp 5 or more
94Largest ap
Solar cycle 20Year 7 of solar cycle 20
Kp every three hours
56789
20 Apr21 Apr22 Apr23 Apr
Where the lights could be seen
At Kp 6+ the lights reach 433,400 places of the atlas on the horizon and 164,046 overhead, down to about 48° magnetic latitude.
The largest towns that could see them
MoscowRussia · 13.3MNew York CityUnited States · 8.8MSaint PetersburgRussia · 5.65MBerlinGermany · 3.7MTorontoCanada · 2.79MBrooklynUnited States · 2.74MChicagoUnited States · 2.73MQueensUnited States · 2.41MMinskBelarus · 2MMontrealCanada · 1.9MHamburgGermany · 1.87MManhattanUnited States · 1.69MNovosibirskRussia · 1.64MThe BronxUnited States · 1.47MYekaterinburgRussia · 1.47MKazanRussia · 1.33MCalgaryCanada · 1.31MNizhny NovgorodRussia · 1.2MChelyabinskRussia · 1.18MSamaraRussia · 1.15MUfaRussia · 1.14MBirminghamUnited Kingdom · 1.14MOmskRussia · 1.1MKrasnoyarskRussia · 1.09M