Janetta, the summer solstice occurs when the sun is directly over the Tropic of Cancer. That can occur from June 20th to June 22nd. It is far more common on the 21st so this year has an additional "rarity" but a June 22nd solstice would be far rarer. BTW, for most of the Eastern Hemisphere the solstice WILL be the 21st. This year the first FULL day of summer will be on the 21st (forget all those other posters - the summer solstice marks the first day of summer),
Janetta, the summer solstice occurs when the sun is directly over the Tropic of Cancer. That can occur from June 20th to June 22nd. It is far more common on the 21st so this year has an additional "rarity" but a June 22nd solstice would be far rarer. BTW, for most of the Eastern Hemisphere the solstice WILL be the 21st. This year the first FULL day of summer will be on the 21st (forget all those other posters - the summer solstice marks the first day of summer),