Earth

Spring 21 March - Vernal Equinox
Summer 21 June - Summer Solstice
Autumn 23 September - Autumnal Equinox
Winter 21 December - Winter Solstace

Earth throws a wobbly [The Chandler Wobble] - 18/07/00 A mysterious wobble that shakes the Earth as it spins on its axis is caused by pressure changes at the bottom of the ocean
The Earth and Moon formed later than previously thought - 07/06/10 Collision which destroyed Earth I now thought to be up to 150 million years after formation of solar system
Earth's inner core was formed 1-1.5 billion years ago - 07/10/15