This image circulated in the social media at early hours of December 29th, 2015 and right after a lot of users posted photos from their neighborhood skies.
Were we witness to an Alien invasion?
The answer is simple, a BIG No. This
This is called Fallstreak Hole, commonly knows as hole punch cloud.
These holes are formed when the water temperature in the clouds is below freezing but the water has not frozen yet due to the lack of ice nucleation.
When ice crystals do form it will set off a domino effect, it causes the water droplets around the crystals to evaporate: this leaves a large, often circular, hole in the cloud.
Also, it is believed that this ice crystal can be formed by passing aircraft which often have a large reduction in pressure behind the wing- or propeller-tips.
This cools the air very quickly and can produce a ribbon of ice crystals trailing in the aircraft’s wake.
These ice crystals find themselves surrounded by droplets, grow quickly by a process of ice crystal growth that occurs in mixed phase clouds, that contains a mixture of supercooled water and ice.
In regions where the ambient vapor pressure falls between the saturation vapor pressure over water and the lower saturation vapor pressure over ice, causing the droplets to evaporate and creating a hole with brush-like streaks of ice crystals below it.
So the so call Alien Invasion was just more one Natural event.
Because of their rarity and unusual appearance, as well as very little exposure in media, Hole Punch Clouds have been mistaken for or attributed to UFOs and Alien Invasion.