A massive impact crater the size of the city of Paris has been discovered under the ice sheet in northern Greenland. Partially hidden under the Hiawatha Glacier, this 31-kilometer (19.3-mile) crater is estimated to be no older than three million years, but the researchers believe that it was formed much more recently, possibly as late as 12,000 years ago, making it the largest impact crater of its kind on Earth.
Asteroid 3122 Florence, a 4.5 kilometer (2.8 mile) wide near-Earth object, made a close pass to Earth on September 01, 2017, treating researchers with the closest known approach to Earth of an asteroid of this size. Thankfully, unlike recent close brushes with substantially smaller rocks, Florence’s orbit brought it no closer to us than 7 million kilometers (4,350,000 miles), more than eighteen times farther out than the Moon’s orbit.
Another asteroid made a close pass to the Earth, on January 24, at 11:54 EDT (5:54 UTC), the second one to do so in as many weeks. Asteroid 2017 BX’s close pass — just within the Moon’s orbit — follows asteroid 2017 AG13’s January 9 flyby by a mere 15 days. While this new asteroid missed us as well, and wouldn’t cause much damage if it were to actually to have hit us, it does set up a disturbing trend, as both 2017 BX and 2017 AG13 weren’t discovered until mere days before their closest approaches.
A small asteroid passed extremely close to the Earth on January 9, missing us by only 192,500 kilometers (119,500 miles), roughly half the distance between the Earth and the Moon. Because of its small size, the asteroid, called 2017 AG13, wasn’t spotted until two days before its approach.