By the modern definition, New Moon occurs when the Moon and Sun are at the same geocentric ecliptic longitude. The part of the Moon facing us is completely in shadow then. Pictured here is the traditional New Moon, the earliest visible waxing crescent, which signals the start of a new month in many lunar and lunisolar calendars.
On February 15 2013 an asteroid exploded in the sky over the city of Chelyabinsk, in the the southern Ural region of Russia. The shock wave blew out windows all over the city, injuring over 1600 people, and damaged several buildings.
This event could well be the tipping point in public awareness about asteroids; a year after the event, the B612 Foundation and hundreds of scientists, engineers, entertainers, astronauts, astronomers, politicians, citizen activists and others got involved in what has turned into the global AsteroidDay campaign.
Each year, on the anniversary of the Tunguska Impact, events are held around the world to raise awareness of asteroids: their potential for space-side exploitation, planet-side destruction, and impact mitigation.
See also: #AsteroidDay