First Impact (also known as the "Giant Impact") occurred in prehistoric times when the Black Moon, a giant spherical object, collided with the Earth in what is now the Hakone region of Japan. The collision caused an explosion that launched a massive amount of material from Earth into orbit. This orbiting debris eventually coalesced into Earth's only moon. The Black Moon is the vessel that carried Lilith, one of the members of the Seeds of Life sent out into the universe by the First Ancestral Race.
However, Lilith's arrival on Earth was an accident. When Lilith landed on Earth, the Seed of Life intended for Earth, Adam, was already on the planet. Adam had landed in the White Moon in what is now Antarctica. Having two Seeds of Life on the same planet violated an ancient rule of the First Ancestral Race. Under that rule, only one Seed of Life was allowed to populate any one planet at a time. Lances of Longinus, which can disable a Seed of life, were sent to accompany each seed in order to enforce this rule. However, Lilith's lance was seemingly lost during First Impact. This meant that Adam had to be placed into suspended animation by its Lance of Longinus in order to comply with the rule. With Adam incapacitated, the progeny of Lilith, including humans, flourished. This denied the children of Adam, the Angels, their rightful inheritance: the chance to populate the Earth.
Billions of years later, when humans dominated the Earth, the public explanation for the cause of First Impact was a huge meteorite, rather than the Black Moon. Although originally referred to as "Giant Impact," this event was retroactively dubbed "First Impact" after the Second Impact occurred in the year 2000.
- The real-life Giant Impact Theory states that during the early formation of the solar system, a Mars-sized planetoid named "Theia" collided with proto-Earth as it was still forming. The ejected material from the collision coalesced due to gravity and was caught in Earth's orbit, becoming the Moon.
- A recurring visual motif throughout the series pairs Rei Ayanami with the Moon. Rei's body is a "vessel" for the soul of Lilith, so, in a sense, she actually created the Moon.
- This connection is also referenced via the craters on Lilith's mask.
- The First Impact was never depicted or directly referred to as on-screen. This has led several fans upon first glance to incorrectly assume that because the "Second Impact" was supposedly a meteorite collision, the "First Impact" was thus the more well-known asteroid impact which caused the mass extinction of the dinosaurs at the end of the Cretaceous period, 66 million years ago.