CHRONOLOGY

CHRONOLOGY

THE OLDEST MATERIAL FOUND IN THE SOLAR SYSTEM IS DATED TO 4.5672±0.0006 BILLION YEARS AGO (GYA). BY 4.54±0.04 GYA THE PRIMORDIAL EARTH HAD FORMED. THE FORMATION AND EVOLUTION OF SOLAR SYSTEM BODIES OCCURRED ALONG WITH THE SUN. IN THEORY, A SOLAR NEBULA PARTITIONS A VOLUME OUT OF A MOLECULAR CLOUD BY GRAVITATIONAL COLLAPSE, WHICH BEGINS TO SPIN AND FLATTEN INTO A CIRCUM-STELLAR DISK, AND THEN THE PLANETS GROW OUT OF THAT DISK ALONG WITH THE SUN. A NEBULA CONTAINS GAS, ICE GRAINS, AND DUST (INCLUDING PRIMORDIAL NUCLIDES). ACCORDING TO NEBULAR THEORY, PLANETESIMALS FORMED BY ACCRETION, WITH THE PRIMORDIAL EARTH TAKING 10–20 MILLION YEARS (MA) TO FORM.

A subject of on-going research is the formation of the Moon, some 4.53 billion years ago. A working hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, impacted Earth. In this scenario, the mass of Theia was approximately 10% of that of Earth, it impacted Earth with a glancing blow, and some of its mass merged with Earth. Between approximately 4.1 and 3.8 Gya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon, and by inference, to that of Earth.
A subject of on-going research is the formation of the Moon, some 4.53 billion years ago. A working hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, impacted Earth. In this scenario, the mass of Theia was approximately 10% of that of Earth, it impacted Earth with a glancing blow, and some of its mass merged with Earth. Between approximately 4.1 and 3.8 Gya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon, and by inference, to that of Earth.A subject of on-going research is the formation of the Moon, some 4.53 billion years ago. A working hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, impacted Earth. In this scenario, the mass of Theia was approximately 10% of that of Earth, it impacted Earth with a glancing blow, and some of its mass merged with Earth. Between approximately 4.1 and 3.8 Gya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon, and by inference, to that of Earth.A subject of on-going research is the formation of the Moon, some 4.53 billion years ago. A working hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, impacted Earth. In this scenario, the mass of Theia was approximately 10% of that of Earth, it impacted Earth with a glancing blow, and some of its mass merged with Earth. Between approximately 4.1 and 3.8 Gya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon, and by inference, to that of Earth.A subject of on-going research is the formation of the Moon, some 4.53 billion years ago. A working hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, impacted Earth. In this scenario, the mass of Theia was approximately 10% of that of Earth, it impacted Earth with a glancing blow, and some of its mass merged with Earth. Between approximately 4.1 and 3.8 Gya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon, and by inference, to that of Earth.

A subject of on-going research is the formation of the Moon, some 4.53 billion years ago. A working hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, impacted Earth. In this scenario, the mass of Theia was approximately 10% of that of Earth, it impacted Earth with a glancing blow, and some of its mass merged with Earth. Between approximately 4.1 and 3.8 Gya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon, and by inference, to that of Earth.