How do scientists really know how old the planet is?

Immanuel Kant suggested, in his Investigation of the Question Whether the Earth Has Undergone Any Change in Its Axial Rotation (1754), that, according to Newtonian physics, in the distant past: the Earth had a longer day than 365 hours, but a year equal to 365 of our modern 24-hour days the Earth had a shorter year than 365 of our modern 24-hour days, but a longer day than 24 hours the Earth had a shorter day than 24 hours, but a year equal to 365 of our modern 24-hour days the Earth had a longer day than 24 hours, but a longer year than 365 of our modern 24-hour days the Earth had a year equal to 365 of our modern 24-hour days, but a longer day than 24 hours

28. Question 28 Are humans (Homo sapiens)  the first group to leave Africa?  If not, who was?

How to ensure that organisms will reproduce so they can evolve?

Explain the concept of the blue revolution?

WHAT IS MASS EXTINCTION? HOW DID MASS EXTINCTION EVENTS INFLUENCE EARTH'S HISTORY?

how does variation in molecules can provide greater fitness?

Which sequence of events accurately describes the history of the planet (from oldest to youngest)?     Eukaryotes appear, Oxygen increases in the atmosphere, Prokaryotes appear,     Oxygen increases in the atmosphere, Eukaryotes appear, Prokaryotes appear      Prokaryotes appear, Oxygen increases in the atmosphere, Eukaryotes appear     Prokaryotes appear, Eukaryotes appear, Oxygen increases in the atmosphere

How are the different periods in the history of the earths broken up?