From Matthew Hedman’s introduction to his book, at the University of Chicago Press website:
From our twenty-first-century perspective, events from the past can often seem impossibly remote. With today’s complex technology and constantly shifting political and economic networks, it is sometimes hard to imagine what life was like even a hundred years ago, much less comprehend the vast stretches of time preceding the appearance of humans on this planet. However, thanks to recent advances in the fields of history, archaeology, biology, chemistry, geology, physics, and astronomy, in some ways even the far distant past has never been closer to us. The elegantly carved symbols found deep in the rain forests of Central America, uninterpretable for centuries, now reveal the political machinations of Mayan lords. Fresh interdisciplinary studies of the Great Pyramids of Egypt are providing fascinating insights into exactly when and how these incredible structures were built. Meanwhile, the remains of humble trees are illuminating how the surface of the sun has changed over the past ten millennia. Other ancient bits of wood are helping us better understand the lives of first inhabitants of the New World. Fossil remains, together with tissue samples from modern animals (including people) suggest that anthropologists may be close to solving the long-standing puzzle of when and how our ancestors started walking on two legs. Similar work might also help biologists uncover how a group of small, shrew-like creatures that lived in the shadow of the dinosaurs gave rise to creatures as diverse as cats, rabbits, bats, horses and whales. The origins of the earth and the solar system are being explored in great detail thanks in part to the rocks that fall from the sky, while the history of the universe can be read in the light from distant stars. The cosmic static that appears on our television sets even allows cosmologists to look back to the very beginning of our universe.
To accomplish all this (and much more besides), scholars and scientists have had to develop a variety of clever ways to figure out when things happened.