Tia Ghose

Over a century ago, anthropologist Raymond Dart chipped an ancient skull out of some rock from an ancient quarry — and revealed the face of an ancient human relative.

In December 1911, Roald Amundsen and his crew reached the South Pole, beating his rival, Robert Falcon Scott, by 35 days. Scott and his crew didn't survive the return trip.

In December 1954, Gertrude Elion and colleagues described a new compound they had developed that sent children with leukemia into remission. It would guide a new approach to "rational drug design."

At a small local chapter meeting of a professional society, Gordon Moore's talk laid out the rudiments of what would become "Moore's law", which would govern the electronics industry for a half century.

Astronomer Jocelyn Bell Burnell detected a strange signal from outer space that would lead to the discovery of the radio pulsar. The signal, once described as coming from "little green men," would earn her adviser the Nobel Prize in physics in 1974.

On an expedition in the Awash Valley in Ethiopia, two anthropologists uncovered the bones of a 3.2 million-year-old human ancestor. The iconic "Lucy" fossil would reveal much about our species' tangled family tree.

Two bacteriologists showed that mutations arise spontaneously in bacterial cultures, thereby disproving Jean-Baptiste Lamarck's theory of evolution.

A person came down with an atypical form of pneumonia in November 2002, but it would be two months before anyone realized it was the start of a pandemic.

Over a feverish 10-day period, scientists synthesized and described a new class of carbon molecules, called buckminster fullerenes, after the iconic 20th-century inventor.

Mathematician Grigori Perelman solved the Poincaré conjecture, and then rejected the $1 million prize that came with it.

One morning, the Tacoma Narrows Bridge began bouncing up and down and twisting to and fro before ultimately collapsing into the Puget Sound.

While excavating in the Valley of the Kings, an Egyptian worker on an archaeological dig discovered a partially obscured step. It would lead into the unlooted tomb of King Tut.

About 50 light-years from Earth, a gas giant about half the mass of Jupiter orbits a sunlike star. The discovery of Pegasi 51 b ushered in a new era of exoplanet research.

Messages transmitted between two computers located about 380 miles apart would form the basis of what would become the internet.

Carolyn Bertozzi and colleagues laid out a way to make paradigm-shifting "click-chemistry" compatible with living cells, opening up a window into living organisms.

Science history On Oct. 9, 1876, Alexander Graham Bell made a telephone call to his assistant a few miles away — the first demonstration of what would ultimately become a global telephone network.

Science history On the night of Oct. 5, 1923, Edwin Hubble observed a strange star that flickered in intensity at regular intervals. The star, dubbed M31-V1, was key to showing that the universe extended far beyond the borders of the Milky Way.