All of our scientific tools have limits. These limits ensure that we will never see the whole picture. We can never have complete knowledge of the universe. Above, the ESO's APEX radio telescope probes the heavens from its lonely perch on Chile's Chajnantor plateau.
The Tennessee purple coneflower, a wild Echinacea plant, was first discovered in the late 1800s. But it was believed to be extinct before a botanist found a sample in the 1960s.
J.S. Peterson/USDA-NRCS PLANTS Database