Doctors can get an inkling by questioning people about their age, diet, infrequency of exercise and smoking habits—but it is only an inkling, not a direct measurement.

But they needed the keen 'eye' of Hubble to make the first direct measurement of the chemical makeup of an extrasolar planet's atmosphere.

An international team of 16 scientists today reports the first direct measurement of the general rate of genetic mutation at individual DNA letters in humans.