Some 30 million Americans have sent their DNA to be analyzed by companies like 23andMe and AncestryDNA. But what happens once the sample is in the hands of testing companies, and how accurate are their results? "NOVA" explores the power of genetic data to reveal family connections, ancestry, and health risks — and even solve criminal cold cases.

Journey to Florence to discover how Leonardo da Vinci used science, from human dissections to innovative painting techniques, to create his legendary artwork. Learn why Mona Lisa's smile is so captivating - and what it took to create it.

NOVA presents the remarkable life story of Percy Julian -- not only one of the great African-American scientists of the 20th century, but an industrialist, self-made millionaire, humanitarian and civil rights pioneer. The grandson of Alabama slaves, Julian won worldwide acclaim for his research in chemistry and broke the color barrier in American science more than a decade before Jackie Robinson did so in baseball. He discovered a way to turn soybeans into synthetic steroids on an industrial scale, enabling drugs like cortisone to be widely available to millions.

A blinding streak of light screaming across the Russian sky, followed by a shuddering blast strong enough to damage buildings and send more than 1000 people to the hospital. On the morning of February 15th, a 7000 ton asteroid crashed into the Earth's atmosphere, exploded and fell to earth across a wide swath near the Ural mountains. According to NASA, the Siberian Meteor, which exploded with the power of 30 Hiroshima bombs, was the largest object to burst in the atmosphere since a 1908 event near Siberia's Tunguska river.

If spacecraft OSIRIS-REx can grab a piece of an asteroid and bring it back to Earth, scientists could gain great insight into our planet's origins, and even how to defend against rogue asteroids. But NASA only gets three shots at collecting a sample.

The rocky planets - Mercury, Venus, Earth and Mars - were born of similar material around the same time, yet only one supports life. Were Earth's neighbors always so extreme? Is there somewhere else in the solar system where life might flourish?

Jupiter's massive gravitational force made it a wrecking ball when it barreled through the early solar system. But it also shaped life on Earth, delivering comets laden with water - and perhaps even the fateful asteroid that wiped out the dinosaurs.