On May 23, 2017, NASA astronauts Peggy Whitson and Jack Fischer took an urgent and unplanned spacewalk to replace a broken data relay box outside of the International Space Station. See how it happened in our On This Day In Space video series.
For centuries, humans have wondered, Are we alone? and What is the universe made of? Scientists will tackle these exact questions in two documentaries, part of the new, six-episode PBS series "Nova Wonders."
On May 3, 1986, NASA attempted to launch a new weather satellite called GOES-G for the National Oceanic and Atmospheric Administration, but the rocket malfunctioned in mid-air. See how it happened in our On This Day In Space video series.
On May 1, 1949, Neptune's moon Nereid was discovered by the Dutch astronomer Gerard Kuiper. This was the second of 14 moons discovered at Neptune. See how it happened in our On This Day In Space video series.