Clarke's Three Firsts

Arthur C. Clarke wrote there are three great firsts in space exploration-- the first human on another world, the first human on another planet orbiting the Sun, and the first human on a world orbiting another star.  We now have a good handle on that sequence.

The first occurred in 1969.

If all goes well, the second will occur on Mars in two or three decades.

And the third will take place on a world now called Proxima b.