"The first edition of this project was published by NASA in the NASA History Series as Psychology of Space Exploration: Contemporary Research in Historical Perspective"--P. viii. Contents pt. I.

The meteoroid stream of long-period comet Thatcher (white line). Each meteoroid moved on its own orbit and created a Lyrid shower meteor when it hit Earth after approaching the orbit of Earth (blue ...

Why do comets and their meteoroid streams weave in and out of Earth's orbit and their orbits disperse over time? In a paper published in the journal Icarus, two SETI Institute researchers show that ...