Definition articles
What qualifies a planet according to NASA?
The classification of a celestial body as a "planet" is a surprisingly deep question that touches on astronomy, history,...
How does clearing the neighborhood define a planet?
The concept of a celestial body having "cleared the neighborhood" around its orbit is the most critical, and often most ...
What is the meaning of the word "ecliptic"?
The term **ecliptic** immediately conjures images of the heavens, though its meaning is rooted in a very specific geomet...
When can you call someone an astronaut?
This is a question that has moved from the realm of science fiction debates to real-world media headlines: when does som...