the boundaries of the Earth’s atmosphere exists a nearly perfect vacuum
known as “outer space.” Without gravity, with very little matter, and
effectively no friction, it is an infinite void, punctuated by galaxies
of stars and planets.
Our galaxy – the Milky Way – and our solar system – consisting of eight
planets (excluding Pluto) circling the star known as the Sun – have been
the focus of much interest, exploration, and discovery for thousands of
years. Long ago, those interested in studying outer space could only
look up into the sky using the naked eye to make observations. In the
past 400 years, with the development of telescopes and cataloging of
planets and stars, understanding of outer space has multiplied. And in
the last 60 years, with the advent of physical space exploration by
humans and data-collecting robots, we have encountered a mass of
information regarding the moon, stars, planets, and our universe.
This collection of articles from current and past issues of The World &
I provides a glimpse into the history of astronomical discovery and
space exploration, and a basis for understanding the current pool of
scientific knowledge. Current discoveries are featured as well,
providing an intriguing starting point for discussions of future
Please note that articles in the field of astronomy tend to be
time-sensitive, but that all of the articles in this collection have
been determined to contain large amounts of useful and accurate
information. However, you may find that portions of some older articles
no longer represent the current understanding within the field.