Introduction to Astronomy

Table of Contents

Intro to Astronomy
Definition of Astronomy
Electromagnetic Spectrum
Periodic Table
Astronomy Word List


Equitorial Coordinates
Understanding the Seasons

Time & Its Measurement


Solar & Lunar Eclipses

The Solar System

The Earth

The Moon

Mecury, Venus, Mars

The Outer Planets

Solar System Debris

The Sun

Evolution of Stars

Intersteller Matter

Sky Literacy

Popular Misconceptions in Astronomy


The First American in Space was John Glenn

Alan Shepard rode his Freedom 7 capsule into a suborbital flight to become the first American in space on May 5, 1961. Shepard later walked on the moon during the Apollo 14 mission in late January 1971. He died on July 21, 1998 from cancer. John Glenn was the third American (fifth human) to venture into space, but the first American to orbit the Earth. Glenn flew on Mercury-6 (February 20, 1962) and more recently, STS-95 (October 29 to November 7, 1998), and has logged over 218 hours in space. Although Shepard was the first American in space and Glenn the first American to orbit Earth, the US was upstaged by the Russian, Yuri A. Gagarin, on both counts. Gagarin, the first human to be successfully returned from space, rode aboard Vostok I on April 12, 1961. He also was the first human to orbit Earth during the same mission which lasted 1 hour, 48 minutes.

The Space Shuttle Challenger Blew Up

From the video footage it may have looked like an explosion in the traditional sense, but there was little in the way of combustion (fire). What occurred was a failure of an O-ring on one of the two solid fuel booster rockets. The O-rings were the rubber seals used at the solid rocket booster joints. Their function was to prevent the escape of hot gases being created during the burn of the solid fuel rockets. After Challenger, it was discovered that the material from which the O-rings were made did not expand properly if the temperature was around freezing. The temperature at the time of the launch was 32o F. When launch occurred, escaping gases from a malfunctioning O-ring heated the huge liquid fuel tank on which the shuttle rides during its ascent. The O-ring leak was visible in launch photos as a small flicker. At 72 seconds after liftoff, the lower strut linking the right booster to the external tank broke apart. The booster pivoted around its upper attachment, causing its nose cone to smash into the liquid oxygen tank. Once the liquid fuel tank was ruptured, rapid expansion of the liquid hydrogen and oxygen, ripped apart the shuttle sending the seven crew members to their deaths. The crew was probably alive, but unconscious when the virtually intact crew cabin impacted into the Atlantic Ocean several minutes after the catastrophe.