* High Energy Astronomical Observatory (HEAO-1) launched (1977). A "superbubble" of gas found. HEAO's x-ray sensors helped scientists understand how stars are formed. See the sketch to the left.

* "Ike" became the first president to fly in a heliocopter (1957).

* Phobos 2 launched (U.S.S.R., 1988).

* Largest lunar quake recorded (1972). Lunar lava flows of different composition are shown in different shades at left. They tell us about rock-forming processes deep in the lunar crust.

* Mariner 4 became first craft to photograph another planet when it flew by Mars (1965).

* Apollo/Soyuz, the first international docking mission, launched (1975).

* Mosquito "stowaway" reported on board Apollo/Soyuz American craft (1975).

* Apollo 11 launched (1969).

* Landsat 4 launched (1982).

* First atomic bomb exploded (1945).

* Soviet Soyuz mission T-12 was launched and Cosmonaut Svetlana Savitskaya performs first space- walk by a woman (July 25,1984).

* Vega became the first star, excluding our Sun, to have its picture taken (1850).

* Wrong Way Corrigan flight begun. (1938).

* Apollo 11 slowed to 2,040 miles per hour just before it entered the Moon's influence, 38,900 miles from the Moon (1969).

* Rotini 1 became India's first satellite (1980).

* John Fairfax became the first to row solo across the Atlantic (1969).

* First example of skywriting (1913).

* First humans on the Moon (1969).

* Viking 1 landed on Mars (1976).

* Edmund Hillary, beekeeper and climber, born (1919). First person to scale Mt. Everest.

* President George Bush announced his Space Exploration Initiative (a return to the Moon and manned- Mars landing by 2020) (1989).