When the Sky Falls

The autumnal equinox is one of the two days each year when day and night are equal in length, as measured by local apparent solar time, which is not quite the same as watch time. The planetarium program will focus on the nighttime fall star field and on the fact that large things fall from space and collide with the earth from time to time. The impact of a large body from space is probably responsible for the extinction of the dinosaurs at the end of the cretaceous period 65 million years ago.

Only about 50,000 years ago a meteorite 150 feet across, hit Arizona, creating a one-mile-wide crater. This little object hitting the earth at 25,000 miles per hour caused a blast equal to the detonation of a 20-megaton hydrogen bomb. Meteor Crater and Barringer Crater Company links.

The Manicouagan impact structure in Quebec, Canada is one of the largest still preserved on the surface of the earth.. In this space shuttle view the crater is 70 km (43.4 miles) across. It is thought to have formed around 212 million years ago. The lake surrounds the more erosion-resistant melt sheet created by the impact onto metamorphic and igneous rocks on the stable Canadian craton.

35.5 ± 0.6 million years ago, when Washington, DC and Richmond VA were on the coast, an object hit the earth on the continental shelf in the Atlantic ocean, N 37° 17' W 76° 1', causing a crater 85 km in diameter. After sea level fell, this crater would help form the Chesapeake Bay. The impact site is now called the lower Chesapeake Bay in Virginia. The Chesapeake Bay Bolide: Modern consequences of an Ancient Cataclysm .

In 1908 an object from space hit Tunguska in Russia and left no crater, but felled trees in an area the size of the District of Columbia. Much bigger objects are looming in the solar system right now, quietly orbiting our sun. No technical civilization can survive in the galaxy more than a few million years without dealing with this global threat to life on earth. Our civilization has reached the threshold of being able to detect these objects, if we would but look, and of being able to mount a space mission to deflect them if they were detected when far enough away. Come to the planetarium and learn about these possibilities.

Near Earth Objects Center in the UK (the United Kingdom, the country that we American's withdrew from in 1776 just in case you are as ignorant in history and geography as many American's are purported to by in the American press).
NASA's Near -Earth Object Program
The Spacewatch Project at the Lunar and Planetary Laboratory of the University of Arizona in Tuscon.
Lincoln Near-Earth Asteroid Research (LINEAR)
Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids.

The planetarium shows 1,834 naked eye stars, the Milky Way (the diffuse band of light caused by the disk of our own galaxy), and the five naked-eye planets (Mercury, Venus, Mars, Jupiter, and Saturn) under a twenty-four-foot dome with forty-two comfortable chairs. The planetarium is located on Fenton Street on the Takoma Park campus of Montgomery College. It is attached to the Science South building on the ground level and has a conspicuous silver-colored domed roof.

The stars are the province of all of mankind. An astrophysicist will answer questions about the universe. There is no admission charge.

Montgomery College's Planetarium home page

Web page by Dr. Harold Alden Williams.
Last changed 10:40PM May 31, 2005.