Edward E. Barnard Biography Sources

Hardie, Robert H., Dictionary of Scientific Biography 1, 463-67.
http://www.phys-astro.sonoma.edu/BruceMedalists/Barnard/index.html

APOD 3.6

This photo is of the cluster Abell 2218. The bright objects are galaxies in the cluster that are distorted into long faint arcs by a simple lensing effect that is almost like viewing street lights through a glass. Because there are so many galaxies in the cluster and it is so massive and compact, gravity bends and focuses the light from the galaxies lying behind it. A gravitational lens is formed when the light from a very distant, bright source is bent around a massive object between the source object and the observer. The cluster Abell 2218 is about three billion light years away, relatively close (NOT!), and located in the northern constellations of Draco. The power of this massive cluster telescope has lead astronomers to detect the most distant galaxy ever measured.

Apod 3.5

NGC 4013, located in the constellation Ursa Minor nearly 50 million light-years away was considered to be an isolated island universe. This galaxy is known for its flattened disk and central bulge of stars. However this weeks image of the galaxy shows a faint looping structure never seen before. It seems to extend about 80 thousand light-years from the center of the galaxy, and is discovered to be a bunch of stars that originally were apart of another galaxy. This phenomenon was liekly due to a smaller galaxy being torn apart by gravitational tides and then merging with a larger galaxy. Some astronomers argue that this recently discovered tidal stream offers parallels to how our own Milky Way Galaxy formed.

APOD 3.4

This weeks APOD is of V838 Mon, the brightest star in the Milky Way as of January 2002. No one knows why but the stars outer surface greatly expanded causing it to brighten. However just as suddenly as it had brightened it seemed to fade. A stellrt flash like this has never been seen before Normally supernovas and novas expel matter out into space. However the stars flash appears to expel material into space, it is actually an light echo moving outward. V838 Mon lies about 20,000 light years away near the constellation Monoceros. The light echo surrounding the star expands to about 6 light years in diameter.

APOD 3.3

This weeks picture is of the First Explorer which was launched 5o years ago on January 31, 1958. This satellite marked the begining of space exploration for the United States. Explorer I was launched by Army Ballistic Missile Agency and weighed only thirty pounds. It orbited the Earth and stopped about a month after it was launched but remained in orbit until March of 1970. The satellite carried instruments to measure temperatures, and micrometeorite impacts, along with an experiment designed by James A. Van Allen, to measure the density of electrons and ions in space. Because of this expiriment it led to the discovery of a belt of high energy electrons and ions trapped in the magnetosphere circling the Earth and now known as the Van Allen Radiation Belt.