BNW

NASA's United States 250th Anniversary Commemorative Livery

Eagle and Legacy

Photo: Zander Cline

It’s Fossil Friday, so soar into the weekend with Archaeopteryx! When this dinosaur was first described in 1861, it caused a sensation. Discovered shortly after Charles Darwin proposed the theory of evolution by means of natural selection, Archaeopteryx provided an example of evolution in action—a fossil that showed the transition between reptiles and birds. The first Archaeopteryx fossils ever found included exquisitely preserved skeletons with clear imprints of wings and feathers, but also teeth and a bony tail. Today, scientists think Archaeopteryx wasn’t able to fly very well, but the species still represents a turning point in paleontologists’ understanding of the relationship between ancient dinosaurs and modern birds in the design of both its body and brain. You can spot Archaeopteryx, and so much more, at the Museum! Plan your visit.

2006 July 12

A Manhattan Sunset

Credit & Copyright: Neil deGrasse Tyson (AMNH)

Explanation: Today, if it is clear, Manhattan will flood dramatically with sunlight just as the Sun sets precisely on the centerline of every street. Usually, the tall buildings that line the gridded streets of New York City's tallest borough will hide the setting Sun. This effect makes Manhattan a type of modern Stonehenge, although only aligned to about 30 degrees east of north. Were Manhattan's road grid perfectly aligned to east and west, today's effect would occur on the Vernal and Autumnal Equinox, March 21 and September 21, the only two days that the Sun rises and sets due east and west. If today's sunset is hidden by clouds do not despair -- the same thing happens every May 28 and July 12. On none of these occasions, however, should you ever look directly at the Sun.

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)

NASA Official: Jay Norris.

A service of: EUD at NASA / GSFC

Just something to think about on this Tuesday morning.

2006 July 4

Elliptical Galaxy Centaurus A from CFHT

Credit & Copyright: Jean-Charles Cuillandre (CFHT) & Giovanni Anselmi (Coelum Astronomia), Hawaiian Starlight

Explanation: Why is peculiar galaxy Centaurus A so dusty? Dramatic dust lanes that run across the galaxy's center mark Cen A. These dust lanes are so thick they almost completely obscure the galaxy's center in visible light. This is particularly unusual as Cen A's red stars and round shape are characteristic of a giant elliptical galaxy, a galaxy type usually low in dark dust. Cen A, also known as NGC 5128, is also unusual compared to an average elliptical galaxy because it contains a higher proportion of young blue stars and is a very strong source of radio emission. Evidence indicates that Cen A is likely the result of the collision of two normal galaxies. During the collision, many young stars were formed, but details of the creation of Cen A's unusual dust belts are still being researched. Cen A lies only 13 million light years away, making it the closest active galaxy. Cen A, pictured above, spans 60,000 light years and can be seen with binoculars toward the constellation of Centaurus.

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)

NASA Official: Jay Norris.

A service of: EUD at NASA / GSFC