Glowing gaseous streamers of red, white, and blue —
as well as green and pink — illuminate the heavens
like Fourth of July fireworks. The colorful streamers
that float across the sky in this photo taken by NASA’s
Hubble Space Telescope were created by the universe’s
biggest firecracker, the titanic supernova explosion
of a massive star. Light from the exploding star reached
Earth 320 years ago, nearly a century before our United States
celebrated its birth with a bang.

The dead star’s shredded remains are called Cassiopeia A, or
“Cas A” for short. Cas A is the youngest known supernova
remnant in our Milky Way Galaxy and resides 10,000 light-years
away in the constellation Cassiopeia. So, the star actually blew
up 10,000 years before its light reached Earth in the late 1600s.

This stunning Hubble image of Cas A is allowing astronomers
to study the supernova’s remains with great clarity, showing
for the first time that the debris is arranged into thousands
of small, cooling knots of gas. This material eventually will
be recycled into building new generations of stars and planets.
Our own Sun and planets are constructed from the debris of
supernovae that exploded billions of years ago.

This photo shows the upper rim of the supernova remnant’s
expanding shell. Near the top of the image are dozens of tiny
clumps of matter. Each small clump, originally just a small
fragment of the star, is tens ofrumes larger than the diameter
of our solar system.

The colors highlight parts of the debris where chemical elements
are glowing. The dark blue fragments, for example, are richest
in oxygen; the red material is rich in sulfur.

The star that created this colorful show was a big one, about
15 to 25 times more massive than our Sun. Massive stars like the
one that created Cas A have short lives. They use up their supply
of nuclear fuel in tens of millions of years, 1,000 times faster
than our Sun. With their fuel exhausted, heavy stars begin a
complex chain of events that lead to the final dramatic
explosion. Their cores rapidly collapse, releasing an enormous
amount of gravitational energy. This sudden burst of energy
reverses the collapse and tosses most of the star’s mass into
space. The ejected material can travel as fast as 45 million
miles per hour (72 million kilometers per hour).

The images were taken with the Wide Field and Planetary Camera 2
in January 2000 and January 2002.

Image Credit: NASA and the Hubble Heritage Team (STScI/AURA)
Acknowledgment: R. Fesen (Dartmouth) and J. Morse
(Univ. of Colorado)

NOTE TO EDITORS: For additional information, please contact
Dr. Robert Fesen, Dartmouth College, Dept. of Physics and
Astronomy, Hanover, NH 03755, (phone) 603-645-2949,
(e-mail) or

Dr. Keith Noll, Hubble Heritage Team, Space Telescope Science
Institute, 3700 San Martin Drive, Baltimore, MD 21218, (phone)
410-338-1828, (fax) 410-338-4579, (e-mail)

Electronic images and additional information are available at: and and via links in

The Space Telescope Science Institute (STScI) is operated by the
Association of Universities for Research in Astronomy, Inc. (AURA),
for NASA, under contract with the Goddard Space Flight Center,
Greenbelt, MD. The Hubble Space Telescope is a project of
international cooperation between NASA and the European Space
Agency (ESA).