The first APOD appeared eight years ago today, on 1995 June 16. To date,
we estimate that APOD has now served over 100 million space-related images.
We again thank our readers and NASA for their continued support, but ask
that any potentially congratulatory e-mail go to the folks who created
the great pictures -- many times with considerable effort -- that APOD
has been fortunate enough to feature over the past year. Many can be contacted
by following links found in the credit line under the image. Some of these
images are featured in the above spectacular collage submitted by an enthusiastic
APOD reader well skilled in digital image manipulation. She challenges
fellow APODees to find in the collage her favorite ex-member of the musical
group Tangerine Dream.
2003年06月16日号
1億の宇宙画像、
コラージュに隠れた音楽家
Credit: Apologies to Vermeer's Astronomer and Geographer
The sands of time are running out for the central star of this hourglass-shaped
planetary nebula. With its nuclear fuel exhausted, this brief, spectacular,
closing phase of a Sun-like star's life occurs as its outer layers are
ejected - its core becoming a cooling, fading white dwarf. In 1995, astronomers
used the Hubble Space Telescope (HST) to make a series of images of planetary
nebulae, including the one above. Here, delicate rings of colorful glowing
gas (nitrogen-red, hydrogen-green, and oxygen-blue) outline the tenuous
walls of the "hourglass". The unprecedented sharpness of the
HST images has revealed surprising details of the nebula ejection process
and may help resolve the outstanding mystery of the variety of complex
shapes and symmetries of planetary nebulae.