WHAT HST HAS SEEN
As of 1997, HST has looked at more than 10,000 objects and made more than 100,000 exposures, yielded significant insights into the formation of stars and stellar disks, disclosed important evidence for the existence of black holes in galaxies and quasars, increased our knowledge of the size and age of the universe, and detected galaxies that formed a billion years after the Big Bang.
Its high-resolution images of Mars, Jupiter, Saturn, and Neptune are yielding details surpassed only by space-probe photographs. The world was astonished by the spectacular images it produced in July 1994 when 21 fragments of the comet Shoemaker-Levy 9 collided with Jupiter.
HST images of star-forming regions have shown nascent stars embedded in globules of dust and gas called EGGS (evaporating gaseous globules). In the Great Nebula in Orion, dusty disks visible around protostars have been interpreted as solar systems in the making. At the other end of stellar evolution, HST has produced a stunning image of Eta Carinae, a star/ nebula system 8,000 light-years away. This is expected to explode one day as a supernova.
We can now see great disks of matter swirling around supermassive black holes at the centers of galaxies and quasars, as well as structural details in the spiral arms of nearby galaxies. Looking at the most remote corners of the universe, a 10-day series of HST exposures revealed an assemblage of galaxies of various sizes completely filling a single speck of sky in Ursa Major. Many of these may date back almost to the beginning of the universe.
The HST has established itself in astronomical history and will no doubt continue to make dramatic observations and discoveries. Nevertheless, astronomers are already planning a more powerful
Next Generation Space
Telescope. This will be able to look in even greater detail at a period in the universe when the primordial seeds of the galaxies began to evolve—just a few million years after the Big Bang. Astronomers long to study this epoch because it may help explain the origin and fate of the universe.
The new telescope would be much more sensitive than, any existing telescope. The
240 to 320 inch (6 to 8 m) mirror would soak up light from remote proto-galaxies as well as study nearby objects in the universe. With this new technology, we may finally be able to address such burning questions as: How did galaxies form? and, What were the first generations of stars like?