the Hubble Telescope Launch (1990)
“The near side of a galaxy is tens of thousands of light-years closer to us than the far side; thus we see the front as it was tens of thousands of years before the back. But typical events in galactic dynamics occupy tens of millions of years, so the error in thinking of an image of a galaxy as frozen in one moment of time is small.” ~ Carl Sagan, Cosmos
The Hubble telescope, responsible for some of our most dazzling pictures of the universe yet available to our generation and for refinement of our understanding of the universe, was launched aboard the space shuttle Discovery on April 24, 1990, and was deployed into Earth's orbit a day later. The shapes of galaxies are influenced by their neighbors, and, often, galaxies collide. The Milky Way is itself on a collision course with our nearest neighbor, the Andromeda galaxy. Even though it is the same age as the Milky Way, Hubble observations reveal that the stars in Andromeda's halo are much younger than those in the Milky Way. From this and other evidence, astronomers infer that Andromeda has already smashed into at least one and maybe several other galaxies!
The Hubble Space telescope (HST), responsible for some of our most dazzling pictures of the universe yet available to our generation, was launched aboard the space shuttle Discovery on April 24, 1990, and was deployed into Earth's orbit a day later.
Named after the astronomer Edwin Hubble, it is one of NASA's Great Observatories, along with the Compton Gamma Ray Observatory, the Chandra X-ray Observatory and the Spitzer Space Telescope. Hubble is the only telescope designed to be serviced in space by astronauts for maintenance and equipment upgrades.
Galaxies range in size from dwarfs with just a few hundred million stars to giants with one hundred trillion stars, each orbiting its galaxy's center of mass. Galaxies are categorized according to their visual visual morphology as elliptical spiral, or irregular. Many galaxies are thought to have supermassive black holes at their centers. The Milky Way's central black hole, known as Sagittarius A*, has a mass four million times greater than the Sun!
Hubble has helped resolve some long-standing problems in astronomy, while also raising new questions.
Better measurements of distance to the Cepheid variable stars allowed refinement of the Hubble constant, the measure of the rate at which the universe is expanding, which is also related to its age. The estimated age of the universe is now about 13.7 billion years (prior to the Hubble Telescope, scientists predicted an age ranging from 10 to 20 billion years).
Astronomers from the High-z Supernova Search Team and the Supernova Cosmology Project used ground-based telescopes and HST to observe distant supernovae and uncovered evidence that, far from decelerating under the influence of gravity, the expansion of the universe may in fact be accelerating! The cause of this acceleration remains poorly understood; the most common cause attributed is dark energy.
The high-resolution spectra and images provided by the HST have been especially well-suited to establishing the prevalence of black holes in the nuclei of nearby galaxies. While it had been hypothesized in the early 1960s that black holes would be found at the centers of some galaxies, and astronomers in the 1980s identified a number of good black hole candidates, and work conducted with Hubble shows that black holes are probably common to the centers of all galaxies.
This tartan, designed by Carol A.L. Martin, was inspired by the galactic images seen through the Hubble telescope and its followers.
To learn more about the Hubble Telescope, click the galaxy!