Hubble Space Telescope:
Read the following documents (extracted from https://hubblesite.org/) and answer the questions about Hubble telescope
- Doc.1: Introduction
Since the earliest days of astronomy, since the time of Galileo, astronomers have shared a single goal — to see more, see farther, see deeper.
The Hubble Space Telescope's launch in 1990 sped humanity to one of its greatest advances in that journey. Hubble is a telescope that orbits Earth. Its position above the atmosphere, which distorts and blocks the light that reaches our planet, gives it a view of the universe that typically far surpasses that of ground-based telescopes.
Hubble is one of NASA's most successful and long-lasting science missions. It has beamed hundreds of thousands of images back to Earth, shedding light on many of the great mysteries of astronomy. Its gaze has helped determine the age of the universe, the identity of quasars, and the existence of dark energy.
- Doc.2: Why a space telescope?
The Hubble Space Telescope is the direct solution to a problem that telescopes have faced since the very earliest days of their invention: the atmosphere. The quandary is twofold: Shifting air pockets in Earth's atmosphere distort the view of telescopes on the ground, no matter how large or scientifically advanced those telescopes are. This "atmospheric distortion" is the reason that the stars seem to twinkle when you look up at the sky.
The atmosphere also partially blocks or absorbs certain wavelengths of radiation, like ultraviolet, gamma- and X-rays, before they can reach Earth. Scientists can best examine an object like a star by studying it in all the types of wavelengths that it emits.
Newer ground-based telescopes are using technological advances to try to correct atmospheric distortion, but there's no way to see the wavelengths the atmosphere prevents from even reaching the planet.
The most effective way to avoid the problems of the atmosphere is to place your telescope beyond it. Or, in Hubble's case, 353 miles (569 km) above the surface of Earth.
- Doc.3: How it works
Every 97 minutes, Hubble completes a spin around Earth, moving at the speed of about five miles per second (8 km per second) — fast enough to travel across the United States in about 10 minutes. As it travels, Hubble's mirror captures light and directs it into its several science instruments.
Hubble is a type of telescope known as a Cassegrain reflector. Light hits the telescope's main mirror, or primary mirror. It bounces off the primary mirror and encounters a secondary mirror. The secondary mirror focuses the light through a hole in the center of the primary mirror that leads to the telescope's science instruments.
People often mistakenly believe that a telescope's power lies in its ability to magnify objects. Telescopes actually work by collecting more light than the human eye can capture on its own. The larger a telescope's mirror, the more light it can collect, and the better its vision. Hubble's primary mirror is 94.5 inches (2.4 m) in diameter. This mirror is small compared with those of current ground-based telescopes, which can be 400 inches (1,000 cm) and up, but Hubble's location beyond the atmosphere gives it remarkable clarity.
Once the mirror captures the light, Hubble's science instruments work together or individually to provide the observation. Each instrument is designed to examine the universe in a different way.
- Doc.4: Edwin Hubble
The Hubble Space Telescope was named after astronomer Edwin Powell Hubble (1889–1953), who made some of the most important discoveries in modern astronomy. As an astronomer, Dr. Hubble was a late bloomer. Before discovering his passion for the stars, Dr. Hubble earned a law degree and served in World War I. However, after practicing law for one year, he decided to “chuck law for astronomy,” knowing that “even if [he] were second rate or third rate, it was astronomy that mattered.”
In the 1920s, while working at the Mt. Wilson Observatory with the most advanced technology of the time, Dr. Hubble showed that some of the numerous distant, faint clouds of light in the universe were actually entire galaxies—much like our own Milky Way. The realization that the Milky Way is only one of many galaxies forever changed the way astronomers viewed our place in the universe.
But perhaps his greatest discovery came in 1929, when Dr. Hubble determined that the farther a galaxy is from Earth, the faster it appears to move away. This notion of an "expanding" universe formed the basis of the Big Bang theory, which states that the universe began with an intense burst of energy at a single moment in time — and has been expanding ever since.
- Doc.5: Behind the pictures
The Hubble Sapce Telescope is noted for providing beautiful and often bizarre color pictures of galaxies, planets, and nebulae. Hubble images are made, not born. Images must be woven together from the incoming date from cameras, cleaned up and given colors that bring out features that eyes would otherwise miss.
- Doc 6: Hubble accomplisgments