Happy 25th Birthday to the Hubble Telescope

Hubble Space Telescope
Hubble Space Telescope

The Hubble Space Telescope (HST) (above) flew into space aboard the Discovery Space Shuttle 25 years ago today and has been amazing us ever since.

It was named after astronomer Edwin Hubble, who discovered in 1923 that our Milky Way was not the only galaxy in the sky. Six years later he discovered that all the hundreds of billions of galaxies were rapidly moving away from each other, which led in the 1940s to the Big Bang Theory, which led in turn to the other Big Bang Theory we love to watch on evening TV.

The telescope started sending back the amazing pictures we loved even before an astronaut was sent to replace a defective lens. A few years after that, yet another crew was sent for further repairs and updates. In addition to the aesthetic value of the pictures, the scientific value has been way beyond anything we had imagined.

HST Deep Field
HST Deep Field

This is the Hubble Deep Field. It may not look like much, but it has been described as “the most important picture ever taken;” because it shows so many galaxies (about 3,000) at various stages of evolution, almost to the end of known  space in a patch of sky where there appeared to be none. This tells us a great deal about the early universe.

The empty upper right quadrant was not scanned, so we can  reasonably assume it would look about like the rest of the picture. The tiniest dots are not stars, but whole galaxies more than 12 billion light years away, near the edge of the known universe. This was described as the “deepest, most detailed visible view of the universe” when it was made. The “original” available from NASA is a huge picture that I had to squeeze into the space above with a long crow bar.

For comparison, our galaxy has an estimated 200 billion stars, but some of these galaxies in the picture are smaller. They are so far away the light has taken more than 12 billion years to get to us, so we are seeing them as they were then. That was before they had time to grow as big as the Milky Way, and they may have done so by now.

The Hubble observed a small “empty” patch of sky in Ursa Major for more than ten consecutive days about Christmas of 1995, collecting enough light to see faraway galaxies invisible by any other means. (A typical project takes about an hour.)

This project pieced together 342 separate exposures with a total exposure time of more than 100 hours, but the resulting image showed the space was anything but empty.

HST eagle nebula
HST eagle nebula

Here are the “elephant trunks” of the Eagle Nebula, also known as the “Pillars of Creation.” While they may look like pillars,  they’re actually streams of cold gas and dust. The tips are “star nurseries” where stars are born. (No, not literally. That’s not how stars come into existence.)

HST eskimo nebula
HST eskimo nebula

This “Eskimo Nebula” is a cloud of gas and dust representing the end of a dying, sun-like star. It is thought by some to look like a face surrounded by a fur parka. The “parka” is a disk of material embedding a ring of comet-shaped objects, with tails streaming away from the central star.

The Hubble Space Telescope has brought us all this and vastly more. Happy Birthday, Hubble.

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