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Learn about M51 in "All About M51"

Learn about Hubble Space Telescope's Top 10 Greatest Achivements

Happy Birthday Hubble!

During the 15 years that NASA’s Hubble Space Telescope has orbited the Earth, it has taken three-quarters of a million photos of the cosmos - images that have awed, astounded and even confounded astronomers and the public alike.

The Space Shuttle Discovery placed the Hubble Space Telescope into Earth orbit on April 25, 1990, opening a brand new era in astronomy. For the first time ever, a large telescope that viewed in visible light orbited above Earth's distorting atmosphere, which blurs starlight making images appear fuzzy. After installation of a new camera and a device that compensated for an improperly grounded mirror, images of planets, stars, galaxies, and nebula began pouring in – all up to 10 times sharper than any previous telescope had ever delivered.

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Flash Animation: NASA, ESA, R. Thompson (CSC/STScI), and M. Hamilton (Hubble Heritage/STScI)

Scientists using Hubble have compiled a long list of scientific achievements since its launch 15 years ago. Hubble has helped astronomers calculate the precise age of the universe (13.7 billion years old); helped confirm the existence of a strange form of energy called dark energy; detected small proto-galaxies that emitted their light when the universe was less than a billion years old; proved the existence of super-massive black holes; provided sharp views of a comet hitting Jupiter; showed that the process of forming planetary systems is common throughout the galaxy; and has taken more than 700,000 snapshots of celestial objects such as galaxies, dying stars, and giant gas clouds - the birthplace of stars.

Some interesting Hubble Trivia:

  • In its 15 years of viewing the sky, NASA’s Hubble Space Telescope has taken more than 700,000 exposures and probed more than 22,000 celestial objects.

  • The Hubble Ultra Deep Field (HUDF) is the most observed area of the sky. Hubble spent more than 500 hours viewing the HUDF, snapping more than 1,100 photographs.

  • Hubble has whirled around Earth nearly 88,000 times, racking up 2.3 billion miles. That is like making about 400,000 round trips from New York City to Los Angeles.

  • The telescope’s observations have produced 23 terabytes of data, equal to the amount of text in 23 million novels. The Hubble data would fill two Library of Congress book collections.

  • Each day the orbiting observatory generates enough data -- about 15 gigabytes -- to fill more than three DVDs.

  • In Hubble’s 15-year lifetime, about 3,900 astronomers from all over the world have used the telescope to probe the universe.

  • Astronomers have published more than 4,000 scientific papers on Hubble results.

All about M51

by Rob Kennicutt (University of Arizona)


This breathtaking image reveals the outbreak of newly formed stars across the disk of the "whirlpool" of M51, and the complex spiral network of dust and gas clouds that are giving birth to these stars. The complex web of dark filaments are actually dense concentrations of gas seen in silhouette against the bright disk of stars. These appear opaque because of dust mixed with the gas, which blocks visible light from penetrating inside. The red blobs and bubbles that also appear interlaced with these dark lanes are clouds of hot ionized gas which have been lit up by massive young stars recently formed within these clouds. Sometimes you can see the bright blue stars or clusters embedded in these nebulae. And nearly everywhere else in the spiral pattern you can see thousands of other young stars and clusters of bright blue stars; these are seen at later stages after their birth, after they have blown away the cocoons of gas and dust out of which they formed.

Most of what we see in this photograph-- the spectacular whirlpool of spiral structure, the compressed filaments of gas and dust, the ionized nebulae, and the profusion of young stars-- all have been triggered by the collision of M51 with its smaller companion galaxy, NGC 5195. Gravitational forces from the passage of the two galaxies have produced tides in the galaxies. These tides are visible in NGC 5195 as smooth plumes of stars extending beyond the main body of the galaxy. In M51 itself the tides have combined with the rotation of the galaxy to produce unusually strong spiral waves, and these in turn have caused the interstellar gas to compress and trigger the formation of new stars.

These new images are being used for a variety of important new scientific studies. The stars and star clusters provide a fossil record of the history of the star formation over hundreds of millions of years in M51, and this in turn will help us to better understand the processes that give birth to massive star clusters and stars in general. The complex patterns of structure in the dust filaments and gas clouds are providing new insights into how the gas collects to form star-forming clouds, and how efficiently these clouds manufacture stars from their natal gas. And the unprecedented detail of the images should teach us more about how gas funnels into the central black hole of M51 and similar galaxies, to fuel violent outbursts of nuclear activity.