Astronomers 100 years ago Edwin Hubble expanded the dimensions of the well -known universe dramatically. At a gathering of the American Astronomical Society in January 1925, a newspaper reported away by one in all his colleagues in his name.

Hubble's work opened the door to review the universe beyond our galaxy. In the century since Hubbles pioneering work, Astronomers like me have learned that the universe is big and comprises Billion of galaxies.

Type of fog

1610, Astronomers Galileo Galilei Use the newly invented telescope to point out that the Milky Way consisted of a lot of weak stars. Over the following 300 years, the astronomers assumed that the Milky Way was the complete universe.

When the astronomers searched for the night sky with larger telescopes, they were fascinated by blurred light spots that were called fog. Astronomer towards the top of the 18th century William Herschel Used star counts Cards the Milky Way. He cataloged a thousand recent fog and star clusters. He believed that the fog were objects within the Milky Way.

Charles Messier In addition, in 1781 a catalog of over 100 outstanding fogs produced. Messier was concerned about comet, so his list was quite a lot of Fuzzy objects that might possibly be confused with comets. He intended Comet hunter to avoid them because they didn’t move over the sky.

When further data got here up, the astronomers of the nineteenth century began to see that the fog was a mixed bag. Some were gaseous, constellating regions corresponding to that Orion Nebula or M42 – The forty second object in Messier's catalog – while other star clusters like that were Pleiades or M45.

A 3rd category – fog with a spiral structure – particularly fascinated astronomers. The Andromeda NebulaM31, was an excellent example. It is visible from a dark area for the mere eye.

https://www.youtube.com/watch?v=ALLQXSGYHNW

Astronomers were already speculated within the mid -18th century that some fog remedies could possibly be distant systems of stars or “island universes”, but there was there No data to support this hypothesis. Inseliniversen referred to the concept there could possibly be enormous star systems outside of the Milky Way – but astronomers now call these systems galaxies.

In 1920 the astronomers Harlow Shapley and Heber Curtis A held Great debate. Shapley argued that the spiral nebulae were small and milky, while Curtis took a more radical position that they were independent galaxies, extremely large and much.

At that point the controversy was not conclusive. Astronomers now know that galaxies are isolated star systems which can be much smaller than the space between them.

Hubble makes its name

Edwin Hubble Was young and bold. At the age of 30 he arrived at Mount Wilson Observatory in Southern California in good time to make use of the brand new hooker 100-inch telescopeAt that point the most important on the planet.

He began to take photography of the spiral fog. These glass panels recorded pictures of the night sky that covered a light-weight -sensitive emulsifier with their surface. The size of the telescope made it possible to take pictures of very weak objects, and its high -quality mirror made it possible for him to differentiate individual stars in some fogs.

Estimates of the distances There is a challenge in astronomy. Remember how difficult it’s to understand the removal of somebody who shows a flashlight on you on a dark night. There are galaxies in a really large collection of sizes and lots more and plenty. The measurement of the brightness or the apparent size of a galaxy just isn’t a superb guide to distance.

Hubble used a discovery of Henrietta Swan Leavitt 10 years earlier. She worked on Harvard College Observatory as “human computer”Measure the positions and brightness of hundreds of stars on photographic plates.

She was particularly concerned about CSPEID -VARIABLEThe stars are frequently pulsates, so that they turn out to be brighter and dimmer with a certain time. She found a relationship between her variation period or her pulse and her intrinsic brightness or luminosity.

As soon as you measure the period of a cepheid, you possibly can get the space from the sunshine appearance of using the one with the calculation reverse square law. The further the star is removed, the weaker it appears.

Hubble worked hard, recorded every clear night pictures of spiral nebulas and looked for the treacherous variations of Cepheid variables. By the top of 1924 he had found 12 Cepheids in M31. He calculated the removal of M31 as a tremendous 900,000 light years, although he underestimated his true distance – about 2.5 million light years – by not noticing it Two differing kinds by chespid variables.

His measurements marked the top of The big debate About the dimensions of the Milky Way and the character of the fog. Hubble wrote about his discovery to Harlow Shapley, who had argued that the Milky Way included the complete universe.

“Here is the letter that has destroyed my universe.” Shapley noticed.

Always looking forward to promoting, Hubble licked his discovery In the New York Times five weeks before a colleague presented his newspaper on the Astronomers annual meeting in Washington, DC

A growing universe of galaxies

But Hubble wasn't finished yet. His second major discovery also modified the understanding of the astronomers for the universe. When he distributed the sunshine from dozens of galaxies right into a spectrum that recorded the quantity of sunshine with every wavelength, he noticed that the sunshine was at all times moved to longer or redder wavelengths.

Light from the galaxy flows through a prism or reflected by A Flab In a telescope that captures the sunshine intensity from blue to red.

Astronomers call A shift to longer wavelengths a red shift.

It seemed that these red -released galaxies all remove from the Milky Way.

Hubble's results indicated that a galaxy was further away It moved away faster from the earth. Hubble received the lion's share of the loan for this discovery, however the Lowell Observatory astronomer Vesto SlippherWho noticed the identical phenomenon, but didn’t publish his data, also expected this result.

Hubble referred to galaxies Recession speedsOr speeds to maneuver away from the earth, but he Never found That they move away from the earth since the universe increases.

Belgian cosmologist and Catholic priest Georges Lemaitre made this connection by realizing that the speculation of General theory of relativity described an expanding universe. He realized that the space between the galaxies could cause the red shifts, which looks like they were further away from one another and from the earth.

Lemaitre was the primary to argue that the expansion during The Big Bang.

The NASA called its flagship world space observatory based on Hubble, and it was used to Galaxies have been studying for 35 years. Astronomers routinely observe galaxies which can be weaker and further away as galaxies that were observed within the Twenties. The James Webb Space Telescope has moved the envelope even further.

The Current record holder Is a galaxy in 34 billion light years that were seen only 200 million years after the large bang when the universe was 20 times smaller than today. Edwin Hubble could be amazed to see such progress.