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Beyond the Milky Way — a game-changing discovery

As I’ve noted elsewhere (Beyond the infinity of black holes), it wasn’t long ago — maybe a 100 years or so, that our view of the cosmos was much more circumscribed. Those who studied cosmology — physicists, astronomers, et al, viewed our cosmos in a much different way, at a much different scale — basically an island universe: Earth, the solar system and the Milky Way. We existed in a galaxy, but a singular one.

Now, almost one hundred years later, it is difficult to fully appreciate how much our picture of the universe has changed in the span of a single human lifetime. As far as the scientific community in 1917 was concerned, the universe was static and eternal, and consisted of a single galaxy, our Milky Way, surrounded by a vast, infinite, dark, and empty space. This is, after all, what you would guess by looking up at the night sky with your eyes, or with a small telescope, and at the time there was little reason to suspect otherwise. — Krauss, Lawrence. A Universe from Nothing: Why There Is Something Rather than Nothing (pp. 1-2). Atria Books. Kindle Edition.

The game-changing discovery was highlighted back in 2011 by this Space.com article “Star That Changed the Universe Shines in Hubble Photo” (May 23, 2011).

In homage to its namesake, the Hubble Space Telescope recently photographed a star that astronomer Edwin Hubble observed in 1923, changing the course of astronomy forever.

The star is a variable star that pulses brighter and dimmer in a regular pattern, which allowed scientists to determine its distance, suggesting for the first time that other galaxies exist beyond our own Milky Way.

“I would argue this is the single most important object in the history of cosmology,” said astronomer David Soderblom of the Space Telescope Science Institute in Baltimore, Md., who proposed pointing the Hubble Space Telescope at the star.

Can you say Cepheid variable?

When I get bogged down in the 10^-n scale of things, a reminder about standard candles at the other end of the scale of things helps restore my perspective on how science works — that, at its best, science moves us beyond circumscribed views.

 

One thought on “Beyond the Milky Way — a game-changing discovery

  1. January 12, 2018, Space.com: “Whirlpool Galaxy: Exploding With Supernovas.”

    M51 was first catalogued by Charles Messier in 1773 while the astronomer was plotting objects in the sky that could confuse comet-hunters. “M51” is a reference to “Messier 51,” one of about 110 entries now plotted in his Catalogue of Nebulas and Star Clusters. …

    It would take about 70 years to learn more about the fuzzy object’s structure, however. It was first discerned by William Parsons, using a 72-inch reflector telescope in 1845. “His drawing of the spiral galaxy M51 is a classic work of mid-19th-century astronomy,” said Encyclopedia Britannica of Parsons’ observations.

    Parsons’ discovery was the first so-called “spiral nebula” ever discovered, and in the five years following he found 14 more of these objects, according to the STScI. It was unclear for decades if these objects were a part of the Milky Way Galaxy or things that were independent of that.

    It wasn’t until Edwin Hubble used Cepheid variable stars to chart cosmic distances in M31 (the Andromeda Galaxy) in the 1920s that astronomers understood they were actually distant galaxies.

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