Posted on October 13, 2021
This is an update of my post published on October 13, 2010:
It was only later that we discovered the beauty and violence of the Whirlpool galaxy. On this day in 1773, when Charles Messier first spotted and labeled the galaxy Messier 51 (or M51), he was just cataloging a little blob of light in his telescopic view of the night sky.
Messier was a French astronomer and comet hunter. Comets often appear to our naked eyes or telescopes as fuzzy patches of light in the dark sky, but of course they only appear for a few days or months and then disappear again, as their long elliptical orbits only bring them near Earth once in a very long while.
The other fuzzy patches of light that we can see night after night, and year after year, are considered “permanent” objects in the night sky. Messier decided to create a catalog of such objects and their locations, so that astronomers wouldn't be confused by them when looking for comets.
These more permanent blurry spots of light are usually nebulae (clouds of glowing gas), galaxies (huge groups of billions or even trillions of stars that are gravitational bound together, usually in spiral or elliptical shapes), or globular clusters (spherical groups of thousands or millions of stars).
Discovering the beauty...
Better viewing of M51 with better, more advanced telescopes revealed that it has a small companion galaxy and that the original galaxy has a very tight spiral pattern. That's why it is called Whirlpool Galaxy.
Discovering the violence...
Evidence seems to indicate that the small companion galaxy ripped back and forth through the center of Whirlpool about 500 million years ago and then again around 50 million years ago.
Learn more...
Our own Milky Way galaxy is a spiral, also, but we can't see the spiral from our vantage point. We look at spiral-shaped galaxies far from home, such as this one - the Andromeda Galaxy - to see what our own galaxy might look like from different angles.
We can see the Whirlpool Galaxy from "above," and so we are really able to see the spiral pattern.
Make a glittery galaxy picture.
Here is the Whirlpool Galaxy with photos taken using different wavelengths of “light":
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the Whirlpool Galaxy in X-rays Did you know that what we call light is electromagnetic radiation, and that different wavelengths and frequencies of radiation behave quite differently? For example, visible light cannot penetrate our skin, but X-rays can. You are probably familiar with electromagnetic radiation that is too low frequency to be seen, called radio waves or infrared, and you have also heard of high-frequency waves such as X-rays and ultra-violet. |
Also on this date:
aka Unity Day
(Second Wednesday in October)
(Second full week of October)
(Wednesday of Earth Science Week)
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