October 13, 2010

Whirlpool Galaxy discovered—1773

It was only later that we discovered the beauty and violence of this galaxy. On this day in 1773, when Charles Messier first spotted and labeled it 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 of Andromeda Galaxy, to see what that home might look like from different angles.

We are seeing Whirlpool Galaxy from "above" and so really get to see the spiral pattern.

Check out the Hubble gallery of photos of the gorgeous Whirlpool Galaxy.

And here is the galaxy with photos taken using different wavelengths of “light.” 

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.

This photo above is the Whirlpool Galaxy in X-rays.

1 comment: