Looking Up: The Universe... Big, Isn't It?

Nov 19, 2018

A diagram showing the brightest galaxies within 20 million light years of the Milky Way, as seen from above. The largest galaxies, here shown in yellow at different points around the dotted line, make up the ‘Council of Giants’.
Credit Marshall McCall/York University / earthsky.org

This week on Looking Up, Tammy Terwelp, the General Manager of 91.5 KRCC, is the guest host. She gives us an idea of just how big the universe is.

We’ve been airing the weekly Looking Up show for just under 4 years now, and during that time, listeners have heard Hal talk about lots of different and amazing things in the Colorado sky. We’ve learned about planets, galaxies, comets, stars, and more. But one thing I’ve wondered about is just how much stuff is out there? In other words, how big is big?

As it turns out, the universe is pretty big and there’s lots of stuff in it. So how do you get your mind around these big numbers. Here’s one way: think about every beach on the Earth and every grain of sand on those beaches. Next think about every desert and every grain of sand in those deserts. Now add the two together and think about every grain of sand on the entire Earth. Well, there are more stars in our Milky Way galaxy than there are grains of sand on Earth. That’s a lot of stars, and the Milky Way is far from the biggest galaxy, with only about 200 – 300 billion stars. Our neighbor, the Andromeda Galaxy, has upwards of 1 trillion stars in it! And a word of warning! In about 2-3 billion years the Milky Way galaxy, and the Andromeda Galaxy, will collide! The stars are far enough apart that there likely won’t be any actual collisions, but the galaxies will merge into a giant super-galaxy. So if you are looking up in about 3 billion years, you’ll see wonders beyond words. 

NASA timeline of the universe
Credit nasa.gov

If you’d like to take a closer look the wonderful and amazing things in the sky, please visit csastro.org for a link to information on monthly meetings and free public star parties.