Astronomy Picture of the Week – The CMB

*opens door* *dusts off cobwebs*

Time to get this started back up, too. And I’m doing that with this ridiculously amazing image. Now… I absolutely had to start this series off with that incredible image of Saturn, but this honestly should have been the next one. Not making this the very next picture was a mistake. But I’m making up for that now…

This is it right here. The oldest light we can see. The baby visible universe. The best evidence for, and the afterglow of, the Big Bang. The Cosmic Microwave Background.

This image is compiled from data collected by PLANCK. If you click on it, it will download a high resolution, 20.70mb TIFF of this same image. Here’s a link to see WMAP’s image, compiled from nine years of WMAP Data.

The Cosmic Microwave Background, as seen by PLANCK.

The Cosmic Microwave Background, as seen by PLANCK.

It’s an incredible thing, really. This radiation is the result of the recombination event after the Big Bang, which happened when our visible pocket of the universe was around 379,000 years old. That makes the light from this event around 13,769,621,000 years old, give or take 59,000,000 years (note… our visible pocket of the universe is around 13,770,000,000 years old, give or take 59,000,000 years; that difference may seem large, but it’s actually only 4% of the total lifespan of our visible universe in years; basically, 59 million is a very tiny number compared to 13.77 billion).

It’s amazing to think about that fact… light is the fastest thing in our universe, but it doesn’t travel instantly. It travels at a fixed rate of 186,282 miles per second in a true vacuum. This means that, when you look up into the sky, you’re looking into the past. This is even true for objects close to us. We see the sun as it was 8 minutes and 19 seconds ago, and the moon as it was about 1 second ago. But you can take it even further, because even when you look at yourself in the mirror, you’re seeing yourself as you were less than a nanosecond ago.

This means that, because light travels at a fixed rate, we do, in fact, look into the past. We just don’t have any control over how far, and depending on how close the object your looking at is, it’s not very far into the past at all. On earth, it’s only ever some nanoseconds, or less, into the past. But look into space, and that visual trip to the past stretches from light-seconds to lightyears. It’s a testament to just how big our visible universe is that we need to use time to measure it’s size. And even with time, measuring the size of the universe is still hard to do because the universe is expanding. That said, estimates from 2015 put it at around 93 billion lightyears in diameter (putting the edge around 46.5 billion lightyears away from us) because of the expansion rate, which is why we can only see part of it… there’s a whole lot of light that hasn’t had time to reach us, and there’s even more light that probably never will.

This isn’t a tangent from the image, by the way. This is how the image above inspires me to think. This is why I am so in love with the universe, and with all the scientific fields dedicated to studying it. Reality is so fascinating, so wondrous, so incredible… you really don’t need the supernatural at all to still be in awe of everything we see around us.

Just look at space. Why would we ever need anything more?


As an addendum, I’ve always been curious as to how Creationists deal with the CMBR, so I decided to google it. The stuff I found is hilarious in just how bad it all is. I’ll use Do Not Link (except for the first link, which is to Quora), but here are some results:

Comment to Quora Question – If there was no Big Bang, as creationist[s] love to say, why is there Cosmic Background Radiation?

From Creationwiki


From the Institute for Creation Research

From Answers in Genesis

From their “journal”

Yup… it’s hilarious just how bad it all is. They’re floundering, really.


  1. Pierce R. Butler says

    If I sorta squint at that, I can make out a hint of the Americas just to the left of the center, and Europe/Africa off to the right -- though Asia seems displaced a bit southward, and apparently the Pacific still has Lemuria above water…

  2. Andrew G. says

    If you think that creationists have trouble with the CMB, you should see what the geocentrists make of it.

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