Every so often astronomers will publish photos taken with an astronomical

telescope and say that the object that they captured is so many billions of

light years away. But how can they know the distance of something from just

looking at it? Furthermore, astronomers claim that the universe is almost

14 billion years old, and how could they possibly know that? Well, there are answers to these questions,

and surprisingly, astronomical distance and the age of the universe are closely intertwined.

Learn more about astronomical distances in the age of the universe on this episode of Everything

Everywhere Daily. Book your ticket to happiness with Sun Express Airlines. So, In a previous episode I talked about radiometric dating and how researchers can determine

the age of plants and birds and rocks and things.

What all of those techniques have in common is that they use the known rate of decay of

radioactive elements as a type of clock to determine the age of something.

If you look at the original isotopes ratio to the element

it decays into, you can get an idea of how old something is. The key to this method is that you need

a sample of the thing you want to test.

But when it comes to astronomy, especially very distant objects,

we don't have any samples.

All we have are observations and measurements of light.

By a similar token, just because astronomers can see an

object, how can they tell how far away something is? As it turns out, the answer to the

age of the universe is tied up in the question of how distant

astronomical objects are. To get to the answer to these questions we need to climb

something called the Cosmic Distance Ladder. Basically there are different methods that can be used to determine

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