Light travels incredibly fast.
300,
000 km per second.
Or at least it feels that way for us humans here on Earth.
Because the distances in space are so vast,
Light from the stars actually takes a significant amount of time to reach us.
So as you look up into the night sky,
You're actually seeing back in time.
Into the past.
On a very dark night,
The unaided eye can see a total of around 4000 stars.
How many can you see right now?
Most of the most obvious bright stars are between a few ten to a few thousand light years away.
Meaning the light has been travelling for a few decades to a few centuries or millennia to reach you.
So amongst all the stars you can see,
Find one.
And just watch as it twinkles.
Softly shifting in colour,
Shape,
Brightness.
Such a tiny point of light.
In all the vastness of the universe,
What are the chances that one beam of light from this star hits your eye at just this one point in time?
How does that feel?
The light you're seeing has travelled for all those years through space,
Only to pass through the Earth's atmosphere and enter your eye.
Right here.
Right now.
Our nearest neighbouring star is Alpha Centauri,
Which is visible from the southern hemisphere.
Light from this star takes about four years to reach us.
The brightest star in the sky is known as Sirius,
Visible in the northern hemisphere in the constellation of Canis Major,
The dog.
Light from Sirius takes about nine years to reach us.
From Polaris,
The north star,
In Ursa Major,
The lesser bear,
Light takes about four hundred years to reach us.
And from Deneb,
Which makes the tail of the swan in the constellation Cygnus,
It takes about one thousand six hundred years.
Take a moment to let your eyes wander across the night sky,
This vast window into the past,
Our cosmic time machine.
On these scales,
Your life,
Well all our lives,
Are but just a blink of an eye.
Consider all the things we get worried about,
We get stressed about,
We lose sleep over.
How do they feel when we consider the universe like this?
It's not to say that these things don't matter,
But it's just important sometimes to put them in perspective.
Laurean stress tend to make us a little bit tunnel visioned.
So how about right now,
Purposefully tuning into the periphery of your vision?
There's no need to move your eyes,
Just notice what you can see around the edges.
When we do this,
It's saying signal to the body that it's okay to relax,
It's okay to be calm.
The furthest object visible to the unaided eye is the Andromeda Galaxy.
This is a very faint smudge in the constellation Andromeda,
Visible to most people in the Northern Hemisphere.
Andromeda is the sister galaxy to the Milky Way.
It's about 2.
5 million light years away.
That means light has been traveling from this galaxy for two and a half million years to reach us.
If you can see Andromeda Galaxy,
Its light will have left just when the earliest humans began walking the Earth.
Isn't that incredible?
So when we're looking up,
We're looking into the past.
But this is actually only true on one level.
Those light rays that have been traveling through the universe for all those centuries know nothing of the history.
They arrived now and deliver their information now.
In fact,
All of history,
Past and future,
Actually only exists now.
And this is the now of you,
Right here,
Looking up at this beautiful starry night.
