How big is the universe ... compared with a grain of sand?
Summary
TLDRThis script explores the vastness of the universe, challenging human comprehension. It discusses astronomical methods like Parallax and standard candles to measure distances to stars. The script introduces the light year as a unit for cosmic distances and explains how observing stars is like looking back in time. It highlights the Milky Way and Andromeda galaxy, emphasizing the universe's enormity with the Hubble telescope's view of thousands of galaxies in a tiny patch of sky. The script concludes with a metaphor comparing the size of the universe to grains of sand, emphasizing its immensity.
Takeaways
- 🌌 The universe is so vast that it's difficult for the human mind to comprehend its true size.
- 🔍 Astronomers use the Parallax technique to measure distances to nearby stars by observing their apparent shift in position against the background stars from different points in Earth's orbit.
- 🌟 Standard candles, stars with known intrinsic brightness, help astronomers calculate distances by comparing their apparent brightness to us.
- 🚀 Proxima Centauri, the nearest star to the Sun, is an incredible 40 trillion kilometers away from Earth.
- ⏱ A light year is a unit of distance that represents how far light travels in one year, which is about 9.46 trillion kilometers.
- 🕰 Looking at stars is like looking back in time; the light we see from the Sun is already 8 minutes old.
- 🌍 Our Sun is part of the Milky Way galaxy, which is just one of the countless galaxies in the universe.
- 🌌 The Andromeda galaxy, visible to the naked eye, is approximately 2.5 million light-years away, meaning its light has taken that long to reach us.
- 🔭 The Hubble telescope's deep field image revealed that every speck of light in the photo is a galaxy, indicating the vast number of galaxies in the universe.
- 🌠 The visible universe contains around 100 billion galaxies, each with about 100 billion stars, making the number of stars more than the grains of sand on Earth.
- 🌐 If the Earth were a grain of sand, the Milky Way galaxy would be a thousand times larger than Durham Cathedral, and the entire visible universe would be unimaginably vast.
Q & A
What is the human mind's capability in comprehending the vastness of the universe?
-The human mind struggles to comprehend the true immensity of the universe due to its vast and enormous size.
What is Parallax and how is it used to measure distances to stars?
-Parallax is a phenomenon where an object appears to shift position relative to a background when viewed from different angles. In astronomy, it's used to measure distances to stars by observing the apparent movement of a star against the background stars as Earth orbits the Sun.
How does the concept of 'standard candles' help in measuring astronomical distances?
-Standard candles are stars with known intrinsic brightness. By measuring their apparent brightness as seen from Earth, astronomers can calculate their distance using the inverse square law of light.
What is the nearest star to the Sun and how far is it from Earth?
-The nearest star to the Sun is Proxima Centauri, which is approximately 40 trillion kilometers or about 4.24 light-years away from Earth.
What is a light year and how is it used in astronomy?
-A light year is the distance that light travels in one year, approximately 9.46 trillion kilometers. It is used as a unit of measurement for vast distances in space.
Why does the speed of light have a significant impact on our perception of the universe?
-The speed of light impacts our perception of the universe because it determines how long it takes for light from distant objects to reach us. This means that when we look at distant stars or galaxies, we are effectively looking back in time.
How long does it take for light from the Sun to reach the Earth?
-It takes about 8 minutes for light from the Sun to reach the Earth.
What is the significance of the Andromeda galaxy in relation to Earth?
-The Andromeda galaxy is the farthest object visible to the naked eye and is another galaxy outside our Milky Way. The light from Andromeda takes about 2.5 million years to reach Earth.
What did the Hubble telescope reveal when it observed a seemingly ordinary patch of the night sky?
-The Hubble telescope revealed that every speck of light in the observed patch was a galaxy, indicating that there are approximately 10,000 galaxies in a patch of sky the size of a grain of sand held at arm's length.
How many galaxies and stars are estimated to be in the visible universe?
-The visible universe is estimated to contain around 100 billion galaxies, each with about 100 billion stars, making the total number of stars approximately 10,000 million million million.
How can the size of the universe be conceptualized in relation to familiar objects on Earth?
-If the Earth were a grain of sand, the solar system would be as big as Durham Cathedral, and the Milky Way galaxy would be a thousand times bigger. If the Milky Way were shrunk to the size of a grain of sand, the entire visible universe would be the size of Durham Cathedral.
Outlines
🌌 Understanding the Universe's Scale
The paragraph introduces the immensity of the universe, which is beyond human comprehension. It explains the use of parallax to measure distances to stars by observing their apparent shift in position against the background stars from different vantage points on Earth. Additionally, it mentions the concept of 'standard candles,' stars with known luminosity, to calculate distances based on their observed brightness. The nearest star, Proxima Centauri, is highlighted as an example, being 40 trillion kilometers away. The paragraph also introduces the light year as a unit of measurement for such vast cosmic distances, defined as the distance light travels in a year. It concludes with a discussion on how the speed of light affects our perception of stars, essentially allowing us to look back in time, and a brief on the Milky Way galaxy and other galaxies visible to the naked eye, like Andromeda, whose light has taken over 2.5 million years to reach us.
🌟 The Staggering Number of Stars in the Universe
This paragraph delves into the sheer number of stars in the visible universe, comparing it to the number of grains of sand on Earth to emphasize the scale. It explains that each of the estimated 100 billion galaxies contains about 100 billion stars, leading to a total of 10,000 million million million stars. The concept of light traveling for 13 billion years from the most distant galaxies is introduced, illustrating the age and size of the visible universe. The paragraph concludes with a thought experiment comparing the Earth to a grain of sand, and then scaling up to the solar system, the Milky Way, and finally the entire visible universe, to give a sense of the universe's vastness.
Mindmap
Keywords
💡Universe
💡Parallax
💡Standard Candles
💡Proxima Centauri
💡Light Year
💡Milky Way
💡Andromeda Galaxy
💡Hubble Telescope
💡Galaxy
💡Visible Universe
💡Neptune
Highlights
The human mind struggles to comprehend the vastness of the universe.
Astronomers use Parallax to measure distances to stars by observing apparent shifts in their positions.
Standard candles, stars with known brightness, help calculate distances based on their observed brightness.
Proxima Centauri, the nearest star to the Sun, is 40 trillion kilometers away.
Astronomers use light years, the distance light travels in a year, as a unit of measurement for vast cosmic distances.
The speed of light is approximately 300,000 kilometers per second.
Observing stars is like looking back in time, as the light we see has taken time to reach us.
The Milky Way is just one of many galaxies in the universe.
The Andromeda galaxy is the farthest object visible to the naked eye, with its light taking 2.5 million years to reach Earth.
Telescopes are metaphorically time machines, allowing us to see celestial objects as they were in the past.
The Hubble telescope revealed that a seemingly dark patch of sky contains thousands of galaxies.
The visible universe contains around 100 billion galaxies, each with around 100 billion stars.
There are more stars in the visible universe than grains of sand on Earth.
Light from the most distant galaxies has taken around 13 billion years to reach us.
The visible universe stretches about 13 billion light years from Earth.
An analogy compares the Earth to a grain of sand, with the solar system and galaxy scaled up accordingly to illustrate the universe's size.
The universe is incredibly large, with its size often being beyond human comprehension.
Transcripts
[Music]
you'll never ever get your head around
how big the universe is don't go there
it's just vast it's enormous there's no
way human mind I think can actually
comprehend the true immensity of the
universe we're happy with the size of an
elephant or the size of a tree or maybe
even the size of Durham
cathedral but I think if we go beyond
that then our brains just start to run
out a gas it may be difficult for our
brains to comprehend but that hasn't
stopped astronomers endeavoring to
measure the distance to the Stars One
technique is to use a phenomenon called
Parallax everybody can actually
experience Parallax for themselves if
you hold your thumb up and close one eye
you can see that your thumb appears to
be in a certain position relative to
something behind your thumb but then if
you open that eye and close the other
eye you'll see your thumb appears to
move relative to the object
behind the same thing happens when we
look at the stars when we look at a
relatively nearby star from the earth it
appears in a certain position relative
to the other background Stars 6 months
later when the earth is on the opposite
side of the Sun the same star will
appear in a different position relative
to the background like opening and
closing one eye then the other the star
appears to move and by measuring this
apparent Movement we can calculate the
true position of the
star an alternative method of
measurement is to use certain stars in
the sky known as standard
candles we know exactly how brightly
they shine if we can therefore measure
how bright they appear to us on Earth we
can calculate how far away they are the
dimmer they appear the further they are
from the earth so the nearest star to
the sun is Proxima centur and that it
turns out is 40 trillion kilm away
that's 40 million million kilomet away
from the earth such numbers start to
become
incomprehensible and that's why
astronomers have adopted an alternative
unit of measurement for such vast
distances the light year a light year is
the distance that light will travel in
one year if you imagine light moving
around the Earth in one second
so in that time light would travel
around the Earth over seven times so
that's fast speed of light is 300,000 km
a
second so one light here is about 9
million million
kilm the speed of light also leads to a
curious consequence when we stare at the
stars so the light from the sun takes 8
minutes to get to the Earth um that
Essen entally means we're looking into
the past we're looking back at the Sun
as it was 8 minutes ago if the sun was
to disappear right now we wouldn't know
for 8 minutes so a telescope if you like
is a time machine we're looking back in
time and the further the object is away
from us the further back in time we're
seeing it our sun like nearly all the
stars we can see with the naked eye sits
inside the Galaxy we call the Milky Way
but our galaxy is not alone in the
universe not everything you can see in
the night sky is actually in our galaxy
um it turns out that some of those faint
dots are in fact other galaxies the
furthest object you can see actually
with with the uned eye is another galaxy
called Andromeda the light from that
galaxy has taken something like two and
a qu million years to get to the Earth
so if you imagine if we reverse the
scenario and you're looking at the Earth
from Andromeda with a very powerful
telescope you'd see no signs of cities
no civilization no Great Wall of China
you might be lucky enough to see one or
two sort of early humans hunting around
on the African plains for their dinner
maybe astronomers have always wanted to
see further using bigger and better
telescopes to try and find out just how
many other galaxies are out
there until finally we pointed the
Hubble telescope at what at first
appeared to be a very dark and ordinary
patch of the night sky if you imagine
holding up your finger with a grain of
sand on it and looking at the patch of
sky that that grain of sand blocks out
that's the field that the telescope
zoomed in onto and what the telescope
saw was
incredible every single Speck of light
in this photo is a Galaxy 10,000
galaxies in a patch of Sky the size of a
grain of sand held at arms length if
this tiny patch of sky is like every
other then we can calculate how many
galaxies are out there the visible
Universe contains around 100 billion
galaxies each one of those galaxies
contains around about 100 billion stars
that means the visible Universe contains
something like 10,000 million million
million stars that means there are more
stars in the visible Universe than there
are grains of sand on the earth the
light from some of these most distant
galaxies has taken around 13 billion
years to get here that's light traveling
at 300,000 km a second the visible
Universe stretch is around 13 billion
light years from the earth so we've said
the universe is Big I'm going to try and
give you some idea how big imagine the
Earth as a grain of sand if that was the
case then our solar system out to the
orbit of the planet Neptune would be as
big as Durham
Cathedral so now let's imagine we take
our solar system and we shrink it down
to the size of this grain of sand then
our galaxy The Milky Way would be a
thousand times bigger bigger than this
[Music]
Cathedral so now we take the Milky Way
galaxy and shrink it down to the size of
the grain of sand the cathedral would be
the entire visible
Universe the universe is Big it's really
big
[Music]
[Music]
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