<p>The key to this kind of comparisons is to get a ratio. How much bigger is one number than the other?</p>

<p>From Buenos Aires to Los Angeles, there are nearly 10,000km. The size of a grain of sand varies a lot, but let's say it's a millimetre in diameter.</p>

<p>That's 4 orders of magnitude in the numbers themselves, then three orders of magnitude from there being a thousand metres in a kilometre, and three more from there being a thousand millimetres in a metre.</p>

<p><span class="math-container">$=10^{10}$</span></p>

<p>This is how much larger the LA - Buenos Aires distance is than the diameter of that grain of sand. It is <em>also</em> how much larger the distance out in the universe is compared to the diameter of the Earth.</p>

<p>The Earth's diameter is a bit more than ten thousand kilometres, so after multiplication, we will end up with about <span class="math-container">$\approx 10^{14}km$</span>. A light year is about <span class="math-container">$10^{13}km$</span>, so we get out to the handful of closest stars.</p>

CC BY-SA 4.0
2020-02-09T17:26:56.627Z
From that, the 1mm sand would be "coarse sand"
SE - stop firing the good guys
CC BY-SA 4.0
2020-02-08T11:25:21.720Z
2020-02-08T11:25:21.720Z
SE - stop firing the good guys
<p>If Earth was a grain of sand in Buenos Aires</p>

<p><a href="https://i.sstatic.net/2GrPM.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/2GrPM.png" alt="enter image description here"></a></p>

<p>in what point in this observable universe map would be LA be?</p>

<p><a href="https://i.sstatic.net/5eMUo.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/5eMUo.jpg" alt="enter image description here"></a></p>

CC BY-SA 4.0
2020-02-07T23:22:35.847Z
Of order only ten light years away.
uhoh
CC BY-SA 4.0
2020-02-12T10:37:22.207Z
LA and BA both at the center. I don't get the question, to be honest.
Alchimista
<earth><distances><observable-universe>
Earth as a grain of sand
Alex
# Earth as a grain of sand

(Asked by: username_0 on 2020-02-07)

If Earth was a grain of sand in Buenos Aires

[![enter image description here](https://i.sstatic.net/2GrPM.png)](https://i.sstatic.net/2GrPM.png)

in what point in this observable universe map would be LA be?

[![enter image description here](https://i.sstatic.net/5eMUo.jpg)](https://i.sstatic.net/5eMUo.jpg)

**Tags:** earth, distances, observable-universe

> **Comments:**
> **username_1**: Of order only ten light years away.  
> **username_2**: LA and BA both at the center. I don't get the question, to be honest.  

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## 1 answers

### Answer by username_3 on 2020-02-08. Score: 3

The key to this kind of comparisons is to get a ratio. How much bigger is one number than the other?

From Buenos Aires to Los Angeles, there are nearly 10,000km. The size of a grain of sand varies a lot, but let's say it's a millimetre in diameter.

That's 4 orders of magnitude in the numbers themselves, then three orders of magnitude from there being a thousand metres in a kilometre, and three more from there being a thousand millimetres in a metre.

$=10^{10}$

This is how much larger the LA - Buenos Aires distance is than the diameter of that grain of sand. It is *also* how much larger the distance out in the universe is compared to the diameter of the Earth.

The Earth's diameter is a bit more than ten thousand kilometres, so after multiplication, we will end up with about $\approx 10^{14}km$. A light year is about $10^{13}km$, so we get out to the handful of closest stars.

> **Comments:**
> **username_3**: From that, the 1mm sand would be "coarse sand"  

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