17 December 2010

## The Scale of The Universe

Posted by Dan Satterfield

Consider the dot at the end of this sentence.

Imagine it is on a printed page instead of your computer. If it were, it would contain around 100 billion atoms of carbon. If you wanted to see those jiggling atoms with your own eye, you would have to enlarge that do to the size of 100 meters. About as big as a football (Euro or American) field.

You would then be able to see the individual atoms of carbon, but to see the nucleus of that carbon atom, you would have to enlarge the dot much more! You would need to stretch it until one edge was at the North Pole and the other at the South Pole! To see the two up and one down quarks inside the protons in that carbon atom, you’ll need to enlarge the dot a bit more. Stretch it to the Moon and then go another 20 times further out.

The building blocks of the universe are unimaginably tiny.

Yet the Universe itself is unimaginably vast.

Voayger has reached thepoint where the interstellar flow of particles from the stars is meeting the solar wind from our own sun. It's reached the edge of the influence of our tiny star. Click the image for more on Voyager.

It was announced this week at the AGU conference in San Francisco that Voyager 1 is no longer feeling the solar wind. The stream of atomic particles from our sun has dropped to zero.

Astronomer Phil Plait put it best when he wrote on his blog that Voyager no longer has the wind at it’s back. Voyager is now 116 astronomical units from the Sun. The most distant object crafted by the hand of the highest order primate species on tiny Earth.

Put a soccer ball on the ground and walk 1 meter away. Put a tiny piece of gravel down. That is Earth. Go 5 meters away from the ball and put a large marble down. That is Jupiter. Now go 40 meters out and put a speck of dirt just visible down on a leaf. That is Pluto.

Keep walking until you are 116 meters away. That’s where Voyager is. In a few years it will pass into interstellar space. Humans will colonise the stars before it reaches one.

We hope…

As Sagan would put it: To Voyager, Our sun is now just a bright star in the great cosmic dark now.

It takes a radio signal about 8 minutes to travel from the Sun to Earth. That is one astronomical unit. I’ll let you figure out how long it takes to send a command to Voyager at 116 AU.

There is a superb web site that has the scale of the Universe for you to explore. I love this site and can’t stop visiting it!

Click the image below and check it out.

The description of the size of a carbon atom is from PARTICLE PHYSICS A Short Introduction by Frank Close. Highly recommended.