Posts Tagged ‘Size of Solar System’

Our sun has a diameter of about 1.3 million kilometers and it’s about 150 million kilometers away. Let’s say we shrink the size of the sun down to the size of a human red blood cell. That’s about 7 micrometers. It would be a really, really tiny speck, not visible with the human eye. If the sun were that small, the entire solar system would have a diameter of about 5 centimeters, about the size of a tangerine. However, the solar system isn’t really a ball, like a tangerine. All the planets orbit around the sun on one plane. So it would be better to describe the solar system as a thin disk the size of a tangerine. Even that’s not a good description. In the center is the sun, with 99.9 percent of all the mass in the solar system. Remember, the sun is the size of a red blood cell. You can’t even see it. The eight major planets are fantastically smaller still. And those eight planets make up the tangerine-sized disk.

Enough about the solar system and tangerines. Now that we have a sense for the solar system made that small, how far away do you think the nearest star system is? That would be Alpha and Proxima Centauri, which is about 4.3 light years away from here.

The answer is 219 meters. That’s a little bit more than the length of two football fields. Ok, let’s picture that. The sun is an invisible speck the size of a red blood cell with the solar system the size of a tangerine. Then the nearest star and its planets is another tangerine more than two football fields away. Just imagine the massive amount of empty space in all directions, left, right, forward, back, up down of empty space, and then another tangerine-sized star system.

Now let’s visualize the nearest stars to our sun. It turns out that there are only about 77 stars within a sphere of 33 light years diameter around the sun. There are a few prominent stars among those 77, like Alpha Centauri, Sirius and Procyon, the brightest of the bunch. Many of the 77 are not even visible with the naked eye. Regardless, those are the 77 nearest stars. How big do you think a 33 light year bubble around us would be, if our solar system were the size of a tangerine? It would be about 1,680 meters. That just a bit more than a mile. So picture a bubble a mile across in all directions, with the solar system in the center, the size of a tangerine. Inside of that one-mile bubble in space, there are only 77 other star systems, 77 tangerines, floating around. And that’s our close neighborhood of only 16.5 light years on all directions.

Our Milky Way Galaxy is a disk of about 100 billion stars. The disk has a rough diameter of 100,000 light years. If our solar system is the size of a tangerine, then the Milky Way is about 5,000 kilometers across (or about 3,000 miles), or roughly the size of the continental United States. So picture yourself walking around the country and encountering these little solar system disks of 5 centimeters across spaced out every two football fields in all directions, and you get a sense of how wide open and empty our galaxy is.

And that’s just ours. Recent estimates are that there may be a trillion, that’s a million million, galaxies in our universe.

The world is a very large and very empty place.


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Moon one Pixel

Picture Credit: http://www.joshworth.com

If you ever want to visualize the incredible size of just our solar system, and how it is almost completely empty, go to this website by Josh Worth.

On that site you can scroll from the sun to the various planets, and as you scroll, you “feel” how small the planets are and how far they are away. If the moon were the size of a pixel, as seen in the picture above, Earth would a tiny dot of a few pixels and about 35 millimeters away from the moon.

Pluto is smaller than the moon. The moon has a diameter of 3,474 km, and Pluto only 2,368 km. It’s only 18% the moon’s mass. So it would be smaller than a pixel, and could not even be seen on this scale.

However, on this scale, it would still be about 685 meters away from this point. That’s about a third of a mile or the length of about seven football fields.

So, if the Earth were the size of this dot on this picture, then Pluto would be a speck of dust a third of a mile away.

The New Horizons spacecraft left Earth in January 2006 and has traveled more than eight years. It’s the fastest human-made object ever, traveling about 100 times faster than a modern jetliner. And it has been on the way for eight years leaving that blue speck on the screen aiming for that speck of dust 685 meters away.

And it’s going to hit it three days from now.


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