Western Slope Skies - The Size of the Solar System

Nov 4, 2016

As humans on Earth, it’s hard to grasp how vast the Universe is, starting with our own Solar System.  To us, our Solar System seems like a big place.

The Sun is in the middle with the planets orbiting around it, but the true size of the Solar System is defined by the reach of its gravity; or how far away an object can be  and still orbit the Sun.  Beyond the planets is the Kuiper Belt of small icy and rocky bodies, and the Oort Cloud, an extended shell of icy objects that exists at the outermost reaches of the Sun’s gravity.

The Sun’s gravity dominates local space out to a distance of about 2 light-years, or almost half the distance from the Sun to the nearest star, Proxima Centauri

How do we get our head around these distances? One way is to try to illustrate them in terms we can relate to.

From our house north of Cedaredge, it takes us 50 minutes to drive the 36 miles to the KVNF studio in Paonia.  It takes us 4 ½ hours to drive to Denver.

Hypothetically, if we could drive all the way to Pluto, it would take more than 6,000 years to make the trip, and 19 million years to complete the journey to the edge of the Solar System. Now, we don’t drive over the speed limit, but even NASA’s New Horizons spacecraft, one of the fastest probes ever launched from Earth would need 37,000 years to make the trip.

Another comparison that some of us can relate to… football.

If the Sun were the diameter  of a grapefruit, and in relation, the Earth the size of a poppy seed, the Broncos would need a “second and goal” of 11 yards to run a touchdown from the Sun to the Earth.  If Pluto was a speck of pepper, it would be a run of over 4-½ football field-lengths away from the Sun.  And, in keeping with the analogy of the Sun as a grapefruit, Proxima Centauri, that nearest star, would be a road trip from Denver to play the Patriots in Foxborough, MA.

So, you are right; the Solar System is a big place - at least to us.

Western Slope Skies is produced by members of the Black Canyon Astronomical Society.  This episode was written & voiced by Joyce Tanihara.