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• Continues from Walking the Earth

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When we stand on the Earth at the equator and look up up, we will see the Sun pass overhead once each day. It rises and sets because the Earth makes one rotation every day.

Looking from space, from above the North Pole, we would see that the Earth is about 12.7 thousand km across. This number is not the distance from one side of the equator to the other. Think of this measurement like holding a straight ruler up against a ball. Our eye, the ruler and the ball are all lined up. The ruler does not bend, our measurement is from one side of the ball to the other, looking by eye.

If our imaginary ruler were held up against the Earth, how long would it take us to walk the measurement of that ruler?

	12,700 km	The measurement of the face of the Earth.
x	1000s	Average walking speed (km/s)
=	12,700,000	The number of seconds to walk the face of the Earth
/	60	Number of seconds in a minute
=	211,666	The number of minutes to walk the face of the Earth
/	60	Number of minutes in an hour
=	3527	The number of hours to walk the face of the Earth
/	24	Number of hours in a day
=	146	The number of days to walk the face of the Earth

When the earth spins, it does not spin perfectly like a ball on a string. Instead, the Earth wobbles a little bit. This is the primary cause for our seasons.

The Earth rotates to the east at 465.11m/s or 1,174.396kmph. From above the North Pole looking down at the Earth we would see the Earth rotate counter-clockwise.

	465.11m/s	Speed of the earth’s rotation
/	1000	Number of metres in a kilometre
=	0.46511km/s	Speed of the earth’s rotation (km/s)
x	60	Number of seconds in a minute
=	27.9066km/min	Speed of the earth’s rotation (km/min)
x	60	Number of minutes in an hour
=	1,674.396km/h	Speed of the earth’s rotation (km/h)

The mid-latitudes of the U.S. and Europe rotate at at 1125 to 1450 km/h.

Moving from above the Earth to above the Sun, nearly 150 million kilometers away, we see that the Sun is almost 55 times larger at about 696 thousand km across. Like before, this measurement is by eye using our unbending ruler.

If our imaginary ruler were held up against the Sun, how long would it take us to walk the measurement of that ruler?

	696,000 km	The measurement of the face of the Sun.
x	1000s	Average walking speed (km/s)
=	696,000,000	The number of seconds to walk the face of the Sun
/	60	Number of seconds in a minute
=	11,600,000	The number of minutes to walk the face of the Sun
/	60	Number of minutes in an hour
=	193,333	The number of hours to walk the face of the Sun
/	24	Number of hours in a day
=	8055	The number of days to walk the face of the Sun
/	365.25	The average number of days in a year (remember Leap Years!)
=	22.05	The number of years to walk the face of the Sun

At 1,412 million billion km³ the Sun is over 1.3 million times the volume of earth. That means that if the Earth were a ball of clay, we could stuff 1.3 million Earth-sized balls of clay together to form a ball the size of the Sun. Throwing the Earth at the Sun would be like throwing a pebble into the ocean.

The Sun is so big and heavy that it contains 99.86% of our Solar system’s mass.

The Earth is in orbit at about 149.6 million kilometers away from the sun. We call this 1 Astronomical unit (AU) [ 1 ]. Although the Earth’s orbit is not a circle but is an ellipse, there is a defined way of determining a measurement in Astronomical Units (AUs).

How long would it take to walk one Astronomical Unit, the distance from the Earth to the Sun?

	1s to walk 1m
=	1,000s to walk 1,000m (1km)

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	149,600,000 km	The distance from the Earth to the Sun
x	1,000sec	The amount of time to walk one kilometer (at 1km/s)
=	149,600,000,000	The number of seconds to walk from the Earth to the Sun
/	60	The number of seconds in a minute
=	2,493,333,333.33	The number of minutes to walk from the Earth to the Sun
/	60	The number of minutes in an hour
=	41,555,555.55	The number of hours to walk from the Earth to the Sun
/	24	The number of hours in a day
=	1,731,481.48	The number of days to walk from the Earth to the Sun
/	365.2564	The number of mean solar days in 1 sidereal year
=	4,740.45	The number of years to walk from the Earth to the Sun
/	10	The number of years in a decade
=	474.04	The number of decades to walk from the Earth to the Sun
/	10	The number of decades in a century
=	47.40	The number of centuries to walk from the Earth to the Sun

If it takes us 1s to walk 1m, and it’s 149.6 million kilometers to the sun, it would take us over 47 centuries to walk to the Sun (1 AU away).

But how long would it take with our electric hovercar?

	149,600,000 km	The distance from the Earth to the Sun
/	100	The speed of our electric hovercar (km/h)
=	1,496,000	The number of hours to drive from the Earth to the Sun
/	24	The number of hours in a day
=	62,333	The number of days to drive from the Earth to the Sun
/	365.2564	The number of mean solar days in 1 sidereal year
=	170.66	The number of years to drive from the Earth to the Sun

Even with our electric hovercar that goes about 27 times faster than us, it would take us 170 years.

With a rocket or some greater form of science-fiction spacecraft propulsion it would still take some time. This is, of course, ignoring problems such as acceleration, g-force or even experienced gravity.

Spoiler

An interesting note is that because the Sun is sort of “on fire” and is burning its fuel off it is slowly decreasing in mass. Because it is decreasing in mass, its gravitational pull is decreasing and all of the objects in orbit around it are slowly pulling away. This will slowly change the measurement of AU over time.

From further away, we could see that our Sun has a number of bodies orbiting it.

A star which has planets is called a planetary system. The Sun (astronomical symbol ☉ also called Sol) is a spectral class G2 star which has 9 planets orbiting it [ 2 ].

1. Mercury (☿)
2. Venus (♀)
3. Earth (♁ also called Terra)
4. Mars (♂)
5. Jupiter (♃)
6. Saturn (♄)
7. Uranus (♅/)
8. Neptune (♆)

9. Pluto (♇)

   • Pluto was downvoted after the writing of this article. =(

Since the Earth is the third planet from our star, we are Sol-3. Aside from the main planets, there are many other objects in our Solar system.

We know that the Earth revolves around the Sun. From above the sun looking down at the entire solar system, we would see the earth rotate once around the sun each year along the ecliptic plane. The earth’s average orbital speed is over 100,000 km/h. Each orbit takes 365.2564 mean solar days (or 1 sidereal year).

Ignoring objects with extra-massive regular orbits, like Comet Halley, the furthest object is Pluto at 39.5 AU. Remember that 1 AU is the distance from the Earth to the Sun. So this is 5,909.2 million km.

	149,600,000 km	The distance from the Sun to the Earth (1 AU)
x	39.5 AU	The distance from the Sun to Pluto (AU)
=	5,909,200,000 km	The distance from the Sun to Pluto (km)
/	1,000,000
=	5,909 million km	The distance from the Sun to Pluto (millions of kilometers)

If the Sun, the Earth, and Pluto were lined up, how long would it take us to walk to Pluto?

	39.5 AU	The distance from the Sun to Pluto
-	1 AU	The distance from the Sun to the Earth
=	38.5 AU	The distance from the Earth to Pluto (when lined up)

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	4,740.45 years	The time to walk from the Earth to the Sun (1 AU distance)
x	38.5	The distance from the Earth to Pluto
=	182,507.32 years	The number of years to walk from the Earth to Pluto
/	100	The number of years in a century
=	1,825.07 centuries	The number of centuries to walk from the Earth to Pluto

It would take us well over 1,825.07 centuries to walk to Pluto.

	4,740.45 years	The time to walk from the Earth to the Sun (1 AU distance)
x	38.5	The distance from the Earth to Pluto
=	182,507.32 years	The number of years to walk from the Earth to Pluto
/	100	The number of years in a century
=	1,825.07 centuries	The number of centuries to walk from the Earth to Pluto

But how long would it take us to drive from the Earth to Pluto?

	170.66 years	The time to drive from the Earth to the Sun (1 AU distance)
x	38.5	The distance from the Earth to Pluto
=	6570.41 years	The number of years to drive from the Earth to Pluto
/	100	The number of years in a century
=	65.70 centuries	The number of centuries to drive from the Earth to Pluto

Even driving in our electric hovercar, it would take a long time to drive to the furthest object in our solar system. Obviously we need faster transportation to go any further.

Spoiler

Pluto has a moon which is almost as large as it. Pluto and its moon circle one another, but each face always points to the other. This means that we could make a ladder from one to the other!

Continues with The Nearest Interesting Thing.

TODO ∞

• Termination shock

Footnotes

1. Actually, the Earth is 1 ± 0.02 AU from the Sun, because of its elliptical orbit. [ ↩ ]
2. The number of planets in our solar system is contested. There are a number of bodies orbiting our sun, see List of solar system objects by radius and Candidate planets. [ ↩ ]