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----------------- 1785 - Earth from Space Station
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- How many times does the Earth rotate making a single orbit around the Sun?
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- That was a trick question. Only Turner and Nathan got it.
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- This picture is Earth from the International Space Station. The Earth spins on its axis below while the station orbits every 96 minutes. So day night on the station is far different than from Mother Earth.
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- How about how many days in a year?
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- Everyone knows there are 365 days in a year and a few know that every 4 years there are 366 days making it a Leap Year. So, a year on average must be:
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------------------------ Year = 365.25 days
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- Well that depends on how you measure it. The path that the Earth travels around the Sun is a near circle ( slightly elliptical but not much). If you measure 360 degrees of a full circle of the Eliptic, as the orbit is called you get:
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-------------------------- Year = 365.24219 days
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- Now, if you don’t measure 360 degrees from the Earth but you measure when the Earth’ s orbit returns to the same background of the farthest stars you get:
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---------------------- Year = 365.256363004 days
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- What if you just measure exactly 12 cycles of the phases f the Moon ( Lunar Cycles) you get:
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-----------------------Year = 354.37 days
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- The Moon’s orbit is not a perfect circle either. Like the Earth’s orbit that is an elliptical orbit meaning that at some times it is closer to the Sun and conversely sometimes farther away. Closest orbit is called the “ Perihelion”. Now the time for the Earth to return to same closest point your get:
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--------------------- Year = 365.259636 days
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- Ok, then there is the Moon eclipsing the Sun. Called the Lunar Node, or the Eclipse Year. The time for one Lunar Node it the next you get:
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----------------------- Year = 346.620075883 days
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- Ok, I give up. Let’s just average it all out and agree to make the year 365.25 days. That is close enough for government work. It is just politics.
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- Lunar years are easier to define since we only have one Moon. Note the number of decimal points on the above number. But, how confusing would it be on Mars that has 2 moons. It gets worse:
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------------------------ Mars = 2 moons
------------------------ Pluto = 5 moons
------------------------ Neptune = 14 moons
------------------------ Uranus = 27 moons
------------------------ Saturn = 62 moons
------------------------ Jupiter = 67 moons
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- It becomes more complicated calculating the days in a year living on those planets. Measured in Earth years you get:
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------------------------ Mars = 1.881 years
------------------------ Jupiter = 11.86 years
------------------------ Saturn = 29.42 years
------------------------ Uranus = 84.01 years
------------------------ Neptune = 164.8 years
------------------------ Pluto = 248 years
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- Ok I give up again. Get past Pluto into the Kuiper Belt and you get to a “year of years” to get around the Sun. It is past my bed time, Good night. Tomorrow is another day.
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