# Can someone help me understand "space years" better?

I created a role-playing community that takes place in outer space, much like Ender s Game and Star Trek. Right now, there are 3 locations; Earth, Mars, and a space station that stays in the same place directly between the two planets orbital paths. If the space station does a full rotation every 48 hours, how many Earth Years would it have taken if someone s character lived 20 years on the space station? Right now, we have it explained that the space station is stationary, mindlessly floating in the same spot for all that time. However, we might change it since we need for it to have easy access to both planets (minus the warp-speed theory.)

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• 1 year ago

A year is the time for one orbit around the Sun. Your space station's year would be about 1.42 Earth years.

A person spending 20 Earth years on the station would have been there for 14.1 space station years.

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For any planet in our solar system (real, hypothetical, or any object in orbit around the Sun), the cube of the semi-major axis distance from the Sun measured in astronomical units (AU), is equal to the square of the planet's orbital period measured in Earth years.

1. Cube the distance in AU.

2. Find the square root of that result. It will be the orbital period in Earth years.

• Zardoz
Lv 7
1 year ago

Use a highly elliptical orbit (called a Hohmann Transfer Ellipse) instead of a mid point orbit. It would be great for supply shipments; whereas, a mid point orbit would have no practical advantages whatsoever.

Source(s): [n] = 10ⁿ
• Amy
Lv 7
1 year ago

A year is the amount of time it takes for a planet to travel all the way around the Sun.

Earth makes approximately two full circles around the sun in the same time that Mars makes one circle around the sun, so a Mars year is approximately two Earth years.

Because they move at different speeds, sometimes the two planets are near each other, and sometimes they are on opposite sides of the Sun. So where do you want your space station to be?

In a circular or elliptical orbit, the planet's momentum makes the sun's gravity swing the planet around the sun instead of falling straight down into the sun.

The difference between Earth and Mars year lengths isn't random. For any particular distance from the Sun, a planet needs to move at a particular speed in order to match the gravitational force. Too slow and we'd fall into the Sun; too fast and we'd fly away. The further a planet is from the Sun, the slower it has to move.

From a practical standpoint, the station should also be in a fixed orbit around the sun.

Being "stationary" relative to the sun would require literal tons of fuel to oppose the sun's gravity, just as an object hovering in the air needs fuel to hold it up against Earth's gravity. Likewise, the position of "exactly halfway between Earth and Mars" is a complicated pattern that would need fuel to maintain. Watch the red line in this graphic: https://www.popularmechanics.com/space/solar-syste...

If the station's orbit is between Earth's and Mars's, then its year length is between Earth's and Mars's - somewhere around 500 days.

As you can see in that article, in order to minimize distance to both Earth and Mars, the best place to orbit might be somewhere close to the Sun like Mercury. In that case it would have a very short year (Mercury's is 88 days). Of course, being close to the Sun creates other problems.

If you want to make the math a little easier, you could put the station at the same distance as Earth, someplace else on our orbital circle. It would still sometimes be inconvenient to get to from Mars, but the calendar could match Earth's.