# How do I calculate light years to years?

• Kronos5253
In summary, the conversation revolved around the discovery of a super-Earth planet with liquid water 40 light years away and the question of how far into the past we are seeing the planet. Some formulas and calculators were shared to estimate the time it would take to travel to the planet based on acceleration, top speed, and coasting time. It was also noted that the question had changed from the original post.
Kronos5253
I have a question, sparked by http://http://www.cnn.com/2009/TECH/12/16/super.earth.discovery/index.html" article, so I figured this would be the best place to put this.

That is said to be 40 light years away... So if we're seeing a planet 2.7 times the size of Earth with liquid water on it, and it's 40 light years away, how do you calculate how far into the past we are seeing this planet?

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Kronos5253 said:
I have a question, sparked by http://http://www.cnn.com/2009/TECH/12/16/super.earth.discovery/index.html" article, so I figured this would be the best place to put this.

That is said to be 40 light years away... So if we're seeing a planet 2.7 times the size of Earth with liquid water on it, and it's 40 light years away, how do you calculate how far into the past we are seeing this planet?

If it is 40 light years away, then the light we see reveals the planet as it was 40 years ago.

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sylas said:
If it is 40 light years away, then the light we see reveals the planet as it was 40 years ago.

In terms of light years, yes... I basically mean 'Earth years'.. Meaning if we were to travel to that planet, how old would we be when we got there?

I tried finding a formula to figure that out, but I haven't really found anything.. So any help would be appreciated :)

Entirely depends on how fast you travel there. Need to know acceleration, top speed, coasting time and deceleration.

The more of your journey you spend at near c, and the closer you get to c, the shorter the duration. There is no limit in principle to how short the duration can be by maximizing these two factors.

In my http://www.davesbrain.ca/science/gliese/index.html" I used the distance of 22.6 ly and an acceleration/deceleration of 1g. The result was a 22.6ly journey with the crew experiencing a mere 6.1 years.

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Kronos5253 said:
In terms of light years, yes... I basically mean 'Earth years'.. Meaning if we were to travel to that planet, how old would we be when we got there?

I tried finding a formula to figure that out, but I haven't really found anything.. So any help would be appreciated :)
Here's the equation and a calculator that you can plug sample values into if you don't want to do the calculation yoursefl: http://www.1728.com/reltivty.htm

Note that this question is completely different than the one you asked in your first post.

russ_watters said:
Here's the equation and a calculator that you can plug sample values into if you don't want to do the calculation yoursefl: http://www.1728.com/reltivty.htm

Note that this question is completely different than the one you asked in your first post.

Yeah I realized that... And I realized that the answer to the first post is the answer I was looking for haha... I figured it would be a bigger number, but it makes sense to me.

Thanks for the answers though everyone :)

## 1. What is a light year?

A light year is a unit of measurement used in astronomy to measure distances in space. It is defined as the distance that light travels in one year, which is approximately 9.46 trillion kilometers or 5.88 trillion miles.

## 2. How do I calculate light years to years?

To calculate light years to years, you need to divide the distance in light years by the speed of light, which is approximately 9.46 trillion kilometers per year. This will give you the equivalent distance in years.

## 3. Can light years be converted to regular years?

Yes, light years can be converted to regular years by dividing the distance in light years by the speed of light. This will give you the equivalent distance in years.

## 4. Why do we use light years instead of regular years in astronomy?

We use light years instead of regular years in astronomy because it is a more convenient unit of measurement for distances in space. Since the distances in space are incredibly vast, using light years allows us to express these distances in a more manageable way.

## 5. Is a light year the same as a regular year?

No, a light year is not the same as a regular year. A light year is a unit of measurement for distance, while a regular year is a unit of measurement for time. They cannot be used interchangeably and have different conversion factors.

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