One light year is ……………. In vacuum in…………….. .

Answer

To solve the question "One light year is ……………. in vacuum in……………..", we need to understand what a light year represents.

### Step-by-Step Solution:

1. **Definition of a Light Year**:
A light year is defined as the distance that light travels in a vacuum in one Julian year.

2. **Understanding a Julian Year**:
A Julian year is approximately 365.25 days. This accounts for the leap year every four years.

3. **Distance Calculation**:
The speed of light in a vacuum is approximately \(3 \times 10^8\) meters per second. To find the distance light travels in one Julian year, we can use the formula:
\[ \text{Distance} = \text{Speed} \times \text{Time} \]

4. **Convert Time to Seconds**:
First, we need to convert 1 Julian year into seconds:
\[ 1 \text{ year} = 365.25 \text{ days} \times 24 \text{ hours/day} \times 60 \text{ minutes/hour} \times 60 \text{ seconds/minute} \]
\[ = 365.25 \times 24 \times 60 \times 60 \approx 31,557,600 \text{ seconds} \]

5. **Calculate Distance**:
Now, we can calculate the distance:
\[ \text{Distance} = 3 \times 10^8 \text{ m/s} \times 31,557,600 \text{ s} \approx 9.461 \times 10^{15} \text{ meters} \]

6. **Final Answer**:
Therefore, we can fill in the blanks:
"One light year is approximately \(9.461 \times 10^{15}\) meters in vacuum in one Julian year."

### Summary:
One light year is approximately \(9.461 \times 10^{15}\) meters in vacuum in one Julian year.

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