SPACE — When you think about astronomy, or when you look up into the night sky – the twinkling stars, and our beautiful moon – glimpses of distance come to mind. How far are these space objects from where we look, or from our beloved globe?
The answer to that question is quite short; FAR, far away. For example, the closest star to our sun, Proxima Centauri, is 4.2 light years away. The number 4.2 may sound simplistic, but since it’s a measurement of light years, it deserves more explanation. How many miles/kilometers is 4.2 light years, or for short, 1 light year is how many kilometers?
Well, Light years are not what they sound like. It is a measure of distance and not a measure of time. One light year is the distance traveled by a beam of light in one Earth year. This means that the light we see from the star Proxima Centauri has traveled more than 4 light years to reach us.
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The speed of light is constant throughout the universe and is known with high precision. In a vacuum, light travels at 670,616,629 mph (1,079,252,849 km/h). To find the distance of one light year, multiply that speed by the number of hours in a year (8,766 hours). The result: One light year is equal to 5,878,625,370,000 miles or 9.5 trillion km.
At first glance, that may seem like an enormous distance, but on the cosmic immense scale, that length is insignificant. One estimate puts the diameter of the universe at 28 billion light years. If we convert it to kilometers, then the number will be 28.000.000.000.000 x 9,500,000,000,000 = try to calculate the result yourself.
Why use Light Years?
On the scale of the universe, measuring distances in miles or kilometers as above is impractical given the enormous numbers. It’s much easier for astronomers to measure a star’s distance from us in the time it takes for light to travel that distance. So, Proxima Centauri which is 4.2 light years away, using kilometers will be 4.2 x 9,500,000,000,000 km.
In our cosmic neighborhood alone, the closest star-forming region to us, the Orion Nebula, is 7,861 miles away.000.000.000.000 miles away and if expressed in light years it becomes more efficient; 1,300 light years. The center of our Milky Way galaxy is about 27,000 light years away.
The closest spiral galaxy to us, the Andromeda galaxy, is 2.5 million light years away. Some of the most distant galaxies we can see are billions of light years from us. The galaxy GN-z11 is considered to be the most distant galaxy that can be detected from Earth, which is at a distance of 13.4 billion light years. Imagine if it was written in miles or kilometers.
Like degrees, light years can also be broken down into smaller units of light hours, light minutes, or light seconds. For example, the sun is more than 8 light minutes away from Earth, while the moon is only one light second away. Scientists use this term when talking about communication with satellites or space explorers. Due to the limited speed of light, it will take more than 20 minutes to send a signal to the Curiosity rover on Mars.
Measuring in light years also allows astronomers to determine how far in time they are looking. Because light takes time to reach our eyes, everything we see in the night sky doesn’t actually happen right away. In other words, when you observe something 1 light year away, you see it as it did exactly one year ago. We see the Andromeda galaxy as it appeared 2.5 million years ago. The most distant object we can see, the cosmic microwave background, is also our oldest view of the universe, occurring just after the Big Bang about 13.8 billion years ago.
Alternatives to Light Years
Astronomers also use parsecs as an alternative to light years. Short for parallax-second, parsec comes from the use of triangulation to determine the distance to stars. To be more specific, this is the distance to a star whose position appears to shift by 1 arcsecond (1/3,600 degree) in the sky after Earth has orbited halfway around the sun. One second of arc is equal to 3.26 light years.
Whether it’s light years or parsecs, astronomers will continue to use both to measure distances in our vast, even vast, universe. However, if you have another input for describing the distances of objects in the universe, it’s fine to suggest it to astronomers. Source: Space.com
Also read:
How Much Are NASA Astronauts Salary? Can Buy a Car Every Month
How Long Does It Take to Get to Jupiter?
How Do We Know How Old the Earth is?
How Long Does it Take Humans to Explore Other Planets?
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2023-04-29 13:04:16
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