Profile
Settings
Refer your friends
Sign out
One light-year is defined as the distance a light beam travels in a year. It is used to communicate galactic distances. It is almost equal to 6 trillion miles (9.7 trillion km). According to the International Astronomical Union, a light-year is a distance travelled by light in a Julian year. The light-year unit first appeared after successfully measuring the distance to a star other than the Sun. The largest unit at that time was an astronomical unit, which is equal to the radius of the earth’s orbit, that is, 93 million miles.
Some additional information on light-year:
Since light-year is the distance that light travels in a year; therefore large distances, such as the distance between stars, are best expressed in light-years.
Light travels at a speed of around 300,000 kilometres per second. As a result, the Sun’s distance from the Earth is approximately eight light minutes (150,000,000 kilometers).
Proxima Centauri is the next closest star from Earth. Alpha Centauri is approximately 4.3 light-years away (40,000,000,000,000 km).
It was invented by Friedrich Wilhelm Bessel. He was the first to use the light-year as a unit of measurement in astronomy. The distance that light travels in one year is almost equal to 9.4607 × 1012 km.
As we know that distance = r × t
= (speed of light) × (one year)
d = c.t
Time duration of Earth’s year = 365 days
= 365 × 24 hours
= 365 × 24 × 60 minutes
= 365 × 24 × 60 × 60 seconds
= 31536000 seconds
= 3.1536 × 107 seconds
Also, speed of light = 3 × 108 metre/seconds
Therefore, Distance = (speed of light) × (one year)
= 3.1536 × 107 seconds × 3 × 108metre/seconds
= 9.47 × 1012 km
In astronomical units, 1 light year = 63241 au
Dimensional formula
The physical quantity’s dimensions are the powers to which the fundamental quantities are elevated to represent that amount. The dimensional formula of any physical quantity is an equation that explains how and which of the base quantities are contained in that amount. It is written by enclosing the symbols representing base amounts in square brackets with the corresponding power.
E.g., the Dimension formula of Displacement is: [L]
In general, the total height of a wave is called its Amplitude. According to Physics, Amplitude refers to the maximum dispersion of a point on a vibrating subject from its equilibrium point.
As a result, the amplitude of a pendulum is one-half of the distance travelled by the bob as it moves from one side to the other. This is because vibrating sources produce waves, and their amplitude is proportional to the source’s amplitude.
Dimensional formula of a light-year
We know that light-year is the distance that light travels in a year, So basically, it’s one kind of distance. So, the Dimensional Formula of a Light Year will be the same as the Dimensional Formula of distance.
Dimensional Formula of distance =[ M0 L1 T-1]
Therefore Dimensional Formula of a Light Year = [ M0 L1 T-1]
Conclusion
One light-year is defined as the distance travelled by the light beam in a year. It is used to express astronomical distances. The largest unit at that time was an astronomical unit, which is equal to the radius of earth’s orbit, that is, 93 million miles. The distance that light goes in one year is practically equivalent to 9.4607 × 1012. In astronomical units, one light-year = 63241 au. The unit most commonly used in professional astronomy is the Parsec. It is almost equal to 3.26 light-years.
