LIGHT-YEAR AND YEARS
Light-year is the unit of measurement in Astronomy. As the distance between planets and stars are very vast, they could be measured in terms of light years. This is how the distance in space is calculated.
Lights travel at 300,000 km per second, from light-second to light-year. A light-second denotes to the travel of the light in one second, i.e. 299 million meters. And the light-year refers to the light travels in a year, i.e. 9.46 trillion km.
There is another way of calculating the distance. This is called Parsecs. It is 3.25 light years. A light year is equal to 0.3066 Parsecs. The astronomers can see the far flung galaxies with their powerful telescopes. The sun light takes just eight minutes to reach the earth!
Of all these stars in the Universe, star ‘Deneb’ is said to be about 1500 to 1800 light years away!
Year is the time taken by the earth to orbit around the Sun, once. It is known as the Gregorian calendar, the modified form of the Julian calendar introduced by Pope Gregory XIII in the year 1582. This is what we have been following since then. We have different periods of time in a year. Calendar year from January 1 to December 31, financial year from April 1 to March 31 and Academic year from June to April. Precisely, the earth takes 365.24219 days for one such orbit. It is called the ‘Solar’ year, too.
If so, why do we have 366 days in a leap year? The answer is to make up the loss of 0.24219 day; it is accumulated and added as one day extra. But planet Mercury has the shortest time in a year of just 88 days! And the planet with the longest period of time for a year is, Pluto. It takes about 249 earth’s years to travel once around the sun, because it is the farthest one from the sun. It is between 4730 to 7375 million km away. However, planet Venus’s year is almost closer to the earth: Just 225 days.