Light-year or lightyear (symbol: ly) is a unit of measurement of length, specifically the distance light travels in a vacuum in one year.
While there is no authoritative decision on which year is used, the International Astronomical Union (IAU) recommends the Julian year.
A light-year is equal to 9,460,730,472,580.8 km (about 9.461 Pm; 5,878,625,373,183.61 statute miles; about 63,240 astronomical units or about 0.3066 parsecs.
The exact length of the light-year depends on the length of the reference year used in the calculation, and there is no wide consensus on the reference to be used.
The figures above are based on a reference year of exactly 365.25 days (each of exactly 86,400 SI seconds).
A few examples of distances for light to travel are: Reflected sunlight from the Moon's surface takes 1.3 seconds to travel the 4.04 × 10-8 light years to Earth.
It takes 8.3 minutes for light to travel from the Sun to the Earth (a distance of 1.58 × 10-5 light-years).
The most distant space probe, Voyager 1, was 13 light hours (only 1.5 × 10-3 light years) away from Earth in September 2004.
It took Voyager 27 years to cover that distance.
The nearest known star (other than the Sun), Proxima Centauri is 4.22 light years away.
The center of our galaxy, the Milky Way, is about 26,000 light years away.
Answer:
Both plant and fungal cells have a cell wall. The main difference between the fungal cell wall and the plant cell wall is that the plant cell wall is made up of cellulose whereas the cell wall of fungal cells are made up of chitin. Along with cellulose, the plant cell wall also comprises of hemicellulose and pectin.
Answer:
C. All motion is relative to the frame of reference chosen for measurement
Explanation:
