Correct Answer - Option 2 : Both 1 and 3
Parsec (parallactic second):
- It is the largest practical unit of distance used in astronomy.
- It is defined as the distance at which an arc of the length of 1 astronomical unit subtends an angle of 1 second of arc.
1 parsec = 3.08 × 1016 m
- It is the distance travelled by light in a vacuum in one year.
- A light-year is used in astronomy to measure the distances of nearby stars.
1 light-year = 1ly = 9.467 × 1015 m
Parsec: It is a unit of length used to measure the large distances to astronomical objects outside the solar system
Second: It is the standard international (SI) unit of time
Year: It is also a unit of time
1 year = 365 days
1 day = 48 hours
1 hours = 3600 seconds
- From the above discussion, it is clear that Parsec and Light year are not units of time. Hence, option (2) is correct.