01. light years, stars, parsecs

the universe

• everything we can touch, feel, sense, measure or detect - the known universe

solar system

• consists of the sun, planets & moons, asteroids, comets

milky way

• a spiral galaxy containing billions of stars, orbiting around a black hole in the centre of the galaxy

stars

• huge celestial bodies made of mostly hydrogen and helium

  • produce light and heat from the churning nuclear forges inside cores

light years

• astronomical distance

• distance light travels in one year

  • 9.4607 × 10¹² km

parallax

• the apparent motion of a star when viewed from different positions/at different times of the year

  • depends on motion of observer

parsec

• based off parallax

  • short for parallax second

• can be used to measure the distance between our sun and other stars

• distance from the sun to a star whose parallax angle is one second

  • (1/3600 of a degree)

• equal to 3.26 light years

calculating parsecs

divide by 3.26

parsecs to light years

multiple by 3.26