Parallax Flashcards
What is an Astronomical Unit (au)?
1 au = the average distance from the Earth to the Sun
1 au = 1.5 x 1011m
What is a light year (ly)?
1 ly = distance travelled by light in 1 year
1 ly = (3.00 x 108) x (365 x 24 x 60 x 60)
1ly = 9.46 x 1015m
What is a Parsec (pc)?
1 pc = the distance d for which 𝜃 = 1‘‘ when 𝑅 = 1 au
where 𝜃 is the angle adjacent to 𝑅
1 pc = 3.26 ly = 3.09 x 1016m
How many arcminutes (‘) are there in 1 degree (°) ?
60
How many arcseconds (‘‘) are there in one arcminute (‘)?
60
What is the small angle approximation for tan 𝜃?
tan 𝜃 ≈ 𝜃
(where 𝜃 is in radians)
What formula links the distance in parsecs to the observed parallax angle?
d = 1/p
where d is the distance in parsecs and p is the observed parallax angle in arcseconds