# Astronomical distances

- Created by: Percy96
- Created on: 02-09-13 16:45

First 336 words of the document:

Astronomical Distances

1 astronomical unit (AU) is equal to 1.496x1011m

One astronomical unit is the mean distance from the centre of the Earth to the centre of the Sun. It is

used whilst studying the Solar System. The Earth's orbit is elliptical so at the start of the year the

distance between the Earth and the sun is 1.471x1011 whereas later on in the year it is slightly further

away, 1.521x1011. The average of these results is 1.496x1011m.

1 Light Year is equal to 9.461x1015

The light year is the distance light will travel through a vacuum in one year. It is not measured in time it

is measured in distance. To work out 1 light year you multiply the number of days in a year, 365.25

by how many seconds there are in a day x24x60x60, and then times that by the speed of light.

X2.9979x108. It's just Distance=Speed X Time.

The Parsec

To work out the distances between stars a triangulation method was used. The length of B

was taken and the angle A and C were measured. This enabled the distances of C and A to be

measured. However both angles A and C are always 900 instead a length of two astronomical

units are used. (2AU) The angles will always be small.

You then get an equation of sin=2AU/X and the distance (X) = 2AU/ where the angle is

measured in Radians.

The Parsec is a unit related directly to this method of Astronomical distances. It is a

shortening of parallax of one second. It is the distance away an object must be to have a

parallax of one arc second when observed.

An arc second is 3600th of a degree

An arc minute is 60th of a degree

1 Parsec (1pc)= 2.1x105 AU

1 Parsec (1pc)= 3.3 light years

1 Parsec (1pc)= 3.1x1012m

## Comments

No comments have yet been made