aberration of starlight

Click a letter for the index

Or search the encyclopaedia:

 

 

Go

 

Click image to enlarge
Apparent displacement of a star from its true position, due to the combined effects of the speed of light and the speed of the Earth in orbit around the Sun (about 30 kps/18.5 mps).

During a year the apparent position of a star describes a curve around its true position. This curve is an ellipse except when the star lies on the ecliptic (when it is a line along which the star appears to move backwards and forwards) or when it is in the pole of the ecliptic (when it is a circle). As aberration depends upon the ratio between the velocity of light and the velocity of the Earth, the determination of this ‘constant of aberration’ provides a method of calculating an approximate value for one of these velocities if the other is known.

The cog-wheel and rice plant stand for industry and agriculture. The stars represent the 14 states. Blue symbolizes peace. Red denotes courage. Effective date: 4 January 1974. >>