<P> Stellar parallax is the apparent shift of position of any nearby star ( or other object ) against the background of distant objects . Created by the different orbital positions of Earth , the extremely small observed shift is largest at time intervals of about six months , when Earth arrives at exactly opposite sides of the Sun in its orbit , giving a baseline distance of about two astronomical units between observations . The parallax itself is considered to be half of this maximum , about equivalent to the observational shift that would occur due to the different positions of Earth and the Sun , a baseline of one astronomical unit ( AU ) . </P>
<P> Stellar parallax is the apparent shift of position of any nearby star ( or other object ) against the background of distant objects . Created by the different orbital positions of Earth , the extremely small observed shift is largest at time intervals of about six months , when Earth arrives at exactly opposite sides of the Sun in its orbit , giving a baseline distance of about two astronomical units between observations . The parallax itself is considered to be half of this maximum , about equivalent to the observational shift that would occur due to the different positions of Earth and the Sun , a baseline of one astronomical unit ( AU ) . </P>
measuring parallax from earth gives us a maximum baseline distance of approximately
measuring parallax from earth gives us a maximum baseline distance of approximately
two astronomical units
two astronomical units