solar parallax

from the GNU version of the Collaborative International Dictionary of English.

• The parallax of the sun, that is, the angle subtended at the sun by the semidiameter of the earth. It is 8.”80, and is the fundamental datum.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the angle subtended by the mean equatorial radius of the Earth at a distance of one astronomical unit