The method of combining the signals received by several smaller telescopes distributed over a very large area or baseline to provide the high angular resolution of a much large telescope.
The point on the celestial sphere toward which the Sun is apparently moving relative to the local standard of rest. Its position, in the constellation Hercules, is approximately R.A. 18h, Dec. +30°, c
lose to the star Vega. The velocity of this motion is estimated to be about 19.4 km/sec (about 4 AU/year). As a result of this motion, stars seem to be converging toward a point in the opposite direction, the solar antapex.
The aphotic zone is the portion of a lake or ocean where there is little or no sunlight. It is formally defined as the depths beyond which less than 1% of sunlight penetrates. Consequently, biolumines
cence is essentially the only light found in this zone. Most food comes from dead organisms sinking to the bottom of the lake or ocean from other zones. The depth of the aphotic zone can be greatly affected by such things as turbidity and the season of the year. The aphotic zone underlies the photic zone, which is that portion of the ocean directly affected by sunlight.