Some articles on point symmetry, point, symmetry:
... It is the first bipolar PPN known to have point reflection symmetry (all others being axially symmetric) ... Point symmetry is a fairly common trait of planetary nebulae as found in NGC 2022, NGC 2371-2, NGC 6309, Cat's Eye Nebula, NGC 6563, Dumbbell Nebula, Saturn Nebula, A24, and Hb5 ... Morris Reipurth 1990 postulate that point symmetry is either due to the bipolar outflow being directed by a precessing disc or a precessing common envelope binary ...
Famous quotes containing the words symmetry and/or point:
“What makes a regiment of soldiers a more noble object of view than the same mass of mob? Their arms, their dresses, their banners, and the art and artificial symmetry of their position and movements.”
—George Gordon Noel Byron (17881824)
“All our Concord waters have two colors at least; one when viewed at a distance, and another, more proper, close at hand.... Walden is blue at one time and green at another, even from the same point of view. Lying between the earth and the heavens, it partakes of the color of both.”
—Henry David Thoreau (18171862)