Because of the obscuration of dust in the Galaxy, only about 1,800 planetary nebulae have been cataloged.
The fading was due, at least in part, to obscuration by dust emitted in the earlier eruption.
However, much of this seeming chaos is spurious, caused by obscuration of dust in dark foreground neutral material rather than by the actual distribution of ionized material.
The Galaxy contains more than 150 globular clusters (the exact number is uncertain because of obscuration by dust in the Milky Way band, which probably prevents some globular clusters from being seen).
The Milky Way Galaxy contains more than 150 globular clusters (the exact number is uncertain because of obscuration by dust in the Milky Way band, which probably prevents some globular clusters from being seen).
In 1926 he showed that, apart from a "zone of avoidance" (region characterized by an apparent absence of galaxies near the plane of the Milky Way caused by the obscuration of interstellar dust), the distribution of galaxies in space is close to uniform when averaged over sufficiently large scales, with no observable boundary or edge.
One by one, participants wrote off possible confounding factors--such as obscuration by cosmic dust or errors estimating a star's distance--that could spoil this scenario.
The faint galaxy, which lies in the direction of the constellation Sagittarius, had remained undetected because of obscuration caused by stars and dust lying in the disk of the Milky Way.
A small amount of flux will be emitted and penetrate the dust clump at a glancing angle, leading to obscuration and dichroic polarisation from only a portion of the dust clump (see Fig. 5).
Types included in surface weather observations include precipitation, obscurations, other weather phenomena such as, well-developed dust/sand whirls, squalls, tornadic activity, sandstorms, volcanic ash, and dust storms.
