6 days ago · On the basis of appearance, nebulae can be divided into two broad classes: dark nebulae and bright nebulae. Dark nebulae appear as irregularly shaped black patches in the …

On the basis of appearance, nebulae can be divided into two broad classes: dark nebulae and bright nebulae. Dark nebulae block the light of the stars that lie beyond them and appear as …

Mar 9, 2025 · Planetary nebula, any of a class of bright nebulae that are expanding shells of luminous gas expelled by dying stars. They have a relatively round compact appearance …

6 days ago · Most are clusters of stars, 35 are galaxies, and 11 are nebulae. Even today many of these objects are commonly referred to by their Messier catalog number; M20, for instance, is …

Nebula - Gas, Dust, Radiation: Many characteristics of nebulae are determined by the physical state of their constituent hydrogen, by far the most abundant element.

A nebula is a cloud of gas and dust in space. Nebulas appear in many shapes and colors. Sometimes a nebula blocks out the light of stars beyond it. When this happens, the nebula …

Feb 14, 2025 · solar nebula, gaseous cloud from which, in the so-called nebular hypothesis of the origin of the solar system, the Sun and planets formed by condensation. Swedish philosopher …

reflection nebula, interstellar cloud that would normally be a dark nebula (or molecular cloud) but whose dust reflects the light from a nearby bright star that is not hot enough to ionize the …

5 days ago · What are the types of galaxies? Galaxy classification is based on the scheme proposed by the American astronomer Edwin Hubble . Hubble’s scheme is based on the …

Mar 25, 2025 · Galaxy - Novae, Andromeda, Nebula: An unfortunate misidentification hampered the early recognition of the northern sky’s brightest nearby galaxy, the Andromeda Nebula, …