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 sky and blot out the light of the stars that lie beyond them.

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 irregularly shaped black patches in the sky.

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 rather than the chaotic patchy shapes of other nebulae—hence their name, which was given because of their resemblance to planetary

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 the great Trifid Nebula, in the constellation Sagittarius. The work of the Herschels

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 may look like a dark cloud. Other times a nebula glows a bright color, such as blue or red.

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 Emanuel Swedenborg in 1734 proposed that the planets formed out of a nebular crust that had surrounded the Sun and then broken apart.

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 cloud’s hydrogen.

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 optical appearance of galaxy images and divided into three general classes: ellipticals, spirals, …

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, also known as M31. In 1885 a bright star, previously invisible, appeared near the centre of M31, becoming almost bright enough to be seen without a telescope.