What are the types of galaxies Galaxies are certainly among the most popular telescope targets for amateur astronomers. They show an incredibly wide range of size, shape, and internal structure has undoubtedly lead to their fascination a mong both amateurs and professional astronomers alike. they are vast groups of stars, dust, and gas ranging from a few thousand to nearly a million light-years in diameter. Their respective masses show a similarly broad range from less than a million to well over trillion solar masses. This variety of shape and form is far greater than in any other class of deep sky objects. Elliptical Galaxies Elliptical galaxy is a galaxy that is elliptical in "observed shape". they are generally composed of only old stars, with little dense gas a vailable for additional star formation. Dynamical measurement s show that many are tri-axial, geometric figures with different radii along each axis, and thus their shapes reflect the distribution of stellar orbits rather than being produced by a net rotation. In the "Hubble Classification", ellipticals are described according to apparent shape, from E0 for circular images to E7 for the most flattenedellipticals.Elliptical galaxies span a vast
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as a "DENSITY WAVE" moving through the disk, or by differential rotation shearing star-forming regions into
locally tilted segments. Thus spirals range from grand design patterns, with between two and four arms traceable
through complete turns around the galaxy, to flocculent galaxies, in which only small,discontinuous pieces of the
spiral pattern exist. Most spiral galaxies have at least a weak bar, an elongation of the nuclear bulge, in the plane of
the disk. Spirals are classified into various subtypes in the "Hubble Classification". Most maintain active star
formation and have a significant reservoir of interstellar gas to fuel additional generations of stars.
Famous Examples:
Triangulum Galaxy (M33 or NGC 598) about 3 million light years away in the constellation Triangulum.
Andromeda Galaxy (M31 or NGC 224) about 2.5 million light-years away in the constellation Andromeda.
Sunflower Galaxy (M63 or NGC 5055) about 37 light years away in the constellation Canes Venatici.
Whirlpool Galaxy (M51a or NGC 5194) an interacting spiral galaxy located at a distance of approximately 23
million light years in the constellation Canes Venatici.
Pinwheel Galaxy (M101 or NGC 5457) a face-on spiral galaxy distanced 25 million light years away in the
constellation Ursa Major.
This image shows the evolution of spiral galaxies, from fully formed structures to disheveled
collections of stars just beginning to form. These galaxies were captured in the GreatObservatories Origins Deep Survey and are presented in the IMAX short film "Hubble: GalaxiesAcross Space and Time." It takes billions of years for the light of a distant galaxy to reach Earth.
Consequently, we see such galaxies as they were in the past, and can thus assemble a rough
pictorial history of galaxy evolution. Credit: NASA, ESA, F. Summers and Z. Levay (STScI).
Hubble Space Telescope and NASA's Spitzer Space Telescope joined forces to create this
striking composite image of one of the most popular sights in the universe. Messier 104 iscommonly known as the Sombrero galaxy.