The 3 types of galaxies are:
Galaxies are just large accumulation of stars, planets, and other solar remnants. Astronomers estimate as many as 100 billion galaxies in the expanding universe. We observe galaxies using the Kepler and Hubble Telescopes. Galaxies are flat because things that rotate flatten out on the rotational access. Let’s see some examples of Edwin Hubble’s galaxy classification scheme. 1. Spiral Galaxy ClassificationTwo examples of the spiral galaxies are:
MILKY WAY: The entire Milky Way galaxy rotates in a clockwise direction. Its disk contains dust, stars, and gas rotating from a center point. The Milky Way is a flattened disk with spiral arms. The sun that provides heat to our planet belongs to one of the arms in the barred spiral galaxy. According to the Hubble Galaxy classification scheme, the Milky Way is an SBc barred spiral galaxy. Astronomers believe that it’s partway between SBb and SBc. ANDROMEDA GALAXY: Our nearest neighbor is the Andromeda Galaxy which is a spiral galaxy as well. It’s classified as a SA(s)b galaxy classification. 2. Elliptical galaxy classificationElliptical galaxies are circular in shape and elongated on a particular axis. The degree of ellipticity varies from E0 (circular) to E7 (elongated). Elliptical galaxies have a smooth gradient for brightness. Brightness progressively dimmers away from the center of the galaxy. This bulge of light at the center is a key difference between elliptical galaxies and other types of galaxies. 3. Irregular and lenticular galaxiesIrregular galaxies lack any form of symmetrical structure. They are unlike spiral galaxies because they don’t have distinct rotating arms. They are also unlike elliptical galaxies because they don’t have a definite center bulge. Irregular galaxies commonly have clouds of dust and cannot be characterized in the Hubble Galaxy Classification system. Similarly, lenticular galaxies are more of a transitional type of galaxy. They have lost most of their interstellar matter and are not forming stars of their own. What Are the 3 Types of Galaxies?In the vast expanse of space, there are hundreds of different galaxies. While many struggle to understand their magnitude and beauty, others are able to see them as they are- a beautiful display of life. If you find beauty in the universe, there are courses to learn more about its vastness. Here are some online course options to get started today.
We are always open to comments and questions. Please send us anything you have in the comment form below.
A galaxy is a large group of stars, gas, and dust bound together by gravity. Our solar system resides in the Milky Way galaxy, a spiral galaxy that is part of a group of galaxies called the Local Group.
There are billions of galaxies in the Universe, but only three outside our Milky Way Galaxy can be seen without a telescope - the Large and Small Magellanic Clouds and the Andromeda galaxy. The Large and Small Magellanic Clouds are about 160,000 light years away and are satellites of the Milky Way. They can be seen from the southern hemisphere. The Andromeda Galaxy is a larger galaxy that is about 2.5 million light years away and can be seen from the northern hemisphere with good eyesight and a very dark sky. The other galaxies are even further away from us and can only be seen through telescopes.
The smallest galaxies may contain only a few hundred thousand stars and be several thousand light years across, while the largest galaxies have trillions of stars and may be hundreds of thousands of light years across. Galaxies can be found by themselves, in small groups and in large clusters. It is very rare to find stars in the space in between galaxies. Galaxies sometimes collide with each other, with interesting results. These collisions can trigger bursts of star-formation in addition to changing the shapes of the galaxies that collide. However, when galaxy collisions occur, individual stars do not collide, due to the vast distances between them.
Interacting galaxies imaged by the Hubble Space Telescope. (Credit: NGC 4676: NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M.Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA; Antennae: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration UGC 8334: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)) Galaxy classificationGalaxies are classified by shape. There are three general types: elliptical, spiral, and irregular. Perhaps the most familiar kind of galaxy are spiral galaxies. They have a distinctive shape with spiral arms in a relatively flat disk and a central "bulge". The bulge has a large concentration of stars. The arms and bulge are surrounded by a faint halo of stars. The bulge and halo consist mainly of older stars, where spiral arms have more gas, dust and younger stars. Our Milky Way Galaxy is a spiral galaxy. Some spiral galaxies are what we call "barred spirals" because the central bulge looks elongated – like a bar. In barred spirals, the spiral arms of the galaxy appear to spring out of the ends of the bar.
Examples of spiral galaxies imaged by the Hubble Space Telescope. (Credit: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration) As their name suggests, elliptical galaxies are round or oval, with stars distributed fairly uniformly throughout. They have a bulge and halo, like spiral galaxies, but don't have the flat disk of stars. The stars in ellipticals tend to be older. Irregular galaxies have no identifiable shape or structure to them. They are often chaotic in appearance, without a bulge or any trace of spiral arms. The different shapes and orientation of galaxies are a result of their history, which may have included interactions with other galaxies.
Examples of an elliptical galaxy (NGC 1132) and an irregular galaxy (NGC 1472A). (Credit: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration) Updated: February 2016 Additional Links
Related TopicsFor Educators
|
Galaxies are classified and named according to their
zusammenhängende Posts
Urheberrechte © © 2024 frojeostern Inc.
