Many galaxies are there

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JPost NY Conference. Diplomatic Conference. IvritTalk- Free trial lesson. The Jerusalem Report. Elliptical galaxies may also be small, in which case they are called dwarf elliptical galaxies. Elliptical galaxies contain many older stars, but little dust and other interstellar matter. Their stars orbit the galactic center, like those in the disks of spiral galaxies, but they do so in more random directions.

Few new stars are known to form in elliptical galaxies. They are common in galaxy clusters. Lenticular galaxies , such as the iconic Sombrero Galaxy , sit between elliptical and spiral galaxies. Like elliptical galaxies, they have little dust and interstellar matter, and they seem to form more often in densely populated regions of space.

Galaxies that are not spiral, lenticular, or elliptical are called irregular galaxies. Irregular galaxies—such as the Large and Small Magellanic Clouds that flank our Milky Way—appear misshapen and lack a distinct form, often because they are within the gravitational influence of other galaxies close by.

They are full of gas and dust, which makes them great nurseries for forming new stars. Some galaxies occur alone or in pairs, but they are more often parts of larger associations known as groups, clusters, and superclusters. Our Milky Way, for instance, is in the Local Group , a galaxy group about 10 million light-years across that also includes the Andromeda galaxy and its satellites.

The Local Group and its neighbor galaxy cluster, the Virgo Cluster , both lie within the larger Virgo Supercluster , a concentration of galaxies that stretches about million light-years across. The Virgo Supercluster, in turn, is a limb of Laniakea, an even bigger supercluster of , galaxies that astronomers defined in Galaxies in clusters often interact and even merge together in a dynamic cosmic dance of interacting gravity.

When two galaxies collide and intermingle, gases can flow towards the galactic center, which can trigger phenomena like rapid star formation. Our own Milky Way will merge with the Andromeda galaxy in about 4. Because elliptical galaxies contain older stars and less gas than spiral galaxies, it seems that the galaxy types represent part of a natural evolution: As spiral galaxies age, interact, and merge, they lose their familiar shapes and become elliptical galaxies.

But astronomers are still working out the specifics, such as why elliptical galaxies follow certain patterns in brightness, size, and chemical composition.

The Milky Way, our own galaxy, is a spiral galaxy. It seems strange that complex and diverse systems such as galaxies take on such few shapes. Researchers are still not exactly sure why this happens, but these common shapes are likely the product of rotation speed, time and gravity.

Galaxies can also vary greatly in size, which means that some are more easily visible than others. Join the ZME newsletter for amazing science news, features, and exclusive scoops.

More than 40, subscribers can't be wrong. So how does one look for galaxies? We can all see on clear nights the bright, milk-ish band that lends our galaxy its name. More than 2, years ago, the Greek philosopher Democritus — BCE proposed that the band might consist of distant stars, a surprisingly insightful idea. Fast forwarding to modern times, telescopes have obviously gotten a lot better. But one of the biggest problems for all telescopes is the atmosphere, which contains a lot of light pollution and distortion of electromagnetic radiation.

Thankfully, astronomers have by-passed that problem by building space telescopes — yes, we have telescopes in outer space. On especially dark nights, you can even spot the edges of our own Milky Way galaxy. So exactly how many galaxies are out there? Current estimates suggest there may be as many as 2 trillion— that's trillion with a T — galaxies in the observable universe.

Each galaxy has its own unique set of features and characteristics. Over the course of millions of years, they form gases, dust, stars, planets and moons. At the center of most galaxies lies a supermassive black hole, which tugs at nearby stars.

Famed astronomer Edwin Hubble became the first to devise a galactic classification system for the celestial features in According to his very simplified classification, there are five main types of galaxies: spiral, barred spiral the Milky Way is a barred spiral , lenticular, elliptical, and irregular.

Only in recent years have we been able to estimate and understand how much else there is in the universe. Scientists use telescopes like the Earth-orbiting Hubble Space Telescope and Chandra X-ray Observatory and the European Southern Observatory's Earth-based Very Large Telescope to carry out galactic surveys and identify how many galaxies are in a patch of the sky the size of a pinhead held at arm's length.

Counting galaxies is kind of like playing a cosmic game of Where's Waldo. Astronomers are tasked with counting every galaxy they can find within that tiny sliver of space and then extrapolate it out across the entire sky.