Why galaxies are important

We see the galaxy nearly edge-on, so the dark dust in its pancake-like disk appears to bisect a large, white, rounded core of stars. Roughly 29 million light-years away, the Sombrero can be spotted with a modest telescope in the constellation Virgo. The stunningly beautiful galaxy cluster Abell contains an astounding assortment of several hundred galaxies tied together by the mutual pull of gravity. Located approximately 4 billion light-years away in the constellation Cetus, the Sea Monster, this immense cluster is a rich mix of a variety of galaxy shapes.

The large Whirlpool Galaxy left is known for its sharply defined spiral arms. Their prominence could be the result of the Whirlpool's gravitational tug-of-war with its smaller companion galaxy right. Even its globular clusters are oddballs: they are twice as large as typical stellar groupings seen in other galaxies.

NGC also has what is known as a "grand design" disk structure in its nucleus—a spiral within a spiral. Knezek WIYN. The galaxy, called NGC , sparkles with the light from millions of newly formed young stars. NGC is pumping out stars at a rate that is times faster than the rate observed in our Milky Way Galaxy. This frenzied pace has been almost continuous for the past million years. Three of the galaxies in this famous grouping, Stephan's Quintet, are distorted from their gravitational interactions with one another.

One member of the group, NGC upper right is actually seven times closer to Earth than the rest. Astronomers find that the supermassive black hole at the center of the most massive local galaxy M87 is not where it was expected.

Their research, conducted using the Hubble Space Telescope, concludes that the supermassive black hole in M87 is displaced from the galaxy center. Batcheldor and E. Biretta, W. Sparks, and F. Macchetto STScI. This image shows the interacting galaxy pair called Arp The disk of the larger galaxy is distorted into a rose-like shape by the gravitational pull of the smaller companion galaxy. A swath of blue, jewel-like points along the edge is the combined light from clusters of bright and hot young stars.

The two spiral galaxies started to interact a few hundred million years ago, making the Antennae galaxies one of the nearest and youngest examples of a pair of colliding galaxies. In order to understand the nature and history of the universe, scientists study how the matter is currently organized and how that organization has changed through out cosmic time.

In fact, scientists examine how matter is distributed and behaves at multiple size scales in our quest for this understanding. From peering into the way matter is constructed at the subatomic particle level to the immense structures of galaxies and dark matter that span the cosmos, each scale gives us important clues as to how the universe is built and evolves.

Telescopes like the Hubble have captured many beautiful images of majestic spiral galaxies, like this one, which is called NGC But galaxies have not always looked this way.

The grand spirals we are so familiar with indeed including our own were formed over the course of billions of years by several different processes, including the collisions of smaller galaxies. Giant elliptical galaxies are thought to also be formed by the process of similar-sized galaxies colliding [see videos linked at the bottom of the page], disrupting each other, and merging.

In fact, it is thought that nearly all massive galaxies have undergone at least one major merger since the Universe was 6 billion years old. When we look at very distant galaxies, we see a completely different picture. Many of these galaxies tend to be small and clumpy, often with a lot of star formation occurring in the massive knots. The question of how these clumpy galaxies evolve and develop structure over time is a big open question in astronomy, and JWST will help astronomers to learn more.

NGC is a glorious spiral galaxy around half the size of the Milky Way. Other unanswered questions about galaxies include the following. How did the first galaxies form? How did we end up with the large variety of galaxies we see today? We see not only organized and structured spiral galaxies in the modern universe, we also see those giant ellipticals we mentioned earlier, and galaxies in a wide variety of irregular shapes and sizes.

We now know that extremely large black holes live at the centers of most galaxies but what is the nature of the relationship between the black holes and the galaxy that hosts them? There is also more to understand about the mechanisms that cause star formation-- whether it happens internal to a galaxy or because of an interaction with another galaxy or merger. One thing we do know is that galaxies are still forming and assembling today.

There are many, many examples of galaxies colliding and merging to form new galaxies. And in our own local neighborhood of space, the Andromeda galaxy is headed toward the Milky Way for a likely future collision many billions of years from now! Fun fact: space is so big that when galaxies collide, the stars within them rarely do.

How are galaxies are formed? In the other, the generally-higher metallicity of large elliptical galaxies is likely to result in a disproportionately higher number of gaseous planets in large elliptical galaxies — meaning less rocky aka. As Whitmire said :. These galaxies went through an early phase in which there is so much radiation that it would just completely have nuked any habitable planets in the galaxy and subsequently the star formation rate, and thus any new planets, went to essentially zero.

There are no new stars forming and all the old stars have been irradiated and sterilized. This study is similar to research conducted in recent years that have reconsidered questions relating to planetary habitability. While this study casts doubt on giant elliptical galaxies being the best place to look for intelligent life, it means that SETI efforts are best directed at our own galaxy and those like it. Sure, there could be a lot more gas planets, but so many that less than one Earth in 10, escapes?

Principle of Mediocrity] are tricky to get to work right, and are nearly always trumped by any kind of data. So we need to get more data. But both Whitmire and Sandberg overlook the fact that the paper included gas giant densities since they may host moons that could be habitable.