It’s difficult to know for sure, however Hubble revealed the there are at the very least 100 exchange rate galaxies in the universe. However, this may be a conservative estimate — other estimates put the total variety of galaxies at 2 trillion.

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These room all galaxies, so here goes: one, two, three…Image credits: Hubble.

What is a galaxy

Before us start looking for galaxies and also counting them, we need to know simply what a galaxy is.

Essentially, a galaxy is a huge collection the gas, dust, andbillionsof starsall tied with each other by gravity. Although the distances between stars within the very same galaxy have the right to be huge, it’s vital that they’re all connected into a solitary cluster by heaviness — that’s what provides it a galaxy. Many galaxies have a supermassive black hole at your center, which helps keep it every together. As the surname implies, supermassive black color holes space immensely enormous black holes — they have actually a massive on the bespeak of millions or even billions that solar masses.

There space three varieties of galaxies: elliptical, spiral, and irregular. The surname pretty much explains the in its entirety shape of the galaxy: elliptical galaxies look like an “egg” of light (an ellipse), spiral galaxies extend arms around the central bulge, and also irregular galaxies space pretty much every little thing that’s no spiral or elliptical. The Milky Way, our own galaxy, is a spiral galaxy. It seems strange that facility and varied systems such together galaxies take on such few shapes. Researchers space still not precisely sure why this happens, however these common shapes are likely the product that rotation speed, time and also gravity.

The Pinwheel Galaxy, NGC 5457. A standard spiral galaxy. Picture credits: Hubble.

Galaxies can additionally vary considerably in size, which way that some are an ext easily visible than others. Dwarf galaxies have between 100 million and several exchange rate stars (a very small number contrasted to the Milky Way’s 200-400 exchange rate stars), measuring “only” 300 light-years. Meanwhile, “IC 1101” is the single largest galaxy the has ever been uncovered in the observable universe,spanning a whopping210,000 light-years across.

Looking because that galaxies

So exactly how does one look for galaxies? We deserve to all view (on clean nights) the bright, milk-ish band the lends our galaxy the name. An ext than 2,000 years ago, theGreek philosopher Democritus (450–370 BCE) proposed that the band might consist of remote stars, a how amazing insightful idea. That course, there are numerous things that Democritus couldn’t have known, and it wasn’t until1610 when the Italian astronomer Galileo Galilei supplied a telescope to examine the Milky means and discovered that it is composed of a huge variety of faint and very distant stars.

Fast forwarding to modern-day times, telescopes have obviously gained a lot better. But one that the biggest difficulties for every telescopes is the atmosphere, which includes a the majority of light pollution and distortion of electromagnetic radiation. Thankfully, astronomers have by-passed that problem by building an are telescopes — yes, we have telescopes in outer space. The most renowned one, although not the first, is the Hubble telescope. Hubble is avital study tool i beg your pardon has listed an invaluable trove the data. Amongst others, the landmark Hubble Deep Field, bring away in the mid-1990s, gave the an initial real understanding into the universe’s galaxy population.

The Antennae Galaxies, featured here, will eventually merge. Picture credits: Hubble.

But even with Hubble, count galaxies is extremely daunting for the an easy fact the the universe is, well, very big. Feather in all directions and also counting all the galaxies is nigh impossible, so instead, astronomers just emphasis on a ar of the night sky, count the galaxies there, and extrapolate based on that value. That course, this can lead to part inaccuracies, yet given the sheer dimension of the universe and also the variety of galaxies, the inaccuracies room unlikely to be significant.

How plenty of galaxies space there

So, back to the question: how plenty of galaxies are there? The very first measurements native the 1990s uncovered that there space 200 billion galaxies in the universe. However, that number is unlikely to be reliable.Subsequent sensitive observations discovered that plenty of faint galaxies were no observed the very first time. The most recent, and likely the most accurate, survey found that the real number of galaxies is ten time larger: so, in total, there space 2 trillion galaxies in the universe, or 2,000 billion, if girlfriend prefer.

In late 2016,Christopher Conselice, Professor the Astrophysics at the university of Nottingham, along with several colleagues, brought out a sort of historical cosmology: they calculatedthe density of galaxies and the volume of one small an ar of space after another. This painstaking research was the culmination the 15 year of research, and also it permitted the team to create how numerous galaxies we have missed. The team uncovered that, initially, astronomers missed a lot of galaxies because they were faint and really far away.

“We are lacking the vast majority of galaxies since they are very faint and also far away. The number of galaxies in the universe is a an essential question in astronomy, and also it boggles the mind the over 90% of the galaxies in the cosmos have actually yet to be studied. Who knows what interesting properties we will find when we research these galaxies v the next generation that telescopes?”

Each light speck is a galaxy, some of which space as old as 13.2 exchange rate years. The cosmos is approximated to save on computer anywhere in between 200 billion and 2 trillion galaxies. Picture credits: Hubble.

Since numerous of the really distant galaxies are also faint, it appears that the total number of galaxies is right now decreasing over time. However, the more important takeaway lesson right here is that we’re still only seeing a very small portion of the universe. Who knows what we can be lacking out on. The study also says the the real variety of galaxies might be even higher — approximately 10 sunshine galaxies.

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“It boggles the mind the over 90% the the galaxies in the universe have yet to it is in studied,” comment Conselice. “Who to know what exciting properties us will uncover when we observe these galaxies with the following generation that telescopes?” he claimed in a statement.

Bonus: How numerous planets space there in the Universe?

If you’re still trying to wrap your mind about the variety of galaxies, here’s one more one. Estimating how plenty of planets there room in the world is much an ext a ballpark figure, and also relies much an ext on remove than straight observation. However for the fun of it, let’s perform some straightforward math. Let’s say there are 2 sunshine galaxies the end there. The Milky means is a fairly average galaxy, and it has actually over 200 billion planets. If us extrapolate based on that, we end up with 400 billion trillion planets in the universe. That’s 400,000,000,000,000,000,000,000 planets.

Again, this is absolutely an approximation and not scientifically accurate, yet it’s other to think about when friend feel favor you’re pretty important.

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Mihai Andrei

Andrei"s background is in geophysics, and also he"s been fascinated by that ever due to the fact that he was a child. Feeling that over there is a gap in between scientists and the general audience, he started ZME science -- and also the results are what you see today.