NASA; ESA; G. Illingworth, D. Magee, and P. Oesch, university of California, Santa Cruz; R. Bouwens, Leiden University; and the HUDF09 Team

For numerous thousands of years, humanity has peered up in ~ the night sky with one question optimal of mind: what rather is out there?

There"s the moon (8), of course, and also then the sun. And as our check out of the night sky has come into sharper focus, we"ve uncovered other objects, too, choose the seven other planets the orbit the sun and also their numerous moons. We spotted comets and asteroids, black holes and galaxies, packed complete of numerous stars. On especially dark nights, friend can also spot the edges of our very own Milky way galaxy.

So precisely how many galaxies are out there? present estimates imply there may be as countless as 2 trillion—that"s trillion with a T— galaxies in the observable universe.

Each galaxy has its very own unique set of features and also characteristics. End the food of countless years, they form gases, dust, stars, planets and also moons. In ~ the facility of most galaxies lies a supermassive black color hole, i m sorry tugs at surrounding stars.

Famed astronomer Edwin Hubble ended up being the an initial to devise a galactic category system for the celestial features in 1926. According to his (very simplified) classification, there are five main species of galaxies: spiral, barred spiral (the Milky way is a ban spiral), lenticular, elliptical, and irregular.

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Intergalactic Arithmetic


Only in recent years have actually we to be able to estimate and understand exactly how much rather there is in the universe. Scientists use telescopes favor the Earth-orbiting Hubble an are Telescope and Chandra X-ray Observatory and also the European southern Observatory"s Earth-based Very big Telescope to lug out galactic surveys and identify how numerous galaxies space in a patch of the skies the dimension of a pinhead organized at arm"s length.

Counting galaxies is kind of favor playing a cosmic video game of Where"s Waldo. Astronomers are tasked v counting every galaxy they can find within that tiny sliver of room and then extrapolate that out throughout the whole sky.

Carving a fraction out of the sky and also identifying every one of the galaxies in it throughout the large spectrum of wavelength is not an easy task. You have to fight through dust and other matter that may dampen a galaxy’s light. And also it take away a lengthy time because that Hubble and also other telescopes to take it these images and also stitch them together.

There are without doubt galaxies that us can’t even see. Due to the fact that our universe is expanding, some very distant and also old galaxies, which formed shortly after the big bang, room zooming far from us faster than the speed of light. It’s virtually impossible to spot them with current technology.

Hubble go Deep

We largely have actually the Hubble space Telescope to thank for illuminating our ar in the universe. When it isn"t chasing comets or counting planetary rings, Hubble regular snaps thorough pictures of small slices that the sky. Hubble exit the very first Deep field survey in 1995.

"We to be trying to find sort of one indiscriminate area the the sky where no observation had been make before," Robert Williams, the former director that the space Telescope scientific research Institute, called Vox in 2016. The photo revolutionized astronomy. Indigenous the glittering image, astronomers spotted around 1,500 glittering galaxies. Subsequent images revealed even more.

In 2012, Hubble’s excessive Deep ar image to be released. Over the food of ten years, the telescope had snapped pictures of a small patch of sky for a total of 50 days. That revealed a part of sky—about one thirty-two millionth the the sky, to be exact—scattered with twinkling galaxies of every shapes and also sizes. Making use of this brand-new image, astronomers approximated that there may be 100 to 200 exchange rate galaxies in the observable universe.

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But just four years later, a team of researchers from the college of Nottingham reanalyzed Hubble’s images and also assessed data from various other observatories, pulling our universe-wide galaxy counting up through a element of 10 to 2 trillion. The astronomers released their new numbers in the Astrophysical Journal.

“It boggles the mind that over 90 percent that the galaxies in the Universe have actually yet to be studied,” astrophysicist Christopher Conselice that the university of Nottingham in the UK said the Atlantic in ~ the time. “Who to know what amazing properties we will find when we discover these galaxies with future generations of telescopes?”

Next Generation Estimates

In a sense, we’re playing a game of cat and also mouse v the universe. We’re scrambling to build instruments powerful enough to catch sight the galaxies that are zipping far from us at break-neck speeds. The upcoming James Webb an are Telescope is slated to take Hubble’s reins as the preeminent galaxy spotting space telescope.

The infrared observatory is 100 times more powerful than Hubble and also will have the capacity to probe the cosmos in greater detail than ever before before, spotting distant galaxies too faint because that every ahead generation the telescopes to see. Astronomers hope to see galaxies that created just ~ the large Bang, approximately 13.5 billion year ago. It"ll provide us the closest look yet to the start of everything.

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Jennifer LemanJennifer Leman is a science journalist and news editor at popular Mechanics, whereby she writes and also edits stories about science and space.
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