Ordinarily, we allude telescopes at part object we desire to check out in better detail. In the 1990s astronomers walk the opposite. Castle pointed the most powerful telescope in history, the Hubble room Telescope, in ~ a dark patch of sky devoid of recognized stars, gas, or galaxies. But in the sliver of nothingness, Hubble revealed a breathtaking sight: The void to be brimming v galaxies.

You are watching: How many galaxies are out there

Astronomers have actually long wonder how plenty of galaxies there room in the universe, yet until Hubble, the galaxies we can observe were far outnumbered by fainter galaxies concealed by distance and also time. The Hubble Deep Field collection (scientists make two much more such observations) available a type of core sample of the cosmos going earlier nearly to the huge Bang. This enabled astronomers to lastly estimate the galactic population to it is in at least roughly 200 billion.

Why “at least”? since even Hubble has actually its limits.

The more out (and earlier in time) you go, galaxies gain harder come see. One reason of this is the pure street the light must travel. A 2nd reason is due to the development of the universe. The wavelength that the irradiate of really distant objects is stretched (redshifted), so these objects have the right to no longer be watched in the primarily ultraviolet and also visible parts of the spectrum Hubble was designed come detect. Finally, theory says early galaxies to be smaller and fainter to start with and only later combined to kind the colossal frameworks we view today. Researchers are confident this galaxies exist. We just don’t recognize how many there are.

In 2016, a study released in The Astrophysical Journal through a team led by the college of Nottingham’s Christopher Conselice used a mathematical version of the early on universe to calculation how numerous of those as-yet-unseen galaxies room lurking just past Hubble’s sight. Included to present Hubble observations, your results said such galaxies make up 90 percent the the total, bring about a new estimate—that there might be up to 2 trillion galaxies in the universe.

Such estimates, however, space a relocating target. As an ext observations role in, researchers can gain a far better handle on the variables at play and increase the accuracy of their estimates.

Which brings us to the most recent addition to the story.

After buzzing by Pluto and also the bizarre Kuiper Belt object, Arrokoth, NASA’s brand-new Horizons spacecraft is at the sheet of the solar device cruising toward interstellar space—and recently, it traction a Hubble. In a research presented this week in ~ the American Astronomical society and soon to be released in The Astrophysical Journal, a team led by astronomers Marc Postman and Tod Lauer explained what they discovered after maintain the brand-new Horizons telescope on seven slivers that empty space to shot and measure up the level the ambient irradiate in the universe.

Their findings, castle say, enabled them to create an upper limit top top the number of galaxies in existence and indicate space may it is in a little less crowded than previously thought. According to your data, the total number of galaxies is much more likely in the thousands of billions, no trillions. “We simply don’t check out the irradiate from two trillion galaxies,” mail carrier said in a relax published previously in the week.

How walk they arrive at their conclusion?

The search for Perfect Darkness

There is one an ext constraint top top Hubble’s observations. Not just can’t it directly resolve early galaxies, the can’t also detect your light due to the diffuse light of “zodiacal light.” led to by a aur of dust scattering irradiate within the solar system, zodiacal irradiate is extremely faint, but just like light pollution on Earth, it can obscure also fainter objects in the early on universe.

The new Horizons spacecraft has now escaped the domain that zodiacal light and is gazing in ~ the darkest sky yet imaged. This provides the opportunity to measure the background irradiate from beyond our galaxy and compare it to known and also expected sources.

Postman said The new York Times the going an stimulate of magnitude more wouldn’t have available a darker view.

“When you have actually a telescope on brand-new Horizons method out in ~ the leaf of the solar system, you have the right to ask, how dark does an are get anyway,” Lauer wrote. “Use her camera simply to measure the glow native the sky.”

Still, the measure up was not straightforward. In an article, astrophysicist and also writer Ethan Siegel, that was not component of the study, defines how the team conscientious identified, modeled, and also removed contribute from “camera noise, scattered sunlight, excess off-axis starlight, crystals native the spacecraft’s thrust, and also other critical effects.” They also removed any type of images also close to the Milky Way. After all this, they to be left through the faint glow of the universe, and also that’s the amazing bit.

The 2016 examine predicted the a universe with two trillion galaxies would certainly produce around ten times an ext light than the galaxies we’ve so much observed indicate. However the new Horizons team only found around twice as much light. This led lock to your conclusion over there are most likely fewer total galaxies lurking the end there than formerly thought—a number closer come the original Hubble estimate.

“Take every the galaxies Hubble deserve to see, twin that number, and that’s what we see—but naught more,” said Lauer.

Star Gazing: The following Generation

These monitorings from new Horizons aren’t the finish of the story. Our capacity to watch the earliest world should gain a foot up this year when (fingers crossed) Hubble’s successor, the James Webb space Telescope will launch and begin operations.

See more: 10 Minute Recipe How Long Do You Boil A Hot Dog S: Learn In 5 Easy Steps

The JWST is collection to watch in much longer wavelengths than Hubble and also is lot bigger. These characteristics should allow it come see also further back and photo those smaller, fainter first galaxies. Favor the Hubble Deep Field, if all is in working order, including those galaxies to the census should give us an even clearer picture of the whole.

Whatever number scientists finally land on, it’s unlikely to it is in anything yet mind-bogglingly huge. Even a few hundred billion galaxies method there’s one entire galaxy out there because that every star in the Milky Way. Such study will undoubtedly cast even much more light on cosmological questions around how the cosmos formed. Yet it will additionally beg the question: amid the vast sea that galaxies, stars, and also planets, room we really the only types to ever before look out and also wonder if we’re alone?