Galaxies are huge collections of stars that occupy our universe. But how lots of galaxies are there? Counting them seems like an impossible job. Large numbers is one problem– once the count gets into the billions, it takes a while to do the addition. Another issue is the limitation of our instruments. To get the best view, a telescope needs to have a large aperture (the size of the main mirror or lens) and be located above the environment to avoid distortion from Earths air.Perhaps the most resonant example of this fact is the Hubble eXtreme Deep Field (XDF), an image made by combining 10 years of photographs from the Hubble Space Telescope. The telescope saw a small spot of sky in repeat sees for an overall of 50 days, according to NASA. The XDF area would be about the size of the head of a pin if you held your thumb at arms length to cover the moon. By collecting faint light over numerous hours of observation, the XDF revealed countless galaxies, both really far-off and close-by, making it the deepest picture of deep space ever taken at that time. If that single small spot contains thousands, think of how many more galaxies could be discovered in other spots.While price quotes amongst various experts differ, an acceptable range is in between 100 billion and 200 billion galaxies, said Mario Livio, an astrophysicist at the Space Telescope Science Institute in Baltimore, Maryland. The James Webb Space Telescope is expected to expose a lot more details about early galaxies in deep space, according to The Astrophysical Journal. Going deepThe Hubble Space Telescope has been use to study galaxies and their numbers. (Image credit: Getty Images) According to Livio, the Hubble Space Telescope has actually been effective for galaxy counting and estimation. The telescope, launched in 1990, at first had a distortion on its primary mirror that was remedied throughout a shuttle go to in 1993. Hubble likewise went through several upgrades and service sees until the last shuttle bus mission there in May 2009. In 1995, astronomers pointed the telescope at what seemed an empty area of Ursa Major, and collected 10 days worth of observations. The result was an estimated 3,000 faint galaxies in a single frame, going as dim as 30th magnitude, according to Weber State University. (For contrast, the North Star or Polaris is at about 2nd magnitude.) This image composite was called the Hubble Deep Field and was the farthest anybody had seen into the universe at the time. As the Hubble telescope got upgrades to its instruments, astronomers repeated the experiment two times. In 2003 and 2004, scientists produced the Hubble Ultra Deep Field, which in a million-second exposure revealed about 10,000 galaxies in a little spot in the constellation Fornax.In 2012, once again utilizing updated instruments, scientists used the telescope to look at a part of the Ultra Deep Field. Even in this narrower field of view, astronomers were able to identify about 5,500 galaxies. Scientist dubbed this the eXtreme Deep Field.All in all, Hubble exposes an estimated 100 billion galaxies in deep space or two, but this number is likely to increase to about 200 billion as telescope innovation in area improves, Livio informed Space.com.Counting starsThe Hubble Space Telescope captured this image of the stars in the NGC 5023 galaxy. (Image credit: ESA/NASA) Whatever instrument is utilized, the technique of estimating the number of galaxies is the same. You take the part of sky imaged by the telescope (in this case, Hubble). — utilizing the ratio of the sliver of sky to the whole universe– you can figure out the number of galaxies in the universe.” This is presuming that there is no large cosmic difference, that deep space is homogenous,” Livio stated. “We have excellent reasons to suspect that is the case. That is the cosmological principle.” The principle goes back to Albert Einsteins theory of general relativity. Einstein said that gravity is a distortion of area and time. With that understanding in hand, numerous scientists (including Einstein) attempted to understand how gravity impacted the whole universe.” The easiest presumption to make is that if you viewed the contents of the universe with sufficiently poor vision, it would appear roughly the same all over and in every instructions,” NASA specified. “That is, the matter in deep space is isotropic and homogeneous when averaged over really large scales. This is called the cosmological principle.” One example of the cosmological principle at work is the cosmic microwave background (CMB), radiation that is a remnant of the early stages of deep space after the Big Bang. Utilizing instruments such as NASAs Wilkinson Microwave Anisotropy Probe, astronomers have found the CMB is practically similar wherever one looks.Would the number of galaxies change?As deep space broadens, galaxies move far from Earth. (Image credit: MARK GARLICK/SCIENCE PHOTO LIBRARY via Getty Images) Measurements of deep spaces expansion– through seeing galaxies race away from us– reveal that it has to do with 13.82 billion years old. As the universe ages and bigger, nevertheless, galaxies will decline further and further from Earth. This will make them harder to see in telescopes.The universe is broadening much faster than the speed of light (which does not breach Einsteins speed limit because the growth is of the universe itself, rather than of objects taking a trip through the universe). The universe is accelerating in its expansion.This is where the concept of the “observable universe”– the universe that we can see– comes into play. In 1 trillion to 2 trillion years, Livio stated, this means that there will be galaxies that are beyond what we can see from Earth.” We can just see light from galaxies whose light had adequate time to reach us,” Livio said. “It does not mean that thats all there is in the universe. The meaning of the observable universe.” Galaxies also change in time. The Milky Way is on a clash with the neighboring Andromeda Galaxy, and both will merge in about 4 billion years. In the future, other galaxies in our Local Group– the galaxies closest to us– will eventually combine. Citizens of that future galaxy would have a much darker universe to observe, Livio said.” Civilizations began then, they would have no proof that there was a universe with 100 billion galaxies,” he stated. “They would not see the growth. They would probably not be able to tell there was a Big Bang.” What about other universes?Scientists hypothesize that our universe is not the only one. (Image credit: Getty Images) As the early universe inflated, there are some theories that say that various “pockets” broke away and formed various universes. These various locations might be broadening at various rates, consist of other kinds of matter, and have various physical laws than our own universe.Livio explained there might be galaxies in these other universes– if they exist– but we have no way today of knowing for sure. So the number of galaxies might even be higher than 200 billion, when considering other universes.In our own universes, Livio said, astronomers will be better able to fine-tune the number with the launch of the James Webb Space Telescope (for which his institute will manage the objective operations and science). Hubble has the ability to peer back at galaxies that formed about 450 million years after the Big Bang. Utilizing the James Webb telescope, astronomers expect they can look as far back as 200 million years after the Big Bang.” The numbers are not going to change much,” Livio added, mentioning the very first galaxies probably formed not too long before that. “So a number like 200 billion [galaxies] is most likely it for our observable universe.” Webbs contributionsWhile it is fascinating to count the variety of galaxies in our universe, astronomers are more thinking about how galaxies reveal how the universe was formed. According to NASA, galaxies are a representation of how matter in the universe was organized– a minimum of, on the large scale. (Scientists are also interested in particle types and quantum mechanics, on the small side of the spectrum.) Because Webb can look back to the early days of deep space, its information will help scientists better comprehend the structures of the galaxies around us today.The James Webb Space Telescope was released on 25 December 2021. (Image credit: Getty Images)” By studying a few of the earliest galaxies and comparing them to todays galaxies, we may have the ability to comprehend their growth and evolution. Webb will likewise allow researchers to collect data on the types of stars that existed in these really early galaxies,” NASA stated of Webbs objective. ” Follow-up observations using spectroscopy of hundreds or thousands of galaxies will help researchers understand how elements much heavier than hydrogen were formed and developed as galaxy formation continued through the ages. These research studies will likewise reveal information about combining galaxies and shed light on the process of galaxy development itself.” According to NASA, here are a few of the essential concerns Webb will answer about galaxies: How are galaxies formed?What provides their shapes?How are the chemical components dispersed through the galaxies?How do the central great voids in galaxies influence their host galaxies?What occurs when small and big galaxies clash or join together?Scientists are likewise thinking about the function that dark matter plays in the assembly of galaxies. While a few of the universe shows up in kinds such as stars or galaxies, dark matter is what makes up most of the universe– about 80 percent of it. While dark matter is invisible in wavelengths of light or through emissions of energy, studies of galaxies dating back to the 1950s showed there was far more mass present in them than what showed up with the naked eye.” Computer designs that researchers have actually made to comprehend galaxy formation suggest that galaxies are created when dark matter merges and clumps together,” NASA said. ” It [dark matter] can be considered the scaffolding of deep space. The noticeable matter we see collects inside this scaffolding in the form of galaxies and stars. The method dark matter clumps together is that little things form first, and are drawn together to form bigger ones.” Webbs effective mirrors will allow researchers to take a look at galaxy development– consisting of the role of dark matter– up close. While this examination does not directly respond to the number of galaxies there remain in the universe, it does assist scientists much better comprehend the processes behind the galaxies we see, which in turn better notifies models about stellar populations.Additional resourcesYou can see thousands of galaxies, taken in one photograph, in this image taken by NASAs Hubble Space Telescope. To learn more about the different types of galaxies, head to NASAs Hubblesite.Bibliography” Oases in the dark: galaxies as probes of the Cosmos”. Astrophysics and Astronomy Commons (2007 ). http://sciencejedi.com/professional/talks/ynp_galaxies.pdf” Galaxy number counts– V. Ultradeep counts: the Herschel and Hubble Deep Fields”. Monthly Notices of the Royal Astronomical Society, Volume 323, Issue 4 (2001 ). https://academic.oup.com/mnras/article/323/4/795/1102609?login=true” Finding High-redshift Galaxies with JWST”. The Astrophysical Journal (2021 ). https://iopscience.iop.org/article/10.3847/1538-4357/ac2a2f/meta
Researchers dubbed this the eXtreme Deep Field.All in all, Hubble reveals an estimated 100 billion galaxies in the universe or so, however this number is most likely to increase to about 200 billion as telescope innovation in area enhances, Livio informed Space.com.Counting starsThe Hubble Space Telescope captured this image of the stars in the NGC 5023 galaxy. Later on, other galaxies in our Local Group– the galaxies closest to us– will eventually integrate.” Follow-up observations using spectroscopy of hundreds or thousands of galaxies will assist scientists understand how aspects heavier than hydrogen were formed and constructed up as galaxy development continued through the ages.” According to NASA, here are some of the key concerns Webb will answer about galaxies: How are galaxies formed?What offers them their shapes?How are the chemical aspects dispersed through the galaxies?How do the central black holes in galaxies affect their host galaxies?What occurs when little and large galaxies clash or join together?Scientists are also interested in the function that dark matter plays in the assembly of galaxies. While this investigation doesnt straight respond to how numerous galaxies there are in the universe, it does assist researchers much better understand the procedures behind the galaxies we see, which in turn better notifies designs about galactic populations.Additional resourcesYou can see thousands of galaxies, taken in one picture, in this image taken by NASAs Hubble Space Telescope.
