Category Archives: Hubble Telescope

China will launch its Xuntian Telescope to unravel cosmic mysteries while challenging the technology of NASA Hubble Telescope. Heres how.

NASA Hubble Space Telescope is set to get a major rival and that too from China. Hubble Telescope has spent 32 years and discovered new galaxies, stars, planets, comets, asteroids and a lot more. And it's still counting! Now, China is preparing to explore the universe and unravel the cosmic mysteries as it is set to launch its flagship space telescope soon. It is named as the Chinese Space Station Telescope (CSST), or Xuntian which means 'survey to heavens. Authorities in Beijing claimed that it will compete with NASA's Hubble Telescope, Chinese news agency Xinhua reported. However, it should be known that NASA has already launched and placed in orbit a brand new one recently and it is called the James Webb Space Telescope. It is much better than the Hubble Telescope and can see much farther back in time and space than Hubble can.

About Chinas Xuntian Telescope

China's flagship telescope, set to launch at the end of 2023, is aimed at exploring new insights into faraway galaxies, mysterious dark matter and dark energy, as well as the universe's past and future evolution. The Chinese Survey Space Telescope (CSST), also known as the Chinese Space Station Telescope (CSST) as well as the Xuntian Space Telescope, is a space-based optical observatory that allows astronomers to conduct sky surveys and capture a general map or photos of the sky. The CSST is a bus-sized facility with a three-story building's length.

How will China's flagship telescope challenge the NASA Hubble Telescope? In an exclusive interview with Xinhua, Liu Jifeng, deputy director of the National Astronomical Observatories of China (NAOC), explained that while the telescope's aperture is two metres, it has a field of view 350 times greater than Hubble's. On the contrary, NASA Hubble Space Telescope includes a 2.4-meter (94-inch) primary mirror, a smaller secondary mirror, and multiple recording devices that can detect visible light, ultraviolet light, and infrared light.

The CSST has a three-mirror anastigmat design that allows it to achieve exceptional image quality over a wide field of view. It's also a Cook-type off-axis telescope with no obstructions that, when correctly sampled, may reach superior precision in photometry, location, and shape measurements.

Beijing's space agency, the China National Space Administration (CNSA), has planned to place the telescope in the same orbit as its space station, Tiangong, which will be operational by the end of 2023. The Xuntian telescope will likely be the largest space observatory monitoring the cosmos in near-ultraviolet and visible light.

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China to beat NASA Hubble Space Telescope with its Xuntian Telescope - HT Tech

A galaxy is a group of astronomical objects that are bound gravitationally.

Think of planets and their natural satellites, comets and asteroids, stars and stellar remnants (such as neutron stars or white dwarfs), the interstellar gasses between them, cosmic dust, and cosmic rays, dark matter, etc. All these items are held together by the force of gravity that keeps them attracted to each other to form a system. This system is called a galaxy.

The universe is full of galaxies. Scientists have estimated different numbers of galaxies thanks to data collected by telescopes and interplanetary space probes, such as NASAs Hubble Telescope and NASAs New Horizon spacecraft. In 2020, they calculated that there were about two trillion galaxies in the observable universe.

As you can imagine, not all of these galaxies have the same characteristics, and they definitely dont look the same. Astronomers have recognized several types of galaxies according to their visual appearance. This galaxy morphological classification system, known as the Hubble sequence, or Hubble Tuning Fork, was invented by American astronomer Edwin Hubble in 1926, and its a significant part of the study of galaxy evolution.

The scheme divides galaxies into categories based on their shape. It is roughlydivided into elliptical galaxies and spiral galaxies. Hubble gave the elliptical galaxies numbers from zero to seven, with E0 galaxies having an almost round shape and E7 very stretched out and elliptical.

The spiral galaxies were given letters from "a" to "c," with "Sa" galaxies appearing more tightly wound and "Sc" galaxies more loosely wound. The spiral galaxies were furthersub-divided into normal spirals and barred spirals (which have a B in their designation), with barred spirals containing a bar of stars running through the central bulge.

Lenticular galaxies, designated S0, represent a transition between ellipticals and spirals.

Hubble also found that some galaxies did not fit into this classification system - they had odd shapes, were very small or very large, etc. These are termed irregular galaxies.

The Hubble system was later extended byGrard de Vaucouleurs, whoargued that ringsandlensesare also important structural components of spiral galaxies. De Vaucouleurs' system keeps Hubble's basic division of galaxiesbut introduces a more elaborate classification system for spiral galaxies based on the presence and types of bars, rings, and spiral arms.

Elliptical galaxies are the most abundant. They have spherical or oval shapes. They are not very active as they dont have much gas and cosmic dust to form new stars. Consequently, elliptical galaxies are mostly made of old stars with low mass, and they are not as bright as other types of galaxies. They tend to contain less gas and dust than spiral galaxies, which means fewer stars are born, and existing stars tend to be older, giving off more red light. But they are kind of brighter at the center where star density is greater and where there is most likely a supermassive black hole. Presumably, this black hole supplies elliptical galaxies with the force of gravity necessary to keep the system together.

Elliptical galaxies account for around one-third of all known galaxies and between 10-27% of galaxies in the Virgo Supercluster, a mass concentration of galaxies that encompass the Virgo Cluster and the Local Group, two galaxy groups that contain the Milky Way galaxy (our "home" galaxy) and the Andromeda galaxy, one of our closest neighbors.

There are two subtypes of elliptical galaxies based on their sizes:

Spiral galaxies are thought to be the most recurrent in our universe. Around 60% of all galaxies are thought to be spiral galaxies.

As their name indicates, these galaxies are spiral-shaped. They consist of a flat, rotating disk of stars, cosmic dust, and interstellar gas, which spins around a central bulge made up of older, dimmer stars.The bulge is believed to contain a supermassive black hole.

The disk of stars orbiting the bulge separates into arms that circle the galaxy. These spiral arms contain a wealth of gas and dust and younger stars that shine brightly before their often rapid demise.

The bulge is surrounded by a galactic halo made of older, dimmer stars that are spread through several globular clusters (spherical groups of stars).

It is not fully understood what process creates and maintains the spiral arms.These galaxies rotate differentiallyeverything orbits at the same speed, so the time it takes to complete a full rotation increases with distance from the center. This differential rotation also causes any disturbance in the disk to wind up into a spiral form. If this were the only process involved in creating the spiral, we would likely see galaxies with a large number of tightly wrapped spiral arms.But most spiral galaxies have between two and four main arms.

Researchers believe the spiral form is also affected bydensity waves, which travel through the disk and cause stars and gas to "pile up" at the crest.

Our galaxy, the Milky Way, has four spiral arms two major arms called Scutum-Centaurus and Perseus and two minor arms named Norma and Sagittarius. It also has a number of branches made of fragments of the main arms. The Sun is located in one of these branches off the Sagittarius arm, called the Orion Spur.

Barred spiral galaxies are spiral galaxies in which the arms do not stretch all the way to the center but connect with the ends of a bar-shaped center made of bright, young stars. According to a 2008 study by NASA, bars form when stellar orbits in a spiral galaxy divert from their path after a process of destabilization that is usually linked to the galaxys age and evolution.

The affected stars in the spirals begin to describe a more elongated orbit that stretches out the center of the galaxy, so it ends up looking like an extended bar. This bar structure channels interstellar gas inflows towards the center of the spiral galaxy, which fuels star formation.

Approximately half of the known spiral galaxies have bars. In fact, the Milky Way is officially classified as a barred spiral galaxy.

Lenticular galaxies often share characteristics with both elliptical and spiral galaxies.

They are called lenticular because they are in the shape of a lens. They can be compared to spiral galaxies in that they have a galactic bulge and a flat disk surrounding them. However, they do not have spiral arms or clearly-defined spiral arms. Therefore, they don't appear spiral-shaped.

The formation of lenticular galaxies is not clearly understood.One theory is that lenticular galaxies used to be spiral galaxies that have grown old and consumed most of their gas and cosmic dust. In fact, lenticular galaxies do not produce an important number of new stars because they have run out of matter to do so. As a result, they are made of mostly old stars, like elliptical galaxies. Another prominent theory is that lenticular galaxies are formed when two spiral galaxies collide.

Irregular galaxies are called this because they do not have a distinct regular shape, and therefore, they donot neatly fit into any of the Hubble categories.

They lack spiral arms and a nuclear galactic bulge, and overall, they tend to look very chaotic. Some astronomers believe that irregular galaxies were originally elliptical or spiral galaxies that suffered from structural alterations due to mergers and/or interactions with other galaxies.

This is likely the case with the Magellanic Clouds, two irregular dwarf galaxies that orbit the Milky Way and were probably affected by its gravitational force, which distorted them into their current irregular shape.

Many irregular galaxies appear to be older than spirals but younger than ellipticals, leading someastronomers to hypothesize that irregular galaxies may be in an in-between stage.

Irregular galaxies can also be classified as Irregular I (Irr I), which feature some structure but not enough to be classified as another type of galaxy, and Irregular II (Irr II), which does not have any kind of recognizable structure at all. There are alsodIrr (dwarf irregular) galaxies.

Irregular galaxies are most frequently small, and they can contain lots of gas and cosmic dust, as well as both old and young stars.

Peculiar galaxies are those which do not fit in any other category of the Hubble classification scheme as they are unusual in shape, size, and/or composition.

They are believed to be formed by the collision of two or more galaxies, whose gravitational forces are constantly interacting with each other. This is why many peculiar galaxies can also be called interacting galaxies. This is also why they have extremely unusual shapes, an elevated rate of star formation, and more than one active central nucleus.

Perhaps some of the most famous peculiar galaxies are the Antennae Galaxies, which are interacting with each other in the constellation Corvus and are expected to fully collide (and become one) in about 400 million years.

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How many types of galaxies are there in the universe? - Interesting Engineering

Shepard Price,Digital reporter

March 28, 2022

The Hubble Telescope depicted in an artist's rendering with Earth in the background

NASA will make an announcement Wednesday regarding a new observation from the Hubble Telescope the agency says is "one for the record books."

The Hubble Telescope, launched almost 32 years ago, has worked for decades to "reshape our understanding of the universe," NASA wrote in a press statement. Hubble's work stretches from exploring exoplanets to galaxies to measuring the expansion of the universe, which has won the multi-observatory team a Nobel Prize.

NASA promises that the latest result "creates an exciting area of research for Hubble's future work with NASA's newly-launched James Webb Space Telescope," which launched on Dec. 25. The Webb telescope is scheduled to begin observation in June.

Hubble is expected to remain operational at least well into the 2020's, NASA has stated. Hubble used to be serviced every few years, but that ended in 2011 when the space shuttle program was retired. The last servicing mission to Hubble was in 2009.

Shepard Price has a Master's degree in Journalism from the University of Texas and lives in St. Louis. They have been in journalism for more than four years.

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NASA to make announcement Wednesday regarding Hubble Telescope - The Edwardsville Intelligencer

Hubbles most magnificent images With investigations into everything from black holes to exoplanets, the Hubble Telescope has changed not only the face of astronomy but also our very sense of being in the universe. On the 30th anniversary of its launch into low-earth orbit, this updated edition of Expanding Universe presents 30 brand new images, unveiling more hidden gems from the Hubbles archives.

Ultra-high resolution and taken with almost no background light, these pictures have answered some of the most compelling questions of time and space while also revealing new mysteries, like the strange dark energy that sees the universe expanding at an ever-accelerating rate.

The collection is accompanied by an essay from photography critic Owen Edwards and an interview with Zoltan Levay, who explains how the pictures are composed. Veteran Hubble astronauts Charles F. Bolden, Jr. and John Mace Grunsfeld also offer their insights on Hubbles legacy and future space exploration.

Charles F. Bolden, Jr., Major General, USMC (Ret.), is a former Administrator of NASA, where he oversaw the completion of the International Space Station. He spent 14 years as a member of NASAs Astronaut Corps, and commanded and piloted the Space Shuttle Discovery on STS-31, which launched the Hubble Space Telescope into orbit.

Owen Edwards has written about photography for more than 30 years for numerous publications including American Photographer, New York Times Magazine, and Smithsonian.

John Mace Grunsfeld, PhD, is an astrophysicist and a NASA astronaut. He has flown five times on the Space Shuttle, including three Hubble servicing missions. He has served as the Associate Administrator for the Science Mission Directorate, the NASA Chief Scientist, and as the Deputy Director of the Space Telescope Science Institute.

Zoltan Levay is a retired principle science visuals developer at the Space Telescope Science Institute, where he worked with astronomers and communicators worldwide to publicize science results from NASA's Hubble Space Telescope.

Hardcover with fold-outs, 11.4 x 11.4 in., 5.44 lb, 260 pages

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Expanding Universe. The Hubble Space Telescope - Taschen

The Hubble's Space Telescope captured a spectacular image of a Flame Nebula also known as NGC 2024. Located in the constellation Orion, NGC 2024 is a large star-forming region and is approximately 1,400 light-years away from Earth.

The Flame Nebula recently captured by the Hubble Space Telescope is particularly part of the Orion Molecular Cloud Complex, or popularly known as Orion Complex.

The Orion complex is one of the most active of those visible in the night sky located in the Milky Way.

As reported by NASA, the Flame Nebula captured is in the area where nebulae such as the Horsehead Nebula and the Orion Nebula are also located.

(Photo : NASA, ESA, and N. Da Rio (University of Virginia); Processing: Gladys Kober (NASA/Catholic University of America))NASAs Hubble Space Telescope captures another Flame Nebula.

This image captured by the Hubble Space Telescope focuses on the dark, dusty heart of the nebula, which contains a star cluster that is largely hidden from view by the surrounding dust.

The bright star Alnitak, the easternmost star in the Belt of Orion, is close by (but not visible in this image) and is the brightest star in the constellation. The hydrogen gas in the Flame Nebula is ionized as a result of the radiation from Alnitak.

In order for the gas to transition from a higher-energy state to a lower-energy state, it must first emit energy in the form of light. This causes the visible glow behind the swirling wisps of dust to appear.

Nebulas are large clouds of dust and gas that form in space. Several nebulae are formed by the explosion of a dying star, such as a supernova, which releases gas and dust into space. Other nebulae are regions where new stars are beginning to form, as opposed to the central nebula. Some nebulae are also referred to as "star nurseries" as a result of this phenomenon.

Nebulae are composed of dust and gasses, the majority of which are hydrogen and helium. Although the dust and gasses in a nebula are widely dispersed, gravity has the ability to gradually pull clumps of dust and gas together over time. Since these clumps grow in size, the gravitational pull of the clumps becomes stronger and stronger.

According to NASA's Space Place:"The clump of dust and gas gets so big that it collapses from its own gravity. The collapse causes the material at the center of the cloud to heat up-and this hot core is the beginning of a star."

Read Also: NASA's Space Launch System Rollout a Success! Next Stop: The Moon

NASA'sHubble Space Telescopehas taken numerous images of faraway nebulae. This extremely powerful microscope has been used by astronomers "to measure the mass of stars in the cluster as they search for brown dwarfs, a type of dim object that's too hot and massive to be classified as a planet but also too small and cool to shine like a star."

The Hubble Space Telescope is a large, space-based observatory named in honor of the trailblazing astronomer Edwin Hubble.

The Hubble Telescope has the scientific ability to have a crystal-clear view of the universe. It is located far above rain clouds, light pollution, and atmospheric distortions. Researchers have made use of the Hubble Space Telescope to observe some of the most distant stars and galaxies that have ever been observed, as well as the planets of our solar system.

When the Hubble Space Telescopewas launched into orbit around the Earth, it became the world's first astronomical observatory to be equipped with the capability of recording images in wavelengths of light ranging from ultraviolet to near-infrared.

Related Article: NASA Mars Rover Pictures: Perseverance Snaps Out-of-Place Photo of Drill Bit From 2021!

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#SpaceSnap: Hubble Space Telescope's Photo of the Heart of the Flame Nebula - iTech Post

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A piece of junk DNA could be the key to extinguishing fear-related memories for people struggling with post-traumatic stress disorder and phobia, according to a new study.

Researchers discovered the new gene while investigating how the genome responds to traumatic experiences.

Its like harnessing the power of the Hubble Telescope to peer into the unknown of the brain.

Until recently, scientists thought the majority of our genes were made up of junk DNA, which essentially didnt do anything, says Timothy Bredy, associate professor at the University of Queenslands Brain Institute.

But when researchers began to explore these regions, they realized that most of the genome is active and transcribed.

Using a powerful new sequencing approach, Bredys team identified 433 long noncoding RNAs from relatively unknown regions of the human genome.

The technology is a really interesting way to zero in on sites within the genome that would otherwise be masked, Bredy says. Its like harnessing the power of the Hubble Telescope to peer into the unknown of the brain.

A new gene, which the researchers labeled ADRAM, was found to not only act as a scaffold for molecules inside the cell, but also helped coordinate the formation of fear-extinction memory.

Until now, there have been no studies devoted to understanding these genes, or how they might influence brain function in the context of learning and memory.

Our findings suggest that long noncoding RNAs provide a bridge, linking dynamic environmental signals with the mechanisms that control the way our brains respond to fear, Bredy says.

With this new understanding of gene activity, we can now work towards developing tools to selectively target long noncoding RNAs in the brain that directly modify memory, and hopefully, develop a new therapy for PTSD and phobia.

The study appears in Cell Reports.

The Brain & Behaviour Research Foundation (NARSAD), the National Institutes of Health, the Australian Research Council, and the Westpac Bicentennial Foundation funded the work.

Source: University of Queensland

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Junk DNA may rein in memories tied to fear - Futurity: Research News

Oscar-nominated Cambodian-French director Rithy Panh has a vivid memory of how he first encountered filmmaking. As a young man, Panh had been studying carpentry in Paris and dabbling in painting. He had moved to France after his family had suffered horrific experiences under the Khmer Rouge in Cambodia.

One of his friends was making a short film inspired by Alfred Hitchcock and had asked Panh to give him a hand. This was just for fun. Panh helped with the lighting and other chores. Then, one day, the friends father gave him three cartridges of three minute each, contact chrome Super 8.

Panh used the film to make a short comedy (very funny), still his only foray into that genre. He went on to study at renowned French film school, IDHEC. At the time, most of the young filmmakers in my generation, in my school, liked fiction films - the Nouvelle Vague, Almodovar, John Cassavetes or John Ford.

But Panhs tastes were different. He was drawn to the work of thee Russian directors Andrei Tarkovsky and Alexei Guerman and to the Neo-Realists. And I very much liked documentary films.

He was one of the few students who wanted to make documentary. Even today, when you go to the Oscars, you have one award for documentary film and for fiction film you have best director, best film, best lighting etcits like cinema doesnt want us to be part of the family.

Since those film school days, Panh has achieved huge success in a series of documentaries which have dealt with the Khmer Rouge genocide and its aftermath. His very first feature documentary Site 2 in 1989, about a refugee camp on the Cambodian-Thai border, won an award at the Festival of Amiens. He also picked the top prize for Un Certain Regard in Cannes with The Missing Picture in 2013, which secured an Oscar nomination.

For several years, Panh has combined his own filmmaking with his work teaching in Cambodia and at the DFIs documentary lab in Doha.

Its something that keeps me close to the young generation, the director says of his mentoring work. I always take some time in my life to train young people who come from different countriesits very important for our society now, especially when you are from a country like Cambodia, where you come across many tragedies, you need art to rebuild your identity and social cohesion. Its the same when I move abroad to teach. At the Doha Film Institute, for example, many people come from Palestine or come from Yemen.

Panhs approach with rising filmmakers is straightforward. He encourages them to learn film grammar and to use technique but the most important thing is to make them feel free.

He sends the students copious amounts of material to study: paintings (from Jackson Pollock to Goya) and photographs as well as films.

Most of the time, the people have talent but not yet a cultural background, especially people from poor countries, he says. They dont have the possibility to watch films or go to museums or to read books etc. We need to give them the [cultural] background, the cinematographic background. Afterwards, we can talk about the project.

Panhs most recent feature, Everything Will Be OK, screened in competition at the Berlinale earlier this year, winning a Silver Bear. It is a documentary about the rise of totalitarianism which uses models of animals, archive footage and references to cinema history. As he said in his Berlin press conference, democracy today is really fragile, more fragile than ever before. I was wondering about the role of cinema in these times. What can we do? What should we do?

He acknowledges film cant change the world. Instead, he believes it serves a similar purpose to poetry where you read a few lines and it changes your day. You feel betteror even when you feel more sad, its OK because it reveals something in you.

And now Panh is waiting for his next project to reveal itself. I want to make a retreat to the forest to find some silence.

He admits he is spending many hours on the NASA website looking at images of the galaxy and pictures taken through the Hubble telescope. We are only dust. Maybe I need to feel myself as nothingmaybe it is a good way for me to be normal.

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Rithy Panh on the joy he finds in mentoring rising filmmakers - Screen International

Deep within the Andromeda constellation, some 320 million light-years away, two galaxies are consumed by a gravitationally bound dance, and the Hubble Space Telescope has just photographed the action in extraordinary three-dimensional detail.

The two dancers are the smaller polar-ring galaxy IC 1559 (top) and the larger spiral galaxy NGC 169 (bottom). Collectively, they are known as Arp 282, as designated in Halton Arp's Atlas of Peculiar Galaxies.

It's not unusual for galaxies to interact gravitationally. "Astronomers now accept that an important aspect of how galaxies evolve is the way they interact with one another," NASA officials wrote in a statement. "Galaxies can merge, collide, or brush past one another each interaction significantly affecting their shapes and structures."

Related: The best Hubble Space Telescope images of all time!

It is difficult, however, to photograph such an interaction in a way that clearly demonstrates its movement within three-dimensional space. In the case of Arp 282, Hubble was at the perfect angle to capture the strands of stars, dust and gas being pulled by tidal forces from one system to the other.

If Arp 282 were tilted at a different angle, the telescope might never have been able to image the dance so clearly. Imagine looking at this scene through the bottom of NGC 169, for example it'd be unlikely to see the distortion of the two galaxies as crisply.

It's also fortunate that the instrument took this image in visible light. Both IC 1559 and NGC 169 have active galactic nuclei (AGN), meaning their cores are "monumentally energetic," per NASA. In other words, they have supermassive black holes expelling vast quantities of energy in the full range of the electromagnetic spectrum.

"If the image revealed the full emission of both AGNs," NASA officials wrote, "their brilliance would obscure the beautifully detailed tidal interactions we see in this image."

Follow Stefanie Waldek on Twitter @StefanieWaldek. Follow us on Twitter @Spacedotcom and on Facebook.

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Hubble telescope was at the perfect angle to capture this nearly impossible shot of two 'dancing galaxies' - Space.com

At the moment, astronomers and astrophiles across the globe are just beginning to receive some of the first highly anticipated images from the James Webb Space Telescope. The short film My God, Its Full of Stars invites viewers to celebrate its predecessor in peering deeper into the cosmos than humanity ever has before the Hubble Space Telescope as well as some of the human stories behind it. Created to accompany an essay by Maria Popova as part of the The Marginalians Universe in Verse series, the animation adapts a poem by the former US Poet Laureate Tracy K Smith, whose father worked on the Hubble as one of NASAs first Black engineers. Pairing Smiths words with meticulously crafted visuals from the Brazilian animation director Daniel Brunson, the piece is a wondrous ode to our desire to know the Universe. Reflecting on the project in her essay, Popova writes:

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A poet's ode to the Hubble Telescope and to her father, who helped to build it - Aeon

Paul M. Sutteris an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of "Ask a Spaceman" and "Space Radio," and author of "How to Die in Space."

Globular clusters are like astronomical coelacanths mysterious living fossils. These densely packed collections of ancient stars may hold the ultimate secrets to the formation of galaxies.

On a clear, dark night, you can see the globular cluster Omega Centauri with the naked eye. It looks like a midrange, typical star, so much so that it's been listed in star catalogs since antiquity. But once astronomers looked at the object through a telescope, they discovered that it wasn't a single star at all but rather one of the largest globular clusters a small, round, dense collection of millions of stars.

That roundness is what separates globular clusters from other kinds of star clusters (and gives them their name, from the Latin for "small sphere"). They are large enough and contain enough stars that there's enough gravity to pull them into spherical shapes.

And that's about the last thing that makes sense about globular clusters.

Related: Vibrant globular cluster sparkles in new Hubble telescope photo

Globular clusters are freakishly old. Of the approximately 150 of them within the Milky Way, the very youngest are no less than 8 billion years old, while the oldest are almost 12 billion years old. They haven't had new rounds of star formation in billions of years, so what remains within them are either remnants (white dwarfs, black holes, etc.) or small, dim, red stars. Whatever caused them to form happened a long, long time ago, and they simply haven't changed much in all those eons since.

In fact, Omega Centauri is one of the oldest things you can see with the naked eye. When the solar system formed, that globular cluster was already fantastically ancient.

The globular clusters are incredibly dense, too. In the deepest parts of their cores, stars cram together up to a thousand times more densely than in the solar neighborhood. They are so tightly packed that planets are almost impossible; there are just too many close calls and near misses for a planetary system to survive long.

In the past few decades, astronomers have noticed that there are very roughly two distinct kinds of globular clusters: young ones and old ones.

Of course, "young" here is a relative term. These younger ones tend to be 8 billion to 10 billion years old. They also tend to hang out closer to the central bulge of the Milky Way and have far more metals than the other globular clusters. In astronomy jargon, "metals" means any element other than hydrogen and helium. Those heavier elements are forged inside stars through nuclear fusion, and in a normal galaxy, continued rounds of star formation and star destruction continually enrich the galaxies. But because all of these globular clusters were born at roughly the same time, with no new star formation since then, the presence of metals means that the globular clusters had to form from an already-metal-rich environment.

The other, older globular clusters are more in the 10 billion to 12 billion-year-old range. These are far more common; about two-thirds of the globular clusters in the Milky Way are from this population. They tend to be farther from the galactic center, have all sorts of random orbits and be almost metal-free.

Astronomers suspect that the young globular clusters formed with the Milky Way itself 8 billion to 10 billion years ago, while the older ones formed before our galaxy even got going. Those globular clusters probably formed with small, dwarf galaxies that got demolished by the Milky Way. The dwarf galaxies were torn apart, but the small, dense globular clusters managed to survive to the present day (nevertheless forced to orbit the same galaxy that destroyed their parents).

OK, great; we have two kinds of globular clusters. But how did they form in the first place?

The biggest clue to the origins of globular clusters is that they have no dark matter. Measurements of their mass using different techniques (adding up all the sources of light, calculating the gravity needed to keep them round, and so on) all add up to the same number, with no need for a hidden, unseen component. This means that globular clusters in the present day are entirely unlike galaxies. It's a little challenging to come up with a definition of "galaxy," but since almost all galaxies are made of at least 80% dark matter, you must include that fact somehow.

Because globular clusters lack dark matter, it means we can't just treat them as minigalaxies at least, in the present day. It's possible that dark matter played a role in forming globular clusters, the same way it did for galaxy formation, just on a much smaller scale. But perhaps the dark matter in the globular clusters dispersed through interactions with parent galaxies, leaving behind the clump of dead and decaying stars.

Or maybe dark matter never played a role. Maybe instead of being failed galaxies, globular clusters are super-successful star clusters. Take the same process that forms any other cluster (a large cloud of gas and dust collapsing and splintering into a shower of stars) and ramp it up to 11, and you get hundreds of thousands or millions of stars in a single go. That intense flash of star formation shoved away all the remaining gas, leaving the globular cluster intact but functionally dead.

To date, astronomers aren't exactly sure which scenario is more likely. Either way, globular clusters are intriguing because they are so obviously linked to galaxy formation and astronomers aren't exactly sure how galaxies form and evolve. By studying these giant time capsules, we hope to peer into our own ancient past and unravel the ultimate mysteries of how our own galaxy came to be.

Learn more by listening to the "Ask a Spaceman" podcast, available oniTunesand askaspaceman.com. Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutter and facebook.com/PaulMattSutter. Follow us on Twitter @Spacedotcom and on Facebook.

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Mysterious globular clusters could unlock the secrets of galaxy formation - Space.com