Category Archives: Galaxies

Universe Contains More Galaxies Than Thought

Galaxies all Over UsJust how large is the universe? Far larger than initially thought. Astronomers have discovered that there are at least 10 times as many galaxies in the universe.

Using data from the NASA/ESA Hubble Space Telescopes, astronomers have been able to perform an accurate census of the number of galaxies in the universe. In the mid-1990s, it was estimated that the observable universe contained between 100 to 200 billion galaxies. However, the latest data and images gathered have revised that number upwards significantly to the tune of over two trillion galaxies.

The team of researchers used deep-space images from the Hubble and a number of sources of data to make accurate measurements of the number of galaxies that existed at different times in the universe’s history. They determined that approximately 90% of galaxies are too faint and far away to be seen.

“It boggles the mind that over 90% of the galaxies in the Universe have yet to be studied,” lead researcher Christopher Conselice of the University of Nottingham, UK, said in a statement. “Who knows what interesting properties we will find when we observe these galaxies with the next generation of telescopes.”

In order to observe the galaxies, the team of researchers had to compile data going back 13 billion years ago because they were studying parts of the universe that were up to 13 billion light-years away. This allowed them to observe the evolution of the universe and conclude that the early universe contained more galaxies than it does today. Some of the small dwarf galaxies merged together to form larger galaxies as time went by.

“This gives us a verification of the so-called top-down formation of structure in the Universe,” Conselice said.

The confirmation that the number of galaxies has been decreasing as time has progressed also helps to explain why the night sky is so dark. There was a theory that the night sky should be permanently light given that the universe is filled with an infinite number of stars. However, this theory was created before the understanding of the universe’s dynamic nature.

“This is very surprising as we know that, over the 13.7 billion years of cosmic evolution since the Big Bang, galaxies have been growing through star formation and mergers with other galaxies,” Conselice said in a separate statement. “Finding more galaxies in the past implies that significant evolution must have occurred to reduce their number through the extensive merging of systems.”

Just think, there could have been a planet with intelligent life on it similar to ours in a galaxy 13 billion light-years away (that’s 13 billion years ago) and we will never know!

New Galaxy Type Discovered – Super Spirals

Super Spiral GalaxyA group of scientists led by Dr. Patrick Ogle from the California Institute of Technology recently discovered a new type of galaxy called a super spiral.

These super spirals are incredibly bright, shining from 8 to 14 times the brightness of our own Milky Way Galaxy. Not only that, they are extremely massive. The diameter of some super spiral galaxies discovered reaches up to 437,000 light years with solar masses of up to 340 billion. Super spirals are also creating stars at a very high rate, up to 30 times that of our Milky Way. Extreme amounts of UV and mid-IR light are also given off.

Dr. Ogle and his team discovered the super spirals by pure chance as they searched for extremely luminous and large galaxies in the NASA/IPAC Extragalactic Database (NED). Dr. George Helou, the teams leader has said, “Remarkably, the finding of super spiral galaxies came out of purely analyzing the contents of the NED database, thus reaping the benefits of the careful, systematic merging of data from many sources on the same galaxies.”

The astronomers thought that older, massive galaxies known as ellipticals would be dominating their search within NED but instead the team discovered was surprised with the new category of galaxies. The sample size of around 800,000 galaxies about 3.5 billion light-years from Earth, had a mere 53 of the brightest galaxies that showed to have a spiral shape rather than an elliptical one. After the team cross checked the distances to the spirals and saw that none were nearby, they realized even the closest spirals lay 1.2 billion light-years away.

The largest and brightest super spiral galaxy discovered, named SDSS J094700.08+254045.7, is a starry disk with spiral arms that stretch out about 320,000 light-years across. This is more than three times the full width of our Milky Way Galaxy.

The only clue we have about the origin of these super spiral galaxies is that 4 out of the 53 seen by the scientists contain two galactic nuclei, instead of the usual one. The scientists explains that double nuclei are a telltale sign of two galaxies having just merged together. Traditionally, mergers of spiral galaxies were believe to be destined to become bloated, elliptical galaxies.

The team is still speculating however. that a special merger involving two, regular gas-rich spiral galaxies could see their combined gases settle down into a new, larger stellar disk, which would be a super spiral.

Dr. Ogle, the lead author of the paper on super spirals published in the Astrophysical Journal has that that “Super spirals could fundamentally change our understanding of the formation and evolution of the most massive galaxies.”

Farthest Galaxy EGS-ZS8-1

farthest-galaxy-egs-zs8
The farthest galaxy known to man is egs-zs8-1. Photo by Hubble Telescope. Credit: NASA, ESA, P. Oesch and I. Momcheva (Yale University), and the 3D-HST and HUDF09/XDF teams.

The furthest galaxy known so far is EGS-ZS8-1, which is 13.1 billion light years from Earth.

That means that the galaxy is very close to the beginning of the Big Bang in reference to time.

 

 

In the photo above, EGS-ZS8-1 is displayed via the Hubble Telescope. What’s interesting in this image is that every object shown here is also a galaxy.

Time and light are consistent entities that help scientists determine the distance of objects in outer space.

For example, since light is a constant (186,000 miles / second), by use of mathematical equations, astronomers can determine the approximate distance an object is from Earth. One method is by using the spectroscopic redshift, more specifically, it is called the cosmological redshift.

Since light bends in the universe, the further the object is from Earth, the more there will be a shift in the electromagnetic spectrum towards the red end. Many distant objects show a shifting towards the red spectrum and EGS-ZS8-1 has shown the greatest shift of them all.

Also, wavelength plays a role, as the longer the wavelength, the more of a red shift there will be. The formula is the following, where frequency = f, wavelength = λ and the speed of light = c:

Frequency Formula

Using these methods, the distance of this galaxy was confirmed by the WM Kirk observatory in California and as a result, we could get a very good picture of what early galaxies looked like near the beginning of the Big Bang, which are quite different from the more mature galaxies we see today.

High-redshift_galaxy_candidates_in_the_Hubble_Ultra_Deep_Field_2012
This image shows the Hubble Ultra Deep Field 2012 revealed for the first time a population of distant galaxies at redshifts between 9 and 12, including the most distant object observed to date. These galaxies are shown at the top of the image and their locations are pinpointed in the main image.

Since the universe is thought to be 13.8 billion years old , we would be looking at a galaxy that is only 700 million years away from the beginning of time. A baby compared to some other galaxies that are only 5 and 10 billion years old.

Finding this young entity, which is in the constellation Bootes, scientist can compute many variables that can bring our knowledge one step closer to determining how it all began. And what a miracle that would be!

 

Ancient Myths and the Milky Way

The Milky Way is a colossal cluster of stars, dust, gas and other elements that are held together in outer space via gravitational pull and our Milky Way galaxy is no exception to the laws of gravity, as are any of the countless galaxies present in the universe.

Democritus Greek philosopher
Greek philosopher Democritus said the Milky Way is actually made of stars

It was Democritus, an ancient Greek philosopher who first suggested that the Milky Way is actually made of stars, contrary to the popular belief (discussed below). Democritus lived from 460 to 370 B.C. Later in 1610, Galileo Galilei first identified and resolved the mystery of the peculiar band of light. He used his telescope to establish that it is actually a group of several individual stars.

For those who find the extraterrestrial bodies fascinating, the Milky Way has a lot to offer. For now, we are focusing on ancient myths associated to this celestial body.

The Ancient Myths

The Milky Way is more than just a galaxy. It has held symbolic importance in the past for myths originating in different parts of the world. We are detailing the most popular ones below:

The Silver River

In a collective Eastern Asian myth (Korea, China, Japan), the Milky Way was called the Silver River. According to the myth the river was placed by the gods in the heavens to keep their weaver (she made their clothes) and her lover, the herdsman from meeting each other. Certain renditions of the myth consider the stars Altair and Vega to be the separated lovers who meet on the seventh night of the seventh month when the crows and magpies form a bridge for them over the galactic river.  Qi Xi (the Seventh Night) is the day that celebrates their union every year.

Hera’s Milk

‘Galaxy’ is a Greek word. It means ‘milk’. The origin of Milky Way can be dated back to the ancient Greeks, who believed that the Milky Way was formed when Hera, while suckling Heracles spilled her milk. The same was also believed to be the path to Mount Olympus – often known as the path of ruin created by the sun god Helios’ chariot.  

The Romans named the galaxy the Milky Road. Now you know where the idea of milk is coming from!

Akasa Ganga

In the Hindu mythology, the planets and the stars present in the universe are compared to a dolphin swimming in the water. The Milky Way in this myth is considered to be the dolphin’s abdomen and is called the Akasa Ganga which translates to the Ganges of the heavens. The Ganges for the Hindus is a holy river.

In another myth, Vishnu is narrated to be meditating on the surface of the sea with his companion Lakshmi in the ‘Sea of Milk’.

There are several other myths originating from different parts of the world that revolve around the Milky Way. Some narrated it as the ‘rope and anchor’ while others considered it to be the ‘road of the warriors’. Are there any other myths related to the Milky Way that you’re familiar with? Maybe something your grandma narrated to you when you asked for bedtime stories.

Andromeda – Our Nearest Spiral Galaxy

The spiral galaxy of Andromeda
Andromeda Galaxy. 220,000 light years across, containing 10 trillion stars

What was the subject of the popular heated debate between ace astronomers, Heber Curtis and Harlow Shapley? – The Andromeda galaxy!

Back in 1920, Shapley believed that the Pinwheel and the Andromeda galaxies were actually nebulae found in the Milky Way. Curtis believed that this wasn’t the case, based on the argument that the Andromeda galaxy is on a multi-million light-year distance from our Milky Way. It was later established through the work of Henrietta Leavitt, Edwin Hubble, and others that Curtis indeed was right.

Over the years, a lot astronomers have researched Andromeda with some of the findings listed below..

Once a Nebula?

Long before the actual expanse of the universe was realized, the rim of the Milky Way was considered to be the boundary of outer space. Within those boundaries the fuzzy blur visible in the sky (the Andromeda) was believed to be a cluster of cosmic dust clouds and forming stars. The galaxy was originally named the Great Andromeda Nebula until the powerful telescopes of the 20th century proved otherwise.  

It Can Be Seen From Earth

This mammoth, dazzling galaxy is at least at a 2.5 million light year distance away from us. However, if you find a clear night sky (the pollution levels need to be down too) you can see the galaxy with the naked eye. It would appear as a scattered haze. Grab a pair of good binoculars and you can clearly witness the central region of the galaxy. A large powerful telescope will leave you in awe of the spectacular view of Andromeda.

It’s Gigantic

The galaxy has a diameter stretched across almost 220,000 light years. A colossal structure that seems longer that the full moon at night and is actually 2.5 times longer in length than the entire Milky Way. It is farther than any other star visible from earth, yet it can still be seen with the naked eye. 

It is believed that the Milky Way is the most immense body in the Local Group (a galactic group based on more than 54 galaxies), but the Andromeda takes the cake when it comes to being more voluminous. It contains trillions of stars, twice as much as the ones in our galaxy. It was the Spritzer Space Telescope that made this observation.

We’ve Known It for a Lifetime

The Andromeda galaxy being clearly visible in the night sky has been constantly scrutinized, observed, and studied by astronomers for multiple decades. The galaxy spawned about 10 billion years ago when several smaller protogalaxies merged together. About some 8 billion years ago it collided head on with another galaxy that led to the formation of the giant that is Andromeda today.

Now here’s the fun part.  Andromeda is moving towards our galaxy. And it’s not just moving – it’s actually on a collision course! 

Let that sink in. Andromeda and the Milky Way are both moving towards each other at a speed of 120 kilometers per second. But here’s the catch: at this rate it’ll take around 4 billion years for the galaxies to collide!

 

Galaxy Clusters

Galaxy ClustersGalaxy clusters are considered the largest array of objects that are grouped together by gravity. They are the densest part of the large-scale structure of the universe.

In the photo above, there are over 4000 galaxies shown, called Abell, after the scientist who discovered them in 1958, George O. Abell.  Some are hundreds of millions of light years apart from each other. Considering this is an image of clusters of galaxies, hundreds in each cluster, and when a typical galaxy contains between 100 – 200 billion stars with average diameters of 100,000 light years each, this is quite mind blowing.

Our Milky Way Galaxy is part of a cluster called the Local Group or Local Cluster and consists of over 54 galaxies. All clusters have a gravitational center and ours is located between the Milky Way and the Andromeda galaxy. 54 galaxies may sound extraordinary, but that is minuscule when considering that there are over 100 billion galaxies in the known universe.

For galaxy clusters, we measure their distances in units of parsecs. A distance of one million parsecs is commonly denoted by megaparsec (Mpc).

A parsec represents 1 degree of the angle that is created for 1 AU. If we draw a line of 1 AU (which is the distance between Earth and the Sun), then draw a line from each point (E and S), the point at which the two lines meet (D), we create a triangle of 1 arc second,  so the distance between the Earth point and the point at which the lines meet is 1 parsec.

1 Parsec = 206,264.81 astronomical units
        Dimensions not in scale.

1 Parsec is equal to the distance D from the Earth E by an angle of 1 arc second, which equates to 206,264.81 astronomical units (AU).

1 parsec = 206,264.81 astronomical units (AU) = 3.26 light years ~ 19 trillion miles.

There is an easy conversion utility for AU and parsecs here.

Our Local Group (of galaxies) has a diameter of 3.1 megaparsecs, which is, 3.1 x 1,000,000 parsecs in length or 3.1 mp * 3.26 ly.

 

Galaxies

andromeda galaxy
Andromeda Galaxy

Galaxies are created from dust clouds that are floating random in space and as they come near each other, they ‘clump’ together. As they continue to clump together, they build up ‘matter’ and as this matter builds, gravity is created.

When gravity builds, it attracts more dust and matter to the point that stars and planets are created, resulting in solar systems. All staying in place by an invisible force in the center of the galaxy, called a black hole, where the creation of the galaxy all began.

Our Milky Way galaxy is over 100,000 light years long, so to put this in perspective, if you traveled at the speed of light it would take you 100,000 years to go from one end to the other.

There are over 100,000,000 galaxies in the universe. All consisting of hundreds of millions of stars and solar systems. Some are over 13 billion light years from Earth, so if you were to see microbes (early life) on a planet in a solar system that is in a galaxy that is 13 billion light years from here, you are looking at them 13 billion years ago.

No doubt that civilization has advanced way beyond anything we can imagine. What’s more, that galaxy may not even be in existence anymore, along with the intelligent life that was on it. The galaxy could have collided with another galaxy forming a new larger galaxy or could have simply reached its life cycle and dispersed back into dust and random matter due to other universal forces at work.
It is estimated that our Milky Way galaxy will collide with our neighboring Andromeda galaxy in about 4.5 billion years. Are you ready?

Ten Astronomy Facts That Will Give You Shivers

Astronaut in Space
There are many among us whose interest in the subject of Astronomy went only as far as making Styrofoam models in grade school. Since then, with all the technological advances, scientists have been able to reveal various shocking discoveries about our cosmic neighbors.

Interestingly, space is so very big that each discovery will can no doubt be fascinating. From the times of Galileo to the present day, astronomers each day bring new intelligence about space. Let’s learn some of the most intriguing facts about outer space:

The Vampire Stars:

Blue stragglers are the kind of stars that consume energy, hydrogen fuel to be more specific, from their ancient neighbors. Sucking energy is not their only similarity they have with vampires; they also stay young and shine bluer than the other stars soon after their vampiric feast.

Pluto Is Tiny:

We all know that Pluto was the tiniest planet, but did we know that it was even smaller than the USA? No doubt it has reduced in rank and is now called a Dwarf Planet.

Water in Space:

We all know that space has no gravity and everything just floats around with no point of destination. What we didn’t know is that if we throw a glass of water in space, it will take a spherical shape.

Eerily Quiet:

In all the movies about the universe and in our own imagination of outer space, we never would have imagined this one, but space is extremely and eerily quiet. Since sound waves need an atmosphere to be heard and space has none, you can safely say that the whole of outer space might as well collapse and it won’t even make a sound to our ears.

How Far?

The universe is so large that it is beyond comprehension. One example is the galaxy MACS0647-JD, which is only 420 million years old; that is, it was created 420 million years after the Big Bang and in universal terms, that is quite early. It would be equivalent to the age of a person at six months in the mother’s womb. What’s even more incomprehensible is that we see this galaxy (through the Hubble Telescope) as it was 13.3 billion years ago, since it takes light 13.3 billion years for it’s image to reach us; so, if we were to actually see any forms of life on the planets in this galaxy, we would be looking at these civilizations as they were 13.3 billion years ago. No doubt they are nothing but bands of dust floating in the universe, along with MACS0647-JD.

The Lucky Apollo:

Know how we all say that Neil Armstrong was the first man to land on the moon and left his mark there? We would never have thought that the meaning is quite literal. Since there is no water, air or living organisms on the moon, the footprints of Apollo’s astronauts and their rover’s mark will stay there for at least another 100 million years.

The Outer Space Scent:

Ever wondered what space must smell like? The astronomers who return from their strolls in outer space have been known to report that their gear smells like welding fumes, seared steak and hot metal. The smell of the dying stars perhaps?

Eau De Milky Way:

While the outer space smells like metal and fumes, the Milky Way is a whole another story. The middle of the Milky Way is known to smell like raspberries and rum.

Another Earth Maybe?

In our solar system, we are the only life forms in it, but the last couple of years of research have revealed various other solar systems like ours. So does that mean that there is another earth out there? The search is still going strong and astronomers believe there is.

Well, if they do find another earth like ours, we sure hope it is more peaceful than this one.

Active Galaxies

ActiveGalaxyWith ingenious devices scanning the heavens in spectrums beyond the visible, many marvels have been revealed in recent years, and some of the most awesome are the aptly named active galaxies.

Normal galaxies  make up about 90% of all galaxies in the universe., but are a class of galaxies that are referred to as active galaxies.  There are two main differences between active galaxies and normal galaxies:

  • Total Luminosity – An active galaxy has a larger total luminosity (is the total amount of energy emitted by an astronomical object per unit time) than a normal galaxy of the same type.
  • Spectrum – The luminosity from a normal galaxy is basically equal to the sum of the luminosities of its stars. However, the spectrum of an active galaxy shows that it gives off a lot of nonsteller radiation that is coming from a source other than the stars in the galaxy.

Radio galaxies spew jets of matter many light-years long from a relatively small nucleus called an AGN, an active galactic nucleus, brightly lit in X-ray and radio frequencies even though they may be optically dim. These radio galaxies show nuclear and extended radio emissions. They are usually elliptical and show two lobes of radio frequency emission that are aligned with the jets observed in the visible spectrum and may extend for millions of light years. These galaxies can live for a few hundred thousand years or up to a few million.

Seyfert galaxies are spinning discs with intensely active highly ionized nuclei. They were the earliest distinct class of AGN to be identified. They show optical range nuclear continuum emission, narrow and occasionally broad emission lines. They also occasionally show strong nuclear X-Ray emission including a weak small scale radio jet.

Elliptical N-galaxies have nuclei that vary in intensity, and a subspecies, known as BL Lacertae (BL Lac) objects, they are also called “Blazers” because they have active nuclei that are even more wildly fluctuating. This is probably as a result of being head-on into a jet.

Quasars (quasi-stellar radio sources) are a hundred to a thousand times brighter than normal galaxies and emit vast quantities of radiation. It is thought that they are the bright hearts of active galaxies, powered by supermassive black holes. With very high redshifts suggesting a very great distance, quasars are thought to be young galaxies from the earlier ages of our universe.

However, there are puzzles. Twin quasars have been observed on each side of younger, lower redshift active galaxies, suggesting that they might be connected, hence at the same distance. This raises the possibility that redshifts are not always caused by recession speed and so they might not be such a reliable measures of distance, although the effect could be caused by gravitational lensing. Additionally, some jets have extreme redshifts, appearing to be moving faster than light, breaking the cosmic speed limit. These seemingly super luminal emissions may be due to serious space-time distortions in the high energy zones dominated by the huge black holes from which they have burst.

A View of Colliding Galaxies

Colliding GalaxiesSeveral powerful telescopes, including the Hubble, have managed to capture an event that occurred when the universe was half its current age: two galaxies colliding. This ancient event has been hidden to acus until now, because the galaxies were situated behind a much larger galaxy blocking our view.

However, the large galaxy in question was so big that it acts like a magnifying glass for the space behind it. This and other “lensing galaxies” are so large, they bend and distort light from smaller galaxies behind them, allowing astronomers to be able to see what would normally be obscured from view as long as the lensing galaxy and the one behind it are precisely aligned.

“These chance alignments are quite rare and tend to be hard to identify, but, recent studies have shown that by observing at far-infrared and millimeter wavelengths we can find these cases much more efficiently,” Hugo Messias of the Universidad de Concepcion n Chile and the Centro de Astronomia e Astrofisica da Universidade de Lisboa in Portugal, said in a statement.

At the end of July, astronomers found the farthest lensing galaxy yet, so distant that its light has taken 9.6 billion years to reach Earth. The magnifying properties of the galaxy allows us to compare local galaxies with much more remote ones and events that occurred when the Universe was significantly younger.

The above image was created combining multiple images from the Hubble Space Telescope and the Keck-II telescope at the Keck Observatory on Hawaii. These two galaxies, known collectively as H1429-0028, is creating more than 400 solar masses of gas into new stars each year. In comparison, the Antennae Galaxies, a similar phenomenon of colliding galaxies occurring much closer to us, is only forming stars with a total rate of 10 times the mass of the Sun.

Since the lensing galaxy is so far away, these events happened more than 9.6 billion years in the past. In real time, both the lensing galaxy and the colliding galaxies probably looks vastly different.