X-Ray Transients

The universe is a harsh place, and that becomes obvious when you start detecting all the forms of radiation that comes from various sources. Space, in itself, is not very conducive to life, but when you have huge amounts of X-rays randomly traveling through the solar systems, you do sometimes wonder how life developed anywhere. X-rays transients are just one reason why space travel is a lot harder than many people think.

What Are X-rays Transients?

They are X-rays that periodically pass through the solar system, and then they just disappear.

Detecting these has only recently been possible, thanks to space travel. The atmosphere absorbs X-rays, so we can’t detect them on the surface of the Earth.

Fortunately, the use of essentially ICBMs with an X-ray detector strapped to them in the 1960s became a cheap method of trying to detect X-rays and getting a baseline reading of the background X-ray readings. This method detected the first X-ray transient source: Cen X-2.

Nobody knew what it was, and because there was a four-year gap between all three readings, the source remains undiscovered. What this did do was pave the way for the discovery of other X-ray transients, including Cen X-4.

These ICBM launches eventually gave way to Vela satellites, which were ostensibly for nuclear test monitoring. However, they also carried X-ray detectors, which meant that they could be used for X-ray transient detection.

Eventually, sufficient X-ray transient sources were discovered that they were put in their own class. But what were they?

Binary Stars Hold the Answer

As the data was released and declassified — albeit very slowly, as the satellites held militarily sensitive information — astrophysicists were able to identify the areas where X-ray transients occurred: They all appeared to be binary stars.

It was clear that the binary stars were producing these X-rays, but why?

It turns out that these binary systems typically involve a functioning star, such as a main-sequence star or a red giant, and either a neutron star or a black hole. In some cases, it can involve a nova and a black hole.

It seems likely that the two stars have elliptical orbits, where one star passes through the accretion disc of the other at regular intervals. The denser star gobbles up hydrogen and helium, creating a burst of X-rays and gamma rays from the sudden increase in fusible elements. The other star passes through and resumes its journey orbiting around the denser star, albeit with significantly less mass.

In this system, you get low-mass and high-mass X-ray bursters, depending on the mass of the star that is being scavenged by the neutron star or black hole. You also get soft X-ray transients, which exhibit less violent X-ray outputs compared to the bursters. There are also supergiant X-ray transients, which exhibit their own particular set of characteristics.

Other Sources of X-ray Transients

Our own sun can produce X-rays periodically, and this can lead to X-ray transients. The sun’s overall output is factored into the background radiation level, so when it produces a major mass ejection, the X-rays within the solar system suddenly increases. Because it is so close, it can have a significant impact on the earth, creating geomagnetic storms.

Jupiter can also create X-ray transients, and these can be detected quite easily from Earth. However, these are a particular sort of X-rays, so they can be differentiated from ones produced by binary stars.

X-ray transients are a particular space hazard, but they do not generally affect intra-solar-system travel. Should we wish to go further, it’s essential that we understand how these X-rays are produced to ensure we can avoid or compensate for them.

Rings Around Planets

Rings Around Planets

No, these planets didn’t listen to Beyonce and get inspired to “put a ring on it”, nor are these rings anything like you would get at your local jewelry shop. Rings around planets are actually made up of little pieces of rock and ice. Comets, asteroids, and other massive objects that fly by certain planets are obliterated by the strength of that planet’s gravity. 

The act of a planet’s gravity tearing apart a large object is known as the Roche Limit. The Roche Limit is a point in the gravitational pull that objects get pulled apart so that they don’t reform back into a larger, hazardous object. Essentially, rings are a consequence of natural, planetary protection!

You can think about these rings as a composition of thousands and thousands of moon-like objects that don’t have the power to clump back up into larger formations. Each of these tiny ice and rock particles maintain their individual orbits around the planet that they are near. It is only from far away that they appear to be one singular ring.

When Were Rings Around Planets Discovered?

Thanks to the fact that Saturn is a massive planet, it is one of the most easily identifiable targets for astronomers. This is especially true because it has a unique ring system that has been a fascinating point of reference for astronomers over the past few hundred years. Galileo Galilei was the first man to ever observe the rings of Saturn in the year 1610. At first, he thought that the rings were large moons that were sat on both sides of the planet. After continuing to observe it for many years, he finally realized that these rings would change shape and size as the Earth rotated.

In 1655, an astronomer by the name of Christiaan Huygens guessed that the bodies circulating Saturn were actually solid rings. About five years later, the idea that they were actually a large composition of smaller, singular bodies popped up. It wasn’t until the Pioneer 11 passed through the ring of Saturn that we confirmed that idea.

Biggest Ring Known To Man

Saturn may have the largest and most impressive rings in our solar system, though they aren’t the largest in the universe by a long shot. A team of astronomers just recently discovered a massive ring system around a planet far outside of our solar system. They call this planet J1407b.

This ring system is enormous, about 200 times heavier than the rings of Saturn. The planet is about 434 light years away from our planet and was the very first of these large, ring-type planets found outside of our own Solar System. The ring system is said to be made up of about 30 different rings, each of which is over 10 million km in diameter. 

Fun Facts About Rings Around Planets

The ring system of Jupiter is actually made up of four main components. There is thicker, inner torus known as the halo ring, which is made of millions of small particles. Next up is the main ring, which may be one of the brightest, though is very thin. At the outside lie two very thick, wide, and faint rings known as gossamer rings. These rings are made up of materials that come from the moons of Jupiter, Amalthea, and Thebe. This is why scientists refer to these rings as the Amalthea Ring and the Thebe Ring.

Saturn is made up of 12 different rings, though they are only divided into two categories. It is the biggest ring system that we know of in our solar system. There are a large variety of gaps in the ring where the density of the particles orbiting is heavily reduced. These gaps are typically caused by the Moons of Saturn entering the gaps and creating odd resonances that clear the space around them.

The rings of Neptune were not discovered until 1989 when the Voyager 2 passed by them in a flyby. As of now, we have observed about six different rings in the system, though each is fairly faint. These rings are incredibly dark, which leads scientists to believe that were processed through different forms of radiation. These rings are very similar to the rings on Uranus, and just like Uranus and Saturn, there are four moons that orbit within the ring system.

How Far Is The Nearest Ring Around A Planet?

The closest set of planetary rings to us happens to be Jupiter’s rings. The rings of Jupiter were not discovered until 1979 when the Voyager 1 spacecraft passed by them. Eventually, NASA’s Galileo spacecraft decided to investigate them more during the early 1990s. These observations led to the conclusion that there were four sets of rings around Jupiter. These rings are about 92,000 kilometers away from the surface of the planet and stretch to about 122,500 kilometers away.

Latest News About Rings Around Planets

Astronomers have detected the very first moon-forming ring around a planet far beyond our solar system. Scientists found one of the first moon-forming rings when they discovered the rings of Jupiter. They expected that they would eventually find these same moon-forming rings in other systems. The planet that they are now analyzing is known as PDS 70 c. It is about the size of Jupiter and is very similar in that it is a gas giant that is orbiting around a small star. The planet is about 370 light-years away from our Earth. The rings were discovered thanks to the ALMA observatory.

What Is An Asteroid?

Asteroid

The first thing that might come to mind when you think of an asteroid floating about in the cosmos is science fiction. It’s pretty easy to picture the Millenium Falcon blowing one to smithereens. With that said, these massive objects are a huge part of our universe, though they are actually quite small in relativity to the rest of the entities in space.

Astronomy describes asteroids as little rock objects in space that orbit around the sun. Though they share the same orbiting characteristics as planets, they are much smaller. There are millions of asteroids within our own solar system, though the majority of them move within the asteroid belt, which is a large region of space between Jupiter and Mars. 

In terms of formation, asteroids have been around for billions of years. They are said to be left over pieces of the inception of our solar system, which came into creation about 4.6 billion years ago after a massive collapse. While most of the material joined forces to create the center of our solar system, aka the sun, as well as most of our planets, there were some leftover portions that hung around without ever joining a larger, planetary mass. 

Not all asteroids are the same. In fact, asteroids are a bit like snowflakes, as we have yet to find even two that are exactly alike. Most asteroids have jagged, irregular shapes, though a lot of people assume that they are all round like planets. Asteroids can be anywhere from hundreds of miles in diameter to the size of a rock on the ground in your backyard. In terms of material, asteroids are typically made out of a variety of different elements, including nickel and iron. Some even have clay!

When Were Asteroids Discovered?

Asteroids were discovered in 1801 by an Italian astronomer and priest named Giuseppe Piazzi. He discovered Ceres, one of the largest asteroids known to man, as it was orbiting on the belt between Jupiter and Mars. Ceres is now classified as a dwarf planet, as it is about a quarter of the mass of every single asteroid in the belt put together. 

The word “asteroid” was not actually the name until 1802, when William Herschel wanted something a bit different to classify them by instead of “minor planets”, which many scientists referred to them at the time. It comes from an old greek phrase that means “star-like”.

Biggest Asteroid Known to Man

It is difficult to classify the largest asteroid, as the three largest ones out there, Ceres, Vesta, and Pallas, are actually classified as protoplanets. This is because they share many of the same characteristics with planets in our solar system. The largest asteroid that resembles other asteroid on the belt is known as Hygiea. This asteroid, much like others on the belt, has an interior that is undifferentiated. While Ceres is the largest by a long shot, the fully ellipsoidal shape technically makes it a dwarf planet.

Asteroid Fun Facts

NASA scientists believe that the only reason we are alive and well on Earth today is because asteroids collided into each other millions of years ago. They say that the origin of life can be accredited to the massive flux of asteroids and comets that smashed into each other, forming the Earth. As comets continued to collide, the small materials that were deposited helped life to form. These collisions helped to deliver water and ice, as well as molecules with carbon bases. 

There are a number of asteroids out in space that scientists believe are potentially hazardous. These asteroids are characterized by the fact that they could easily collide with our planet in the next few decades. Scientists also note that we should not worry if an asteroid is on a collision course set for the next 30 or 40 years, as we will be able to react to it thanks to new technology. There are many possibilities for avoiding a collision, including blowing up the asteroid or diverting it in its path.

How Far Is The Nearest Asteroid?

Because asteroids are constantly orbiting at a different speed than the Earth, there are actually multiple asteroids that are most near to us. The last time we measured was January 6, 2019. Scientists found that there are about 19,363 asteroids that are near Earth, though only around 2,000 of them are classified as “potentially hazardous”. 

These asteroids have fairly limited lifetimes compared to the lifetime of our solar system, as they are usually eliminated in just a few million years through collisions or solar system ejection.

Latest In Asteroid News

In the latest asteroid news, scientists have found a potentially hazardous asteroid that is the size of the Empire State Building. On August 10, 2019, the asteroid will come incredibly close to the Earth, though NASA says that we shouldn’t worry, as it should pass by without an incident. It is classified as a “near-Earth” asteroid, meaning it is within 30 million miles of our planet’s orbit. This particular asteroid is set to fly by about 4.5 million miles from our planet with a whopping speed of 10,400 mph.

In other news, scientists say that asteroid mining could be a new ticket for wealth. With precious and rare Earth metals such as gold, nickel, platinum, cobalt, and more, asteroids are a bit like planetary treasure chests. While we’ve seen it in science fiction for decades now, it is finally becoming a possibility. There are now a few major companies out there that are messing with the idea of starting asteroid mining programs. The major question is,

Should we even be doing this? 

Conclusion

Asteroids have given us life and they will likely be the things that destroy when they eventually come pummeling through Earth. It is up to us to respect them and learn about them so that we can attempt to avoid the unavoidable. 

What Is A Quasar?

There is no doubt that we’ve discovered a wide variety of unusual entities in our cosmos. With hundreds of years of watching the stars and trying to understand the known universe, these unusual entities end up going unexplained for long periods. One of the best examples of a long-unexplained entity is the Quasar.

Quasars are the brightest objects in the known universe. Scientists believe that these large entities are powered by supermassive black holes that are at the core of galaxies. Black holes, as most of you know, do not release any visible light. Instead, this light that we see from quasars is actually from the mass of stars and gas that surround it. This mass is known as an accretion disk. As the gas in this disk collapses into the black hole, electromagnetic radiation is released. This electromagnetic radiation can be observed by humans. 

The term “quasar” comes from a combination of ‘Quasi’ and ‘stellar’, a term which was coined by Hong-Yee Chiu, a Chinese astrophysicist. The reason for the name is because the nature of quasars are unknown.  The strongest quasars in the universities are thousands of times brighter than the Milky Way.

When Was the Quasar Discovered?

Quasars were discovered in 1963 by a man named Maarten Schmidt. It was the last piece in  the puzzle to support the theory of the Big Bang. Maarten was working as an astronomer at Mt. Palomar Observatory at the time, when he discovered the furthest object that had ever been observed from that time. This object was originally thought to be a star, as it was so incredibly bright. The problem was, it was billions of light years away and the Doppler Shift lines that identifies stars did not emit the anticipated wavelengths. 

The entity that he was studying was known as 3C 273. Upon much observation, he realized that the strange Doppler Shift lines were actually hydrogen gas lines. It was then that he knew he had discovered something completely new. This discovery helped us to realize that the universe was at least ten times bigger than we had originally thought. 

Biggest Quasar Known to Man

Scientists have long known that quasars are some of the largest objects in space. Many of them can stretch hundreds of million of light years wide. This is why it is pretty awesome to consider the fact that a group of scientists were blown when they found a mass of 73 separate quasars about 9 billion light years from our planet.

This massive structure is known as the LQG (Large Quasar GRoup). So far, it has completely undermined a prominent cosmological principle, which is the fact that the universe should be constant when it is analyzed at a massive scale.

Quasar Fun Facts

DRAGN (Double Radio Source Active Galactic Nucleus) is a mind-blowing phenomenon that stems from quasar jets, which shoot deep into space. The jets that shoot out of a quasar explode into a web of hot gas, otherwise known as an intergalactic medium, or the space between two galaxies. These DRAGNs can reach 1.5 million light years from one end to the next, far larger than the galaxy where the quasar was first produced.

Quasars are only detectable using radio telescopes, as they only appear to be bright stars on a standard optical telescope. Even the main differences between quasars and regular stars are very difficult to identify with great telescopes like the Hubble. While a normal star may be around one-hundred light years away, it is crazy to think that it looks similar to a telescope compared to a quasar that is billions of light years away.

How Far Is The Nearest Quasar?

The closest-known quasar to Earth was recently discovered in 2015 by the Hubble telescope. This quasar, known as Markarian 231, which was originally discovered back in 1969 because of its strong UV radiation properties, has just recently been “rediscovered”. Scientists now know that it is powered by what is known as a “double black hole”, two black holes that are spinning around each other.

Not only is this finding cool, as it is now the closest-known quasar, but it also suggests that two supermassive black holes may fall into each other’s orbit, creating a merger between multiple galaxies. The monumental amount of energy between two black holes shines incredibly bright, brighter than billions of stars that populate the galaxy. 

Latest Quasar News

New evidence is suggesting that quasars have the ability to support formations of stars when they form. Researchers using the European Space Agency’s XMM Newton Telescope stumbled upon a strange blip in a quasar. They theorized that it must be a star formation. Scientists are now classifying these quasars as “cold quasars”, which are essentially galaxies with quasars at the center that have an abundance of cold gas and the ability to produce stars. These cold quasars could give some insight into how our universe will eventually end.

A mysterious disk of material was recently found in space. The crazy part is, the astronomy community says it should not be there. This disk, which is inside NGC 3147, is spinning around a large supermassive black hole about 130 million light years from us. The even stranger part is that the disk looks like it should have a quasar in the center providing a beacon of light, though the quasar is not there. The center of the black hole is also dead silent, which is strange considering the fact that we are usually able to pick up radio waves.

Conclusion

With beauty and mystery, quasars help us to explain the vast expansion that our universe is going through. Their light continues to shine bright, acting as beacons for us to explore further than ever before.

What Is A Nebula?

See that giant cloud of dust and gas that is spread across the night sky? That is a nebula. The world nebula comes from the Spanish word for “cloud”. For many years, these massive formations have intrigued scientists by providing them with light years of exploration.

Nebulae come from dying stars, such as supernovas, that explode, releasing gas and dust. There are other nebulae out there that are known as “star nurseries”, as these are the regions where brand new stars are coming into formation.

Nebulae are made up of mostly helium and hydrogen. The dust and gas spreads out across millions and millions of miles, though as gravity begins to pull the matter together, the clumps become much larger and stronger. These dust and gas clumps will eventually become so large that it will collapse on itself, forming its own field of gravity. This massive collapse helps to heat up the core of the nebula, which eventually turns into a star. 

Currently, there are four major classes of Nebulae:

  • Diffuse Nebulae – These do not have defined boundaries. They are divided into two sub-groups: Emission Nebulae and Reflection Nebulae. Emission Nebulae are known as HII regions, as they are made mostly of ionized hydrogen. Reflection Nebulae are known to release incredible amounts of light, which reflects off the stars nearby.
  • Dark Nebulae – These are opaque clouds without radiation that is visible. Thanks to the large amount of dust, these are excellent infrared emissions sources.
  • Supernova Remnant Nebulae – These are formed after supernova explosions. These explosions leave behind a cloud of gas and dust to create the Nebula formation.
  • Planetary Nebulae – These are formed at the end stages (Red Giant Phase) of dying stars. The stars lose enough material that the emitted UV radiation ionizes any of the surrounding dust material.

How Were Nebulae Discovered?

During the Middle Ages, many astronomers noted the presence of nebulous objects throughout the night sky. In 150 CE, Ptolemy wrote about the nebulous Almagest stars in his book. Here he discussed the luminous regions that appeared between Leo and Ursa Major. In 964 CE, Abd-al-Rahman al-Sufi, a Persian Astronomer of the time, noted a small cloud in the Andromeda Galaxy. 

As telescopes improved over time, the first nebula observations were made. In 1610, Nicolas-Claude Fabri de Peiresc, a French astronomer of the time, recorded the very first observation of a nebula known as the Orion Nebula. It wasn’t up until 1659 that the first study of the Orion Nebula was performed by Dutch physicist Christiaan Huygens.

Largest Nebula Known To Man

The largest Nebula in the universe is known as the Tarantula Nebula. This massive star factory is about 1000 light-years in length. It was first discovered by Nicolas-Louis de Lacaille during a Cape of Good exploration. It is extremely luminous with an estimated mass cluster of around 400,000 solar masses. Scientists believe that it will eventually become a globular cluster.

This particular nebula is the most active of the starburst regions in the local galaxy group. Before it was classified as a Nebula in 1751, it was thought to be a massive Magellanic Cloud.

Nebula Fun Facts

Contrary to what you might think from looking at photographs, Nebulae are constantly in motion. The nebulous clouds mix and churn all the time, creating magnetic fields.

As you now know, stars are formed within Nebulae. According to astronomers, the gas and dust that are present within nebulae will compress together with the power of their own gravitational force. As the clouds contract and compress, the entirety of a nebula becomes much denser. As the nebula becomes more dense, it also becomes much hotter. When the nebula reaches maximum heat, the hydrogen inside will ignite, creating new stars.

Planetary Nebulae have what we know as “bipolar structures”. Essentially, the look like hourglasses with almost symmetrical triangles spreading out in each direction from the center. Many people say that they look just like butterflies. 

There is a nebula out there called the Horsehead Nebula, which you guessed it, resembles the head of a horse. It is a dark nebula that is incredibly fascinating. It took form thanks to the light that surrounded it. The dark clouds that form around it helps to create the shape, similar to how a shadow is created.

How Far Is The Nearest Nebula?

The Helix Nebula is the closest planetary nebula to Earth and can be found in the constellation Aquarius. It was discovered in the early 19th century by a man named Karl Ludwig Harding. The distance is around 694.7 light years from Earth. Many refer to this Nebula as the “Eye of Sauron”, referencing a pop culture entity from Lord of the Rings.

Latest Nebula News

In recent news, the Crab Nebula has just hit Earth with some of the highest-recorded astrophysical gamma rays of all time. Astronomers detected this blast from a unique observatory in the Tibet mountains. It is known as the Tibet Air Shower Array, as it is composed of an array of underground pools that can detect cosmic particles with high energy. The nebula hit Earth with over 100 trillion electronvolts. To put that into perspective, a mosquito has about 1 electronvolt of energy. The Hubble Telescope has just recently captured a firework-like explosion of a cosmic nebula eruption that has been happening for almost 200 years. This petulant nebula known as Eta Carinae, is now exploding with red, white, and blue gases in a somewhat dramatic and patriotic display. This ‘great eruption’ first began in the 1840s.

What are Galaxies?

You’ve probably heard of the Milky Way. If you haven’t, you should know that you live inside of it! Our galaxy was formed billions of years ago and has hundreds of billions of stars that are held together by an immense force known as gravity. Galaxies in general are massive collections of dust, gas, and stars that are held together with the force of gravity

Scientists believe that galaxies were formed after the Big Bang. They say that the universe was once composed of small, subatomic particles and radiation. It is speculated that particles and radiation slowly formed together to create clusters of stars, which would eventually create galaxies. It is also speculated that they formed into giant masses of matter, which would later divide up into smaller galaxies.

Galaxies come in different forms. Some are similar to ours with a large, spiral shape, and they are known as “spiral galaxies”. Those galaxies resemble pinwheels. Other galaxies look like blobs and have shapes that are irregular. These galaxies are known as elliptical galaxies.

When Were Galaxies Discovered?

The idea of the galaxy was proposed by a man named Thomas Wright in 1750. It wasn’t until the early 20th century, though, that the astronomy community believed that the majority of the universe was within the Milky Way Galaxy. A man by the name of Harlow Shapley who was a scientist at the Harvard College Observatory, believe that the spiral-shaped blobs that they had seen across the universe were actually different “island universes”. 

In 1924, Edwin Hubble discovered a variety of pulsating stars, which he dubbed “Cepheid variables”. He said that these celestial objects were far beyond the boundaries of our own galaxy and were made up of unique star collections. He began measuring the distance of these galaxies from our own. When he finished, he measured their Doppler Shift to see how fast they were moving. He eventually concluded that the universe was expanding and there were many other galaxies moving at fast rates beyond ours.

Biggest Galaxy

The largest galaxy that is known to man is known as IC 1101. At just over 6 million light years in diameter, this massive galaxy is located about a billion light years away and is the biggest galaxy that we have ever observed. Its boundaries extend about 2 million light years from its core. In whole, it contains about 100 trillion stars. 

To put all of this into relativity, the Milky Way is about 100,000 light years in diameter. If this galaxy were to move its way into our realm, it would not only swallow our galaxy like a snack, but would also swallow up the Andromeda galaxy, the Triangulum galaxy, and the Magellanic Clouds, as well as all of the space in-between. 

This galaxy was formed thanks to the collisions of many galaxies over billions of years. We can now see that this galaxy is not creating tons of new stars, meaning that if it does not continue to collide with galaxies, it will eventually fade away.

Galaxy Fun Facts

At one point, the Hubble Space Telescope was directed up into a small portion of space to observe and report. In only 12 days, the telescope found about 10,000 different galaxies, each with their own unique shapes and sizes. That fact alone helps us to speculate that there could easily be hundreds of billions of galaxies in the universe.

We now know that our Galaxy will one day smash into the Andromeda galaxy, which is our closest galaxy neighbor. The act of one galaxy bumping into another happens pretty often. Most of the time, planets never even touch, as the outer rims of galaxies are spread so wide that the planets can miss each other all together. Don’t fret though, as scientists don’t expect this to happen for another 5 billion years.

Galaxies rotate incredibly fast, much faster than we can predict based on the gravity that is contained within their stars. The extra gravitational force that we can not predict is said to be from dark matter, of which no light or radiation is emitted.

How Far Is The Nearest Galaxy?

The Milky Way has about 54 neighbors within the Virgo Supercluster. The closest major galaxy in this large cluster is known as the Andromeda Galaxy. This spiral galaxy is very similar to ours, though not technically the closest. The closest galaxy is actually a dwarf galaxy known as the Canis Major Dwarf Galaxy. It lies about 25-thousand light years from the center of our solar system. 

This dwarf galaxy is said to carry around about a billion stars in total and has an elliptical shape. Behind it is a large filament of stars that shoots out like a long galactic trail. Scientists refer to this structure as the Monoceros Ring.

Latest Galaxy News

In 2018, a new image from the Hubble Telescope was able to string together about 15,000 different galaxies, which was one of the largest discoveries in galaxy history. Scientists say this will provide enough hunting ground for years of galactic study. In the same period, there were hundreds of galaxies discovered behind a massive black hole. Up until 2018, that black hole was blocking their light.

Astronomers have just recently discovered a new neighboring galaxy that is in the global cluster known as NGC 6752. This new dwarf galaxy is known as Bedin 1 and it is obscured by the globular cluster of stars. Thanks to the Hubble Telescope, this small globular star cluster, located about 13,000 light years away from the edge of the Milky Way, was discovered. Check out this video of the telescope zooming in on Bedin 1 and the surrounding cluster.

What is a Pulsars

As one of the strangest entities of the cosmos, Pulsars, otherwise known as the “lighthouses in space”, are spinning neutron stars that emit electromagnetic radiation. This radiation can only be seen with the human eye if that person is standing in the same path as it. The reason that they are referred to as “pulsars” is because of the radiation emissions that seem to be pulsating among the stars. 

Though they may look like your typical star, blinking on and off, they are actually far from it. To be exact, pulsars are artifacts of what once were enormous stars. They are formed when a massive star, sometimes eight times the size of our sun, explodes as a supernova. The outer layers are then hurled into space and the core is squeezed by gravity. 

While most will explode into black holes thanks to the sheer size, a good majority of the smaller ones don’t have that same force. Instead, they end up increasing in rotational speed, spinning hundreds of times second, emitting beams of radiation that we can see. 

When Were Pulsars Discovered?

The first radio pulsars were discovered in 1967 by an Astrophysicist from Northern Ireland by the name of Jocelyn Bell Burnell, while she was still a student at Cambridge University. She discovered the pulsars in collaboration with her advisor, Dr. Anthony Hewish.

It was in July of that year that she detected that something was off on her chart-recorder papers that were used to track stars in the sky. At first, her and Hewish had no idea what the signals were doing. She found that she was getting a pulsating signal that was pulsing with odd regularity. It was named “Little Green Man 1”  at the time to reference sci-fi extraterrestrial culture of the time. Eventually, that pulsating signal was dubbed a “rotating neutron star”.

It was long debated that she did not receive a Nobel prize for her discovery, as it was one of the largest discoveries in space history, though, in 2018, she was finally given the biggest recognition for her great space achievement when she was awarded the Special Breakthrough Prize In Fundamental Physics

PSR J0348+0432 – The Big Kahuna

Just within this past decade, astronomers stumbled upon one of the largest objects in space that we have found to date. They discovered PSR J0348+4032 using ESO’s Very Large Telescope. This specific pulsar is two times as heavy as the sun, though it is only 20 km in diameter. Neutron stars are known to be incredibly dense, though the amount of matter that is packed into this relatively small space was very surprising.

This star spins at 25 times per second, emitting a large beam of electromagnetic radiation. What is even stranger is that it has a companion star known as a “white dwarf”. The combined gravity of the stars creates visible ripples in space, which is why the star was so easily discoverable.

Fun Facts

Pulsars have the most energy when they first form. They begin with high rotational speeds, releasing electromagnetic power over millions of years. They will continue to slow down after about 10 million years (though they can last for almost 100 million) before eventually going silent.

Because pulsars spin with mysterious regularity, astronomers use them as natural atomic clocks. They are so accurate in terms of time keeping that astronomers actual compare them to standard, mechanical timers.

Astronomers believe that the collection of  pulsars create the most accurate map of the galaxy. If you look at the NASA Voyager craft, you’ll find a map with 14 different pulsars in our region around the sun. Essentially, if there were extraterrestrials out there who wanted to find Earth, pulsars create the most accurate map out there.

If you know anything about the band Joy Division, you probably know about their most popular album cover from Unknown Pleasures, which was released in 1979. The picture on the album cover originates from the work of Harold Craft, a postgraduate student who did a thesis on Jocelyn Bell Burnell in 1970. Those mysterious wiggly lines are actually a graphical recording of a pulsar known as B1919+21.

Nearest Pulsar

The closest pulsar to Earth is the PSR J0108-1431. It is right in the path of the Cetus constellation, which is about 280 light years from Earth. This pulsar was discovered in 1993 by Thomas Tauris, a Danish astronomer, using the Parkes 64-meter radio telescope. It took so long because the luminosity is unusually low.

This particular pulsar is weak in relativity, 1000 times weaker than your typical radio pulsar. Astronomers believe that PSR J0108-1431 is just the tip of a huge group of dim pulsars that are spread around the Milky Way Galaxy. 

Latest Pulsar News

China’s five-hundred-meter telescope has now discovered 86 pulsars since it began operating in 2016. This telescope, known as FAST, has achieved in-motion scanning abilities that have helped it to exceed prior expectations. According to Li Di, the chief scientist of the FAST Project, the telescope has actually just detected one of the faintest and fastest pulsars that has ever been seen. 

Scientists have just recently discovered a pulsar (PSR B1957+20) with a brown dwarf companion. This particular pulsar is known as a “Black Widow”, as it emits powerful radiation blasts that consumer companion stars. As the Black Widow continues to consume the brown dwarf star, scientists have noticed that it has started to create an SOS signal, and a very musical one at that. Listen closely and you can hear the Brown Dwarf as it sings a steady Eb note with small percussive elements in-between.

What is a Falling Star?

Poets talk about falling stars; astronomers talk about meteors. They’re the same thing, but the phenomenon resonates differently for scientists and regular people. For many of us, pretty much the most exciting thing about watching the night sky is catching sight of a falling or shooting star.

But What Is It Really?

A falling or shooting star is the visible path of a meteoroid (or debris from combusting meteoroids of any size) entering the Earth’s atmosphere. Upon entry it is referred to as a meteor; if it hits the Earth intact it is referred to as a meteorite. The bright light that even dust-sized falling stars emit as they heat up and disintegrate during their journey through the atmosphere can make them appear to be much larger than they are. If an actual star were ever to fall to earth, the planet would be instantly obliterated. Real stars (such as Earth’s sun) are enormous.

On a normal night, depending on location and the level of light pollution, most stargazers can expect to see a falling or shooting star every 20 minutes or so. They appear abruptly and arc briefly across the dome of the night sky. During a meteor shower, when meteors, debris and dust move in a cluster, the sky can seem full of falling or shooting stars.

A Brief History

People have always been excited, and often scared, by this celestial phenomenon. Ancient Greek philosophers such as Aristotle posited theories (incorrectly as it turned out) about what caused stars to fall and blaze so brightly, and historians and writers the world over have tracked and described these events — long before astronomy was even considered a science.

Arab historical accounts refer to the year of 902 AD as the Year of the Stars. At this time the Leonid meteors (the Leonids are a spectacular meteor shower event that occurs every 30 years or so) were especially active over Northern Africa and the Mediterranean.

In 1833, another Leonids event occurred over much of eastern North America, sparking renewed interest, both public and scientific, in falling stars and meteor showers. American astronomer Denison Olmstead correctly noted that the falling stars seemed to originate from the same part of the sky (which he called the radiant) and that gravity played a part in their fall. His work, which included many first hand accounts from non-scientists, ushered in a new era of observation and scientific research.

How to See Falling Stars Clearly

Some shooting stars can be seen as part of a seasonal phenomenon. The Perseid meteor shower, for example, derives from the debris stream of the periodic comet Swift-Tuttle, which takes 133 years to orbit the Earth. The Perseids appear in the skies across the Northern Hemisphere late each summer, and have since the mid-1800s. At the peak of this annual event, up to 60 falling stars can be seen between midnight and dawn, depending on light conditions. Generally, the less ambient light from homes or structures, or the moon, the better the chances of spotting a falling star. Some countries are establishing Dark Sky Preserves, to help amateur astronomers get the best possible falling star experience.

Whether we call them stars or simple comet debris, falling or shooting, the phenomenon triggers a special visual experience for children and adults around the world. So much so that a sweet ritual usually accompanies the sighting of a falling star. While in ancient Greece shooting or falling stars were believed to mark the passage of souls, in many modern societies the tradition is to make a wish when you see one.

What is Comet?

Hidden in the outer reaches of our solar system are chunks of frozen gas, rocks and dust — the nuclei of comets. As these unassuming, icy lumps travel toward the sun, they’re transformed into brilliant celestial objects.

In ancient civilizations, the unexpected presence of these glowing objects in the heavens inspired fear, but we now know that comets are billions of years old and an intricate part of our solar system.

How Comets are Formed

Comets were created when the solar nebula collapsed to form the sun and planets. The debris froze together in clumps in distant regions of the solar system, creating a comet’s nucleus.

As a comet orbits near the sun, the ice heats and vaporizes, generating a thin atmosphere around the nucleus called a coma. Loose bits of rock and dust are blown by solar winds to form two tails illuminated by the sun. One tail contains dust particles and shines yellow and white. The second tail consists of ionized molecules and glows blue.

Where Do Comets Come From?

There are two types of comets. Short-period comets have an orbit of less than 200 years and are believed to travel from the Kuiper Belt outside of Neptune’s orbit. Long-period comets take more than 200 years for a return visit and originate in the Oort cloud, the most distant part of our solar system.

Comets have been cited as early as 1000 BC and were named kometes by Greek philosophers, which means a head of long hair. Individual comets are generally named for the persons who discovered them.

Notable Comets in Recent History

These recent comets generated scientific and public interest:

  • Halley: Astronomer Edmond Halley proposed that a comet appearing in 1531, 1607 and 1682 was the same comet with a 75-year orbit. He accurately predicted its return in 1758. Halley’s Comet appeared in 1986 and will return in 2061.
  • Iyeka-Seki: The brightest comet of the 20th century, Iyeka-Seki is a Kreutz Sungrazer — a comet whose orbit takes it close to the sun. In 1965, Iyeka-Seki approached to within 744,000 miles of the sun’s center. It’s next expected in 3000.
  • Hyakutake: In 1996, a spacecraft called Ulysses unexpectedly crossed the tail of long-period comet Hyakutake. Scientists realized the accidental interaction was due to the surprising length of the comet’s tail. Approximately 350 million miles long, it was twice the length of any other known comet. Hyakutake is not expected for another 14,000 years.
  • Hale-Bopp: In 1997, Hale-Bopp became the most widely-viewed comet, visible to the naked eye for 18 months. Its nucleus measured 60 miles, compared to an average nucleus which ranges from 300 feet to 30 miles. Hale-Bopp released dust streams more than eight times that of previously observed comets. Its next approach is in 4385.
  • McNaught: After McNaught appeared in 2007, scientists examined the space disturbed by its presence and realized the comet’s scale. Ulysses took 2.5 days to cross the shocked solar winds around Hyakutake, but it took 18 days for it to cross those of McNaught.

Future Observations

There have been a dozen international space missions studying short-period comets. The European Space Agency is planning a future three-spacecraft mission to visit a long-period comet as it enters our inner solar system.

Astronomer Alan Hale, co-discoverer of Hale-Bopp, regularly documents comets. He shares information about observable comets and incoming ones.

Comets have been roaming our solar system for billions of years. Whether they’re quietly travelling distant regions or making a spectacular splash in our sky, they’re a beautiful reminder of the vastness of our galaxy and our ancient origins.

Cataclysmic Variables

The majority of stars are not solo stars like our Sun. Instead, they are binary or trinary systems, and in some cases, there can be many more. The stars don’t have to be equal, either. You might get a small dwarf star circulating a red giant, or perhaps a main-sequence star gradually being ripped apart by a black hole. Or they could be equal. But cataclysmic variable stars are essentially stars that go boom on a regular basis. What’s up with that?

The Discovery of Cataclysmic Variable Stars

Cataclysmic variable stars have long been observed, with the first known observation by Pére Dom Anthelme in 1670. Others carried on that work, particularly during the 19th century with bigger and better telescopes. More importantly, spectroscopy became useful to identify anomalies, such as those often found with novae. These stars were oddities that periodically brightened and dimmed, and spectroscopic measurements also varied.

During the 1940s, spectroscopic data showed that there were two distinct sets of emission spectra, which suggest that a known dwarf nova was actually two stars: a binary system. Further data backed this up.

In the 1960s, a series of missile launches were used to scan the heavens. Essentially, it was an X-ray detector strapped to an ICBM. The launches were programmed to scan a particular sector for 3 to 5 minutes, and then they would fall back to Earth with the data. One launch detected an X-ray transient, which is an X-ray burst that momentarily appeared and then disappeared when it was next scanned.

This provided the first inkling that the universe was even more violent than we had thought.

This system was replaced by the Vela series of satellites, and they detected even more X-ray bursts, as well as more than a few from their official job: nuclear weapon test detection. Other satellites supplanted them.

All of this data came in handy when eventually declassified. Scientists in the ’70s started to work out what these X-ray bursts were.

Stars That Go Boom

The answer is surprisingly simple. Take one main-sequence (usually dwarf) star, and then pair it with a white dwarf. Because the stars are orbiting very closely, they are very hard to tell apart. The main sequence star must also pass near or through the dwarf star’s accretion disc. This strips out a load of the main sequence star’s fusible material, which immediately reacts violently on the surface of the white dwarf. The result is a series of huge and controlled thermonuclear explosions that are many orders of magnitude bigger than the largest thermonuclear weapon humanity has ever created.

It’s this that creates a huge burst of X-rays and gamma rays. This has the effect of sterilizing all life in the system and perhaps further.

There are several types of CV system:

  • Novae are extremely bright. This creates a new, incredibly bright light in the sky that can last for several months. These include M31N 2008-12a.
  • Dwarf nova is not as bright, and their output can perhaps last a few hours or as long as a couple of weeks. These are the most common type of CV. These include U Geminorum and SS Cygni.
  • Polars are magnetic cataclysmic variables. They have strong magnetic fields that force the material to go to the north and south poles, where they continuously burn. They glow, but they do not produce outbursts. Polars include AM Herculis.

Binary systems are some of the most common in the Milky Way, and it’s almost inevitable that a good portion of them are some sort of cataclysmic variable star or will be. Despite the lack of mainstream news interest, understanding them is important if we are to understand our place in the galaxy.