I don’t know about you, but I’d like to live forever. In a few decades, the Singularity will happen, and I’ll merge with the artificial super intelligence, transcend this meat-based existence and then explore the Hubble Sphere with the disembodied voice of Scarlett Johansson as my guide. See you on the other side, suckers.
Not Elon Musk, though. He thinks we should fear our benevolent computer overlords, and make our way to Mars, where we can live out the rest of our days growing potatoes, huddling in lava tubes, and fighting a guerilla war against a spiritually enlightened and lovable artificial lifeform that really only has our best interests at heart.
In case you have no idea who I’m talking about, Elon Musk is the CEO of the revolutionary rocket company SpaceX, as well as the Tesla electric car company.
Elon Musk. Credit: SpaceX
It might sound crazy, but the whole reason Elon Musk started SpaceX was that he wanted to help humanity explore the Solar System. But in order to do that, he’d need inexpensive rocket launches. And since those didn’t exist yet, he started a rocket company to provide launches at a fraction of the cost of the existing launch providers.
At the time I’m recording this video, SpaceX has already had many successful launches. They’ve successfully landed rockets back at their landing pad, and on a floating barge in the Atlantic Ocean. It really looks like Elon Musk’s plans are going to work, and we’re going to become a true spacefaring civilization.
Elon Musk recently revealed the design for what he calls the Interplanetary Transport System (ITS) – an upgraded version of his Mars Colonial Transporter (MCT). This ship, according to Musk, will ferry 100 passengers to Mars every 26 months (when the planets are closest), and says that tickets will cost $500,000 per person (at least initially).
Wow, 2024, huh? That’s pretty soon! I’m not sure if you realize how complicated and dangerous this mission will be. This guy is really serious.
An artist’s illustration of the Falcon Heavy rocket. Image: SpaceX
The plan involves using a scaled up version of SpaceX’s Falcon rocket, known as the Falcon Heavy, to test techniques for orbiting, descent, and landing on Mars. By bolting 3 Falcon boosters together, this new launch vehicle will be capable of blasting 54,000 kilograms into orbit, or 22,000 kilograms to geostationary orbit, or 13,900 kilograms to Mars.
It’ll even send 2,600 kilograms to Pluto, if that’s what you’re looking for. So far a Falcon Heavy hasn’t been tested yet, but they’re due to start flying by early 2017.
The spacecraft payload is known as the Red Dragon, an uncrewed version of the Dragon 2 which Musk plans to send to Mars in 2018. This is a specially modified version of the SpaceX Dragon capsule which has already successfully delivered cargo to the International Space Station.
Red Dragon will weigh 10 times more than NASA’s Curiosity Rover, and this is a big problem. Landing this much spacecraft on the surface on Mars is incredibly challenging. The atmosphere is just 1% the thickness of Earth’s, so it doesn’t provide any way to slow a spacecraft down from its interplanetary flight.
In the past, rocket engineers have had to develop these complicated landing systems with parachutes, airbags, and retrorockets. But there’s limit to how heavy a mass you can land this way. Curiosity pretty much tested that limit.
Artists concept for sending SpaceX Red Dragon spacecraft to land propulsively on Mars as early as 2018. Credit: SpaceX
Red Dragon makes it simple. It’ll be equipped with 8 SuperDraco engines built into the capsule which will fire once it enters the atmosphere, and allow it to touch down gently on the surface of Mars. If this works, there’ll be no limit to the size of payloads SpaceX can deploy to the surface of Mars. In fact, once it gets Mars right, Red Dragon should be able to land softly on pretty much any object in the Solar System.
Elon Musk does seem serious about setting up a colony on Mars. Once this first Red Dragon land on the surface, they’ll send capsule after capsule during the perfect Mars launch window that opens up every 2 years or so.
Over time, a real colony’s worth of supplies will be gathered on the surface of Mars. SpaceX will have worked out all the tricks to safely sending spacecraft to the Red Planet, and it’ll be time to send actual colonists willing to live out the rest of their lives on Mars.
We’re still not entirely sure humans can survive long term on Mars. The lack of atmosphere will suffocate you, the unfiltered radiation will fill you with cancer, and the low gravity may melt your bones. Seriously, humanity has never tried living in such an extreme environment.
Musk is so serious about this plan to send humans to Mars, that he’s stated that he’ll never take SpaceX public. The company will remain private so that it’ll prioritize the goal of colonizing Mars over any kind of short sighted shareholder cash grab.
If everything goes well, the first Red Dragon will launch for Mars in 2018. And then more will go every 2 years after that. And at some point, humans will climb into a Red Dragon capsule and blast off to begin the first human colony on Mars.
So when can we die on Mars? Musk hasn’t given us a firm date yet, but if that first Red Dragon does launch in 2018, we won’t have to wait too much longer.
This article was originally published in 2008, but has been updated several times now to keep track with our advancing knowledge of the cosmos!
My six-year old daughter is a question-asking machine. We were driving home from school a couple of days ago, and she was grilling me about the nature of the Universe. One of her zingers was, “What’s the Biggest Star in the Universe”? I had an easy answer. “The Universe is a big place,” I said, “and there’s no way we can possibly know what the biggest star is”. But that’s not a real answer.
So she refined the question. “What’s the biggest star that we know of?” Of course, I was stuck in the car, and without access to the Internet. But once I got back home, and was able to do some research, I learned the answer and thought I’d share it with the rest of you But to answer it fully, some basic background information needs to be covered first. Ready?
Solar Radius and Mass:
When talking about the size of stars, it’s important to first take a look at our own Sun for a sense of scale. Our familiar star is a mighty 1.4 million km across (870,000 miles). That’s such a huge number that it’s hard to get a sense of scale. Speaking of which, the Sun also accounts for 99.9% of all the matter in our Solar System. In fact, you could fit one million planet Earths inside the Sun.
Using these values, astronomers have created the terms “solar radius” and “solar mass”, which they use to compare stars of greater or smaller size and mass to our own. A solar radius is 690,000 km (432,000 miles) and 1 solar mass is 2 x 1030 kilograms (4.3 x 1030 pounds). That’s 2 nonillion kilograms, or 2,000,000,000,000,000,000,000,000,000,000 kg.
Artist’s depiction of the Morgan-Keenan spectral diagram, showing the difference between main sequence stars. Credit: Wikipedia Commons
Another thing worth considering is the fact that our Sun is pretty small, as stars go. As a G-type main-sequence star (specifically, a G2V star), which is commonly known as a yellow dwarf, its on the smaller end of the size chart (see above). While it is certainly larger than the most common type of star – M-type, or Red Dwarfs – it is itself dwarfed (no pun!) by the likes of blue giants and other spectral classes.
Classification:
To break it all down, stars are grouped based on their essential characteristics, which can be their spectral class (i.e. color), temperature, size, and brightness. The most common method of classification is known as the Morgan–Keenan (MK) system, which classifies stars based on temperature using the letters O, B, A, F, G, K, and M, – O being the hottest and M the coolest. Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest (e.g. O1 to M9 are the hottest to coldest stars).
In the MK system, a luminosity class is added using Roman numerals. These are based on the width of certain absorption lines in the star’s spectrum (which vary with the density of the atmosphere), thus distinguishing giant stars from dwarfs. Luminosity classes 0 and I apply to hyper- or supergiants; classes II, III and IV apply to bright, regular giants, and subgiants, respectively; class V is for main-sequence stars; and class VI and VII apply to subdwarfs and dwarf stars.
The Hertzspirg-Russel diagram, showing the relation between star’s color, AM. luminosity, and temperature. Credit: astronomy.starrynight.com
There is also the Hertzsprung-Russell diagram, which relates stellar classification to absolute magnitude (i.e. intrinsic brightness), luminosity, and surface temperature. The same classification for spectral types are used, ranging from blue and white at one end to red at the other, which is then combined with the stars Absolute Visual Magnitude (expressed as Mv) to place them on a 2-dimensional chart (see above).
On average, stars in the O-range are hotter than other classes, reaching effective temperatures of up to 30,000 K. At the same time, they are also larger and more massive, reaching sizes of over 6 and a half solar radii and up to 16 solar masses. At the lower end, K and M type stars (orange and red dwarfs) tend to be cooler (ranging from 2400 to 5700 K), measuring 0.7 to 0.96 times that of our Sun, and being anywhere from 0.08 to 0.8 as massive.
Based on the full of classification of our Sun (G2V), we can therefore say that it a main-sequence star with a temperature around 5,800K. Now consider another famous star system in our galaxy – Eta Carinae, a system containing at least two stars located around 7500 light-years away in the direction of the constellation Carina. The primary of this system is estimated to be 250 times the size of our Sun, a minimum of 120 solar masses, and a million times as bright – making it one of the biggest and brightest stars ever observed.
Eta Carinae, one of the most massive stars known, located in the Carina constellation. Credit: NASA
There is some controversy over this world’s size though. Most stars blow with a solar wind, losing mass over time. But Eta Carinae is so large that it casts off 500 times the mass of the Earth every year. With so much mass lost, it’s very difficult for astronomers to accurately measure where the star ends, and its stellar wind begins. Also, it is believed that Eta Carinae will explode in the not-too-distant future, and it will be the most spectacular supernovae humans have ever seen.
In terms of sheer mass, the top spot goes to R136a1, a star located in the Large Magellanic Cloud, some 163,000 light-years away. It is believed that this star may contain as much as 315 times the mass of the Sun, which presents a conundrum to astronomers since it was believed that the largest stars could only contain 150 solar masses. The answer to this is that R136a1 was probably formed when several massive stars merged together. Needless to say, R136a1 is set to detonate as a hypernova, any day now.
In terms of large stars, Betelgeuse serves as a good (and popular) example. Located in the shoulder of Orion, this familiar red supergiant has a radius of 950-1200 times the size of the Sun, and would engulf the orbit of Jupiter if placed in our Solar System. In fact, whenever we want to put our Sun’s size into perspective, we often use Betelgeuse to do it (see below)!
Yet, even after we use this hulking Red Giant to put us in our place, we are still just scratching the surface in the game of “who’s the biggest star”. Consider WOH G64, a red supergiant star located in the Large Magellanic Cloud, approximately 168,000 light years from Earth. At 1.540 solar radii in diameter, this star is currently one of the largest in the known universe.
But there’s also RW Cephei, an orange hypergiant star in the constellation Cepheus, located 3,500 light years from Earth and measuring 1,535 solar radii in diameter. Westerlund 1-26 is also pretty huge, a red supergiant (or hypergiant) located within the Westerlund 1 super star cluster 11,500 light-years away that measures 1,530 solar radii in diameter. Meanwhile, V354 Cephei and VX Sagittarii are tied when it comes to size, with both measuring an estimated 1,520 solar radii in diameter.
The Largest Star: UY Scuti
As it stands, the title of the largest star in the Universe (that we know of) comes down to two contenders. For example, UY Scuti is currently at the top of the list. Located 9.500 light years away in the constellation Scutum, this bright red supergiant and pulsating variable star has an estimated average median radius of 1,708 solar radii – or 2.4 billion km (1.5 billion mi; 15.9 AU), thus giving it a volume 5 billion times that of the Sun.
However, this average estimate includes a margin of error of ± 192 solar radii, which means that it could be as large as 1900 solar radii or as small as 1516. This lower estimate places it beneath stars like as V354 Cephei and VX Sagittarii. Meanwhile, the second star on the list of the largest possible stars is NML Cygni, a semiregular variable red hypergiant located in the Cygnus constellation some 5,300 light-years from Earth.
A zoomed-in picture of the red giant star UY Scuti. Credit: Rutherford Observatory/Haktarfone
Due to the location of this star within a circumstellar nebula, it is heavily obscured by dust extinction. As a result, astronomers estimate that its size could be anywhere from 1,642 to 2,775 solar radii, which means it could either be the largest star in the known Universe (with a margin of 1000 solar radii) or indeed the second largest, ranking not far behind UY Scuti.
And up until a few years ago, the title of biggest star went to VY Canis Majoris; a red hypergiant star in the Canis Major constellation, located about 5,000 light-years from Earth. Back in 2006, professor Roberta Humphrey of the University of Minnesota calculated its upper size and estimated that it could be more than 1,540 times the size of the Sun. Its average estimated mass, however, is 1420, placing it in the no. 8 spot behind V354 Cephei and VX Sagittarii.
These are the biggest star that we know of, but the Milky way probably has dozens of stars that are even larger, obscured by gas and dust so we can’t see them. But even if we cannot find these stars, it is possible to theorize about their likely size and mass. So just how big can stars get? Once again, Professor Roberta Humphreys of the University of Minnesota provided the answer.
Size comparison between the Sun and VY Canis Majoris, which once held the title of the largest known star in the Universe. Credit: Wikipedia Commons/Oona Räisänen
As she explained when contacted, the largest stars in the Universe are the coolest. So even though Eta Carinae is the most luminous star we know of, it’s extremely hot – 25,000 Kelvin – and therefore only 250 solar radii big. The largest stars, in contrast, will be cool supergiants. Case in point, VY Canis Majoris is only 3,500 Kelvin, and a really big star would be even cooler.
At 3,000 Kelvin, Humphreys estimates that cool supergiant would be as big as 2,600 times the size of the Sun. This is below the upper estimates for NML Cygni, but above the average estimates for both it and UY Scutii. Hence, this is the upper limit of a star (at least theoretically and based on all the information we have to date).
But as we continue to peer into the Universe with all of our instruments, and explore it up close through robotic spacecraft and crewed missions, we are sure to find new and exciting things that will confound us further!
And be sure to check out this great animation that shows the size of various objects in space, starting with our Solar System’s tiny planets and finally getting to UY Scuti. Enjoy!
Planets and other objects in our Solar System. Credit: NASA.
When we look at beautiful images of the planets of our Solar System, it is important to note that we are looking at is not always accurate. Especially where their appearances are concerned, these representations can sometimes be altered or enhanced. This is a common practice, where filters or color enhancement is employed in order to make sure that the planets and their features are clear and discernible.
So what exactly do the planets of the Solar System look like when we take all the added tricks away? If we were to take pictures of them from space, minus the color enhancement, image touch-ups, and other methods designed to bring out their details, what would their true colors and appearances be? We already know that Earth resembles something of a blue marble, but what about the other ones?
In a previous episode, I said that traveling within the Solar System is hard enough, traveling to another star system in our lifetime is downright impossible. Many of you said it was the most depressing episode I’ve ever done .
The distance to Pluto is, on average, about 40 astronomical units. That’s 40 times the distance from the Sun to the Earth. And New Horizons, the fastest spacecraft traveling in the Solar System took about 10 years to make the journey.
The distance to Alpha Centauri is about 277,000 astronomical units away (or 4.4 light-years). That’s about 7,000 times further than Pluto. New Horizons could make the journey, if you were willing to wait about 70,000 years. That’s about twice as long as you’d be willing to wait for Half Life 3.
But my video clearly made an impact on a plucky team of rocket scientists, entrepreneurs and physicists, who have no room in their personal dictionary for the word “impossible”. Challenge accepted, they said to themselves.
In early April, 2016, just 8 months after I said it was probably never going to happen, the billionaire Yuri Milner and famed physicist Stephen Hawking announced a strategy to send a spacecraft to another star within our lifetime. In your face Fraser, they said… in your face.
Project Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be humanity’s first interstellar voyage. Credit: breakthroughinitiatives.org
The project will be called Breakthrough Starshot, and it’s led by Pete Worden, the former director of NASA’s AMES Research Center – the people working on a warp drive.
The team announced that they’re spending $100 million to investigate the technology it’ll take to send a spacecraft to Alpha Centauri, making the trip in just 20 years. And by doing so, they might just revolutionize the way spacecraft travel around our own Solar System.
So, what’s the plan? According to their announcement, the team is planning to create teeny tiny lightsail spacecraft, and accelerate them to 20% the speed of light using lasers. Yes, everything’s made better with lasers .
We’ve talked about solar sails in the past, but the gist is that photons of light can impart momentum when they bounce off something. It’s not very much, but if you add a tremendous amount of photons, the impact can be significant. And because those photons are going the speed of light, the maximum speed for the spacecraft, in theory, is just shy of the speed of light (thanks relativity).
You can get those photons from the Sun, but you can also get them from a directed laser beam, designed to fill the sails with photons, without actually melting the spacecraft.
In the past, engineers have talked about solar sails that might be thousands of kilometers across, made of gossamer sheets of reflective fabric. Got that massive, complicated sail in your mind?
Now think smaller. The Starshot spacecraft will measure just a few meters across, with a thickness of just a few atoms. The sail would then pull a microscopic payload of instruments. A tiny chip, capable of gathering data and transmitting information – these are called Starchips. Not even enough room for water bear crew quarters.
A phased laser array, perhaps in the high desert of Chile, propels sails on their journey. Credit: Breakthrough Initiatives.
With such a low mass, a powerful laser should be able to accelerate them to 20% the speed of light, almost instantly, making a trip to Alpha Centauri only take about 20 years.
Since each Starshot might only cost a few dollars to make, the company could manufacture thousands and thousands, place them into orbit, and then start bugzapping them off to different stars.
There are, of course, some massive engineering hurdles to overcome.
The first is the density of the interstellar medium. Although it’s almost completely empty in between the stars, there are the occasional dust particles. Normally harmless, the Starshots would be smashing into them at 20% the speed of light, which would be catastrophic.
The second problem is that this is a one-way trip. Once it’s going 20% the speed of light, there’s no way to slow the spacecraft down again (unless the Alpha Centaurans have a braking system in place). Just imagine the motion blur and targeting problems when you’re trying to take photos at relativistic speeds.
The third problem, and this is a big one, is that the miniaturization of the spacecraft means that you can’t have a big transmitter. Communicating across the light years takes a LOT of power. Maybe they’ll connect up into some kind of array and share the power requirement, or use lasers to communicate back. Maybe they’ll relay the data back like a Voltron daisy chain.
Even though the idea of traveling to another star might seem overly ambitious today, this technology actually makes a lot of sense for exploration in our own Solar System. We could bugzap little spacecraft to Venus, Mars, the outer planets and their moons – even deep into the Kuiper Belt and the totally unexplored Oort cloud. We could have this whole Solar System on exploration lockdown in just a few decades.
Even if a mission to Alpha Centauri is currently science fiction, this miniaturization is going to be the way we learn more about the Solar System we live in. Let’s get going!
Artist's impression of the Earth scorched by our Sun as it enters its Red Giant Branch phase. Credit: Wikimedia Commons/Fsgregs
Since the beginning of human history, people have understood that the Sun is a central part of life as we know it. It’s importance to countless mythological and cosmological systems across the globe is a testament to this. But as our understand of it matured, we came to learn that the Sun was here long before us, and will be here long after we’re gone. Having formed roughly 4.6 bullion years ago, our Sun began its life roughly 40 million years before our Earth had formed.
Since then, the Sun has been in what is known as its Main Sequence, where nuclear fusion in its core causes it to emit energy and light, keeping us here on Earth nourished. This will last for another 4.5 – 5.5 billion years, at which point it will deplete its supply of hydrogen and helium and go through some serious changes. Assuming humanity is still alive and calls Earth home at this time, we may want to consider getting out the way!
The Birth of Our Sun:
The predominant theory on how our Sun and Solar System formed is known as Nebular Theory, which states that the Sun and all the planets began billions of years ago as a giant cloud of molecular gas and dust. Then, approximately 4.57 billion years ago, this cloud experienced gravitational collapse at its center, where anything from a passing star to a shock wave caused by a supernova triggered the process that led to our Sun’s birth.
Basically, this took place after pockets of dust and gas began to collect into denser regions. As these regions pulled in more and more matter, conservation of momentum caused them to begin rotating, while increasing pressure caused them to heat up. Most of the material ended up in a ball at the center while the rest of the matter was flattened out into a large disk that circled around it.
Young stars have a disk of gas and dust around them called a protoplanetary disk. Out of this disk planets are formed, and the presence of water ice in the disc affects where different types of planets form. Credit: NASA/JPL-Caltech
The ball at the center would eventually form the Sun, while the disk of material would form the planets. The Sun then spent the next 100,000 years as a collapsing protostar before temperature and pressures in the interior ignited fusion at its core. The Sun started as a T Tauri star – a wildly active star that blasted out an intense solar wind. And just a few million years later, it settled down into its current form.
Main Sequence:
For the past 4.57 billion years (give or take a day or two), the Sun has been in the Main Sequence of its life. This is characterized by the process where hydrogen fuel, under tremendous pressure and temperatures in its core, is converted into helium. In addition to changing the properties of its constituent matter, this process also produces a tremendous amount of energy. All told, every second, 600 million tons of matter are converted into neutrinos, solar radiation, and roughly 4 x 1027 Watts of energy.
Naturally, this process cannot last forever since it is dependent on the presence of matter which is being regularly consumed. As time goes on and more hydrogen is converted into helium, the core will continue to shrink, allowing the outer layers of the Sun to move closer to the center and experience a stronger gravitational force.
This will place more pressure on the core, which is resisted by a resulting increase in the rate at which fusion occurs. Basically, this means that as the Sun continues to expend hydrogen in its core, the fusion process speeds up and the output of the Sun increases. At present, this is leading to a 1% increase in luminosity every 100 million years, and a 30% increase over the course of the last 4.5 billion years.
The life cycle of a Sun-like star, from its birth on the left side of the frame to its evolution into a red giant on the right after billions of years. Credit: ESO/M. Kornmesser
Approximately 1.1 billion years from now, the Sun will be 10% brighter than it is today. This increase in luminosity will also mean an increase in heat energy, one which the Earth’s atmosphere will absorb. This will trigger a runaway greenhouse effect that is similar to what turned Venus into the terrible hothouse it is today.
In 3.5 billion years, the Sun will be 40% brighter than it is right now, which will cause the oceans to boil, the ice caps to permanently melt, and all water vapor in the atmosphere to be lost to space. Under these conditions, life as we know it will be unable to survive anywhere on the surface, and planet Earth will be fully transformed into another hot, dry world, just like Venus.
Red Giant Phase:
In 5.4 billion years from now, the Sun will enter what is known as the Red Giant phase of its evolution. This will begin once all hydrogen is exhausted in the core and the inert helium ash that has built up there becomes unstable and collapses under its own weight. This will cause the core to heat up and get denser, causing the Sun to grow in size.
It is calculated that the expanding Sun will grow large enough to encompass the orbit’s of Mercury, Venus, and maybe even Earth. Even if the Earth were to survive being consumed, its new proximity to the the intense heat of this red sun would scorch our planet and make it completely impossible for life to survive. However, astronomers have noted that as the Sun expands, the orbit of the planet’s is likely to change as well.
When the Sun reaches this late stage in its stellar evolution, it will lose a tremendous amount of mass through powerful stellar winds. Basically, as it grows, it loses mass, causing the planets to spiral outwards. So the question is, will the expanding Sun overtake the planets spiraling outwards, or will Earth (and maybe even Venus) escape its grasp?
K.-P Schroder and Robert Cannon Smith are two researchers who have addressed this very question. In a research paper entitled “Distant Future of the Sun and Earth Revisted” which appeared in the Monthly Notices of the Royal Astronomical Society, they ran the calculations with the most current models of stellar evolution.
According to Schroder and Smith, when the Sun becomes a red giant star in 7.59 billion years, it will start to lose mass quickly. By the time it reaches its largest radius, 256 times its current size, it will be down to only 67% of its current mass. When the Sun does begin to expand, it will do so quickly, sweeping through the inner Solar System in just 5 million years.
It will then enter its relatively brief (130 million year) helium-burning phase, at which point, it will expand past the orbit of Mercury, and then Venus. By the time it approaches the Earth, it will be losing 4.9 x 1020 tonnes of mass every year (8% the mass of the Earth).
But Will Earth Survive?:
Now this is where things become a bit of a “good news/bad news” situation. The bad news, according to Schroder and Smith, is that the Earth will NOT survive the Sun’s expansion. Even though the Earth could expand to an orbit 50% more distant than where it is today (1.5 AUs), it won’t get the chance. The expanding Sun will engulf the Earth just before it reaches the tip of the red giant phase, and the Sun would still have another 0.25 AU and 500,000 years to grow.
Artist’s impression of a Red giant star. Credit:NASA/ Walt Feimer
Once inside the Sun’s atmosphere, the Earth will collide with particles of gas. Its orbit will decay, and it will spiral inward. If the Earth were just a little further from the Sun right now, at 1.15 AU, it would be able to survive the expansion phase. If we could push our planet out to this distance, we’d also be in business. However, such talk is entirely speculative and in the realm of science fiction at the moment.
And now for the good news. Long before our Sun enters it’s Red Giant phase, its habitable zone (as we know it) will be gone. Astronomers estimate that this zone will expand past the Earth’s orbit in about a billion years. The heating Sun will evaporate the Earth’s oceans away, and then solar radiation will blast away the hydrogen from the water. The Earth will never have oceans again, and it will eventually become molten.
Yeah, that’s the good news… sort of. But the upside to this is that we can say with confidence that humanity will be compelled to leave the nest long before it is engulfed by the Sun. And given the fact that we are dealing with timelines that are far beyond anything we can truly deal with, we can’t even be sure that some other cataclysmic event won’t claim us sooner, or that we wont have moved far past our current evolutionary phase.
An interesting side benefit will be how the changing boundaries of our Sun’s habitable zone will change the Solar System as well. While Earth, at a mere 1.5 AUs, will no longer be within the Sun’s habitable zone, much of the outer Solar System will be. This new habitable zone will stretch from 49.4 AU to 71.4 AU – well into the Kuiper Belt – which means the formerly icy worlds will melt, and liquid water will be present beyond the orbit of Pluto.
Perhaps Eris will be our new homeworld, the dwarf planet of Pluto will be the new Venus, and Haumeau, Makemake, and the rest will be the outer “Solar System”. But what is perhaps most fascinating about all of this is how humans are even tempted to ask “will it still be here in the future” in the first place, especially when that future is billions of years from now.
Somehow, the subjects of what came before us, and what will be here when we’re gone, continue to fascinate us. And when dealing with things like our Sun, the Earth, and the known Universe, it becomes downright necessary. Our existence thus far has been a flash in the pan compared to the cosmos, and how long we will endure remains an open question.
The Messier 13 globular cluster, located in the Hercules constellation. Credit: Adam Block/Sid Leach/Mount Lemmon SkyCenter/University of Arizona
Welcome back to Messier Monday! Today, in our ongoing tribute to Tammy Plotner, we take a look at the M13 globular cluster, which is often referred to as the Great Globular Cluster in Hercules. Enjoy!
In the 18th century, French astronomer Charles Messier began cataloging all the “nebulous objects” he had come to find while searching the night sky. Having originally mistook these for comets, he compiled a list these objects in the hopes of preventing future astronomers from making the same mistake. In time, the list would include 100 objects, and would come to be known as the Messier Catalog to posterity.
One of these objects is M13 (aka. NGC 6205) a globular cluster located in the Hercules constellation. Located some 25,100 light-years away from Earth, this cluster is made up of 300,000 stars and occupies a region of space that measures 145 light-years in diameter. Given its sheer size and its location, it is often referred to as the “Great Hercules Cluster”.
Description:
This 11.65 billion year old formation of stars is one of the most impressive globular clusters in the northern hemisphere. Containing over 300,000 stars packed into a 145 light year sphere, the center of this glorious object is 500 times more concentrated than its outer perimeters. And out of all of those stars there stands one stranger – Barnard 29. This spectral type B2 star is a young, blue star that M13 is believed to have collected during one of its tours around the Milky Way Galaxy.
Other interesting finds include the 15 blue straggler star candidates and 10 other possible that have been spotted by the Hubble Space Telescope. The stars in the blue horizontal branch of M13 appeared to be centrally depleted relative to other stellar types and the blue stragglers in the combined sample are centrally concentrated relative to the older red giant stars.
The heart of the M13 Hercules Globular Cluster, viewed with the Hubble Space Telescope. Credit: ESA/NASA/HST
However, the Stromgren photometry work performed by Frank Grundah (et al.) suggests this is a normal occurrence in evolution. “We also note the existence of what appears to be two separate stellar populations on the horizontal branch of M13. Among other possibilities, it could arise as the result of differences in the extent to which deep mixing occurs in the precursor red giants.”
“One of the long-standing problems in modern astronomy is the curious division of Galactic globular clusters, the “Oosterhoff dichotomy,” according to the properties of their RR Lyrae stars. Here, we find that most of the lowest metallicity clusters, which are essential to an understanding of this phenomenon, display a planar alignment in the outer halo. This alignment, combined with evidence from kinematics and stellar population, indicates a captured origin from a satellite galaxy. We show that, together with the horizontal-branch evolutionary effect, the factor producing the dichotomy could be a small time gap between the cluster-formation epochs in the Milky Way and the satellite. The results oppose the traditional view that the metal-poorest clusters represent the indigenous and oldest population of the Galaxy.”
As to how old M13’s stars are, there is more than one answer. According the work of R. Glebocki (et al), stellar rotation within Messier 13 can also play a role in how the stars age. As they state in their 2000 research study, “Catalog of Projected Rotational Velocities”:
“Much theoretical and observational work about the role that rotation plays in stellar evolution has been done. Angular momentum is one of the fundamental parameters in the process of star formation as well as in early life of a star. A considerable amount of research has been done on the stellar axial rotational velocities. Clusters present unique possibility of determination of age of stars.”
Messier 13, as imaged by a DSLR camera. Credit: Wikipedia Commons/Rawastrodata
History of Observation:
M13 was originally discovered by Edmond Halley in 1714. In his notes, he wrote of the cluster: “This is but a little Patch, but it shews it self to the naked Eye, when the Sky is serene and the Moon absent.”
On June 1st, 1764, Charles Messier officially catalogued the star cluster as item 13. As he described it at the time:
“In the night of June 1 to 2, 1764, I have discovered a nebula in the girdle of Hercules, of which I am sure it doesn’t contain any star; having examined it with a Newtonian telescope of four feet and a half [FL], which magnified 60 times, it is round, beautiful & brilliant, the center brighter than the borders: One perceives it with an ordinary [non-achromatic] refractor of one foot [FL], it may have a diameter of three minutes of arc: It is accompanied by two stars, the one and the other of the ninth magnitude, situated, the one above and the other below the nebula, & little distant. I have determined its position at its passage of the Meridian, and compared with the star Epsilon Herculis; its right ascension has been concluded to be 248d 18′ 48″, and its declination 36d 54′ 44″ north. It is reported in the Philosophical Transactions, no. 347, page 390, that Mr. Halley discovered by hazard that nebula in 1714: it is, he says, almost on a straight line with Zeta and Eta according to Bayer, a bit closer to the star Zeta than to Eta, & when comparing its situation between the stars, its place is rather close to Scorpius 26d 1/2 with 57 degrees Northern [ecliptic] latitude, it is nothing but a small patch; but one sees it well without a telescope when the weather is fine, and if there is no light of the moon.”
Although Sir William Herschel would soon enough resolve it into stars and again by his son and many others, no one described the history of this object more eloquently than Admiral Smyth:
“A large cluster, or rather ball of stars, on the left buttock of Hercules, between Zeta and Eta; the place of which is differentiated from Eta Herculis, from which it lies south, a little westly, and 3deg 1/2 distant. This superb object blazes up in the centre, and has numerous outliers around its attenuated disc. It was accidentally hit upon by Halley, who says, “This is but a little patch, but it shows itself to the naked eye, when the sky is serene, and the moon absent.” The same paper, in describing this as the sixth and last of the nebulae known in 1716, wisely admits, “there are undoubtedly more of these which have not yet come to our knowledge:” ere half a century passed, Messier contributed his 80 or 90 in the Catalogue of 103; and before the close of that century WH [William Herschel] alone had added to the above 6, no fewer than 2500; and his son, in re-examining these, added 520 more! In my own refractor its appearance was something like the annexed diagram; but I agree with Dr. Nichol, that no plate can give a fitting representation of this magnificent cluster. It is indeed truly glorious, and enlarges on the eye by studying gazing. “Perhaps,” adds the Doctor, “no one ever saw it for the first time through a telescope, without uttering a shout of wonder.” This brilliant cluster was discovered by Halley in 1714; and fifty years afterwards it was examined by M. Messier, with his 4-foot Newtonian, under a power of 60, and described as round, beautiful, and brilliant; but, “ferret” as he was in these matters, he adds, “Je me suis assuré qu’elle ne contient aucune étoile.” This is rather startling, since the slightest optical aid enables the eye to resolve it into an extensive and magnificent mass of stars, with the most compressed part densely compacted and wedged together under unknown laws of aggregation. In 1787, Sir William Herschel pronounced it “a most beautiful cluster of stars, exceedingly compressed in the middle, and very rich.” It has been recently viewed in the Earl of Rosse’s new and powerful telescope, when the components were more distinctly separated, and brighter, than had been anticipated; and there were singular fringed appendages to the globular figure, branching out into the surrounding space, so as to form distinct marks among the general outliers.”
And so Messier 13 has been part of our imaginations for many years. And in 1974, a message was sent from Arecibo Observatory designed to communicate the existence of human life to hypothetical extraterrestrials. Known as the “Aricebo Message”, it was expected that this communique had a better chance of finding intelligent life since the odds of it existing within this massive cluster of stars was greater than elsewhere.
Messier 13, located in the Hercules constellation. Credit: IAU/Sky&Telescope magazine/Roger Sinnott & Rick Fienberg
Locating Messier 13:
To locate M13, all one needs to know is the “Keystone” asterism of Hercules. While this lopsided rectangle isn’t particularly bright, once you understand where to find it, you’ll be able to spot it even under relatively light-polluted skies. Both Vega (in the constellation of Lyra) and Arcturus (in Bootes) are very bright stars and the keystone is about 1/3 the distance between them.
Once you locate it, always remember that Messier 13 is on the leading western side – no matter what position Hercules may be in. By just generally aiming your binoculars in the center of the two stars on the western side, you can’t miss this big, bright globular cluster. When using a finderscope, aim slightly north of the center point and you’ll easily spot it as well. From a dark sky location, M13 can often be seen unaided as a small, fuzzy spot on the sky.
And here are the quick facts on the Great Hercules Cluster to help you get started:
Object Name: Messier 13 Alternative Designations: M13, NGC 6205, the “Great Hercules Cluster” Object Type: Class V Globular Cluster Constellation: Hercules Right Ascension: 16 : 41.7 (h:m) Declination: +36 : 28 (deg:m) Distance: 25.1 (kly) Visual Brightness: 5.8 (mag) Apparent Dimension: 20.0 (arc min)
The northern constellation Auriga, showing the brightest stars of Capella, Menkalinan, and proximate Deep Sky Objects. Credit: stargazerslounge.com
Welcome back to Constellation Friday! Today, in honor of our dear friend and contributor, Tammy Plotner, we examine the Auriga constellation. Enjoy!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of the then-known 48 constellations. His treatise, known as the Almagest, would serve as the authoritative source of astronomy for over a thousand years to come. Since the development of modern telescopes and astronomy, this list has come to be expanded to include the 88 constellation that are recognized by the International Astronomical Union (IAU) today.
One of these is the constellation of Auriga, a beautiful pentagon-shaped collection of stars that is situated just north of the celestial equator. Along with five other constellations that have stars in the Winter Hexagon asterism, Auriga is most prominent during winter evenings in the Northern Hemisphere. Auriga also belongs to the Perseus family of constellations, together with Andromeda, Cassiopeia, Cepheus, Cetus, Lacerta, Pegasus, Perseus, and Triangulum.
Mars from orbit. Valles Marineris and Volcanic region
Given it’s similarities to Earth, Mars is often referred to as “Earth’s Twin”. Like Earth, Mars is a terrestrial planet, which means it is composed largely of silicate rock and minerals that are differentiated into a core, mantle and crust. It is also located within the Sun’s “Goldilocks Zone” (aka. habitable zone), has polar ice caps, and once had flowing water on its surface. But beyond these, Mars and Earth are very different worlds.
In addition to their stark contrasts in temperature, surface conditions, and exposure to harmful radiation, Mars also takes a significantly longer time to complete a single orbit of the Sun. In fact, a year on Mars is almost twice as long as a year here on Earth – lasting 686.971 days, which works out to about 1.88 Earth years. And in the course of that orbit, the planet undergoes some rather interesting changes.
The M12 globular cluster, image taken by the Hubble Space Telescope. Credit: NASA/Hubble Heritage Team /AURA/STScI
Welcome back to another edition of Messier Monday! Today, we continue in our tribute to Tammy Plotner with a look at the M12 globular cluster!
In the 18th century, French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky which he originally mistook for comets. After realizing his mistake, he began compiling a list of these objects in order to ensure that other astronomers did not make the same error. In time, this list would include 100 objects, and would come to be known as the Messier Catalog to posterity.
One the many objects included in this is Messier 12 (aka. M12 or NGC 6218), a globular cluster located in the Ophiuchus constellation some 15,700 light-years from Earth. M12 is positioned just 3° from the cluster M10, and the two are among the brightest of the seven Messier globulars located in Ophiuchus. It is also interesting to note that M12 is approaching our Solar System at a velocity of 16 km/s.
The Aries constellation and nearby Deep Sky Objects. Credit: thinglink.com
Welcome back to constellation Friday! Today, in honor of our dear friend and contributor, Tammy Plotner, we examine the Aries constellation. Enjoy!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of the then-known 48 constellations. His treatise, known as the Almagest, would serve as the authoritative source of astronomy for over a thousand years to come. Since the development of modern telescopes and astronomy, this list has come to be expanded to include the 88 constellation that are recognized by the International Astronomical Union (IAU) today.
Of these constellations, Aries – named in honor of the Ram from classical Greek mythology – is featured rather prominently. This faint constellation has deep roots, and is believed to date all the way back to the astrological systems of the ancient Babylonians. Positioned on the ecliptic plane, it is bordered by constellations of Perseus, Triangulum, Pisces, Cetus and Taurus, and is also the traditional home of the vernal equinox.
