Guide to Space Archives

April 20, 2015February 27, 2017 by Fraser Cain

Is There a Mirror Universe?

Could there be a mirror universe, where everything is backwards – and everybody has goatees? How badly do you need to bend the laws of physics to make this happen?

One of the great mysteries in cosmology is why the Universe is mostly matter and not antimatter. If you want to learn more about that specific subject, you can click here and watch an episode all about that.

During the Big Bang, nearly equal amounts of matter and antimatter were created, and subsequently annihilated. Nearly equal. And so we’re left with a Universe made of matter.

But could there be antimatter stars out there? With antimatter planets in orbit. Could there be a backwards Universe that operates just like our regular Universe, but everything’s made of antimatter? And if it’s out there, does it have to be evil? Do they only know how to conquer? Does everyone, even the antimatter babies and ladies, have handsome goatees? How about sashes? I hear they’re big on sashes. OOH and daggers. Gold daggers with little teensy antimatter emeralds and rubies.

Antimatter, without the goatee, was theorized in 1928 by Paul Dirac, who realized that one implication of quantum physics was that you could get electrons that had a positive charge instead of a negative charge. They were discovered by Carl D. Anderson just 4 years later, which he named “positron” for positive electron.

We believe he was clearly snubbing Dirac, by not naming them the “Diracitron”, alternately they were saving that name for a giant Japanese robot.

These antiparticles are created through high energy particle collisions happening naturally in the Universe, or unnaturally inside our “laugh in the face of God and nature” particle accelerators. We can even detect the annihilation out there in the Universe where matter and antimatter crash into each other.

Physicists have discovered a range of anti-particles. Anti-protons, anti-neutrons, anti-hydrogen, anti-helium. To date, there’s been no evidence of any goatees or sashes. Naturally, they wondered what might happen if the balance of the Universe was flipped. What if we had a Universe made out of mostly antimatter? Would it still… you know, work? Could you have antimatter stars, antimatter planets, and even those antimatter people we mentioned?

When physics swap out matter for anti-matter in their equations, they call it charge conjugation. It turns out, no. If you reversed the charge of all the particles in the Universe, it wouldn’t evolve in the same way as our “plain old non-sashed” Universe.

To fix this problem, physicists considered the implications if you had an actual mirror Universe, where all the particles behaved as if they were mirror images of themselves. This sounds a little more in line with our “Through a mirror, darkly” goatee and sash every day festival universe. This is all the bits backwards. Spin, charge, velocity, the works. They called this parity inversion. So, would this work?

Again, it turns out that the answer is no. It would almost work out, but there’s a tendency for the weak nuclear force, the one the governs nuclear decay to violate this idea of parity inversion. Even in a mirror Universe, the weak nuclear force is left-handed. Dammit, weak nuclear force, get your act together, if not just for the sake of the costumes and cooler bridge lighting.

What matter and antimatter might look like annihilating one another. Credit: NASA/CXC/M. Weiss

What if you reversed both the charge and the parity at the same time? What if you had antimatter in a mirror Universe? Physicists called this charge-parity symmetry, or CP symmetry.

In a dazzling experiment and absolute “what if” one-upmanship exercise by James Cronin and Val Fitch in 1964. They demonstrated that no, you can’t have a mirror-antimatter Universe evolve with our physical laws. This experiment won the Nobel Prize in 1980.

Physicists had one last trick up their sleeves. It turns out that if you reverse time itself as well as making everything out of antimatter and holding it up to a mirror, you get true symmetry. All the physical lays are preserved, and you’d get a Universe that would look exactly like our own.

It turns out we could live in a mirror Universe, as long as you were willing to reverse the charge of every particle and run time backwards. And if you did, it would be indistinguishable from the Universe we actually live in. Now, if you’ll excuse me, I think I need to call my tailor, I hear sashes are going to be huge this year.

So what do you think, do we live in the real Universe or the mirror Universe? Tell us in the comments below.

April 16, 2015February 27, 2017 by Fraser Cain

Does the Solar System Line Up with the Milky Way?

Have you ever wondered if the Solar System and the Milky Way line up perfectly, like plates spinning within plates? This is something you can test out for yourself.

We love to answer your questions, this one is clearly a fan favorite in the category of the “Wouldn’t it be crazy if…”. Our Solar System is disk shaped, with all the planets orbiting around the Sun in roughly the same plane. AND the Milky Way is also disk shaped, with all the stars orbiting around and around the center of the galaxy. Wouldn’t it be crazy if the Milky Way and the Solar System lined up? Why would that happen?

Do all Solar Systems line up with the Milky Way, like plates spinning on plates spinning on plates? And those plates are on smaller plates. It’s spinning plates all the way down.

The answer is unfortunately “no”, because yes, it is cool when things line up. At this point, I know you’re immediately thinking I’m in the pocket of “Big Plate shape”, but I can assure you that’s not the truth. The Nibiruans, CIA and Big Dental pay much better than those cheap disc jerks have ever ponied up.

The good news is, you don’t have to take science’s word for this. In fact, you can check this out for yourself. If you’ve spent any time watching the sky, you’ll know that the Sun takes roughly the same path across the sky every day. It rises in the East, travels across the sky, and then sets in the West. For me here in Canada, the Sun rises over there in the Winter, it trundles sadly across the horizon to the South, and then sets in the West.

If you live on the equator, you might see the Sun pass right overhead during the day. And if you live in the Southern Hemisphere, you might see the Sun go across the North in the sky. As we spin, the Sun always goes along a predictable line. We can always point at it and say “There’s the center of our solar system”. The Moon takes the same path, and so do the rest of the planets. It’s the plane of the ecliptic, and we’re embedded right in the middle of it. If you get to dark enough skies, you can see the Milky Way. It’s that faint cloudy band that goes across the sky. If the Solar System and the Milky Way had their Frisbees lined up, we could see the Sun, Moon and planets always be in front of the Milky Way.

But they’re not, the Milky Way is actually inclined from the celestial equator at 63-degrees. They cross each other through the constellations of Monoceros and Aquila-Serpens-Ophiuchus. For me, the Milky Way starts over there and ends up over there. The plane of the ecliptic and the Milky Way make a big cross in the sky. The orientation between the Solar System and the Milky Way is coincidence. They just happen to be perpendicular-ish. But they could also just happen to line up, and that would be nothing more than a coincidence too.

The Milky Way and the Solar System aren’t lined up. They couldn’t be any more un-lined up if they tried. Here’s the Milky Way, here’s the Solar System. I’m a Power Ranger. So, I’m sorry, but just won’t be able to use that to justify your cosmic theories about the return of the Flying Spaghetti Monster. Or alternately… like any good conspiracy style thinking…

Good news! The Milky Way and Solar System are almost perpendicular and clearly that near-opposite alignment generates some kind of woogly ethereal gyroscopic metastatic force that clearly is causing your gluten sensitivity and heralds the coming of FSM. What magical effect is this perpendicular alignment causing for you? Tell us in the comments below.

April 13, 2015February 27, 2017 by Fraser Cain

How Do Black Holes Evaporate?

Nothing lasts forever, not even black holes. According to Stephen Hawking, black holes will evaporate over vast periods of time. But how, exactly, does this happen?

The actor Stephen Hawking is best known for his cameo appearances in Futurama and Star Trek, you might surprised to learn that he’s also a theoretical astrophysicist. Is there anything that guy can’t do?

One of the most fascinating theories he came up with is that black holes, the Universe’s swiffer, can actually evaporate over vast periods of time.

Quantum theory suggests there are virtual particles popping in and out of existence all the time. When this happens, a particle and its antiparticle appear, and then they recombine and disappear again.

When this takes place near an event horizon, strange things can happen. Instead of the two particles existing for a moment and then annihilating each other, one particle can fall into the black hole, and the other particle can fly off into space. Over vast periods of time, the theory says that this trickle of escaping particles causes the black hole to evaporate.

Wait, if these virtual particles are falling into the black hole, shouldn’t that make it grow more massive? How does that cause it to evaporate? If I add pebbles to a rock pile, doesn’t my rock pile just get bigger?

It comes down to perspective. From an outside observer watching the black hole’s event horizon, it appears as if there’s a glow of radiation coming from the black hole. If that was all that was happening, it would violate the law of thermodynamics, as energy can neither be created nor destroyed. Since the black hole is now emitting energy, it needs to have given up a little bit of its mass to provide it.

Let’s try another way to think about this. A black hole has a temperature. The more massive it is, the lower its temperature, although it’s still not zero.

From now and until far off into the future, the temperature of the largest black holes will be colder than the background temperature of the Universe itself. Light from the cosmic microwave background radiation will fall in, increasing its mass.

Viewed in visible light, Markarian 739 resembles a smiling face. Inside are two supermassive black holes, separated by about 11,000 light-years. The galaxy is 425 million light-years away from Earth. Credit: Sloan Digital Sky Survey

Now, fast forward to when the background temperature of the Universe drops below even the coolest black holes. Then they’ll slowly radiate heat away, which must come from the black hole converting its mass into energy.

The rate that this happens depends on the mass. For stellar mass black holes, it might take 10^67 years to evaporate completely.

For the big daddy supermassive ones at the cores of galaxies, you’re looking at 10^100. That’s a one, followed by 100 zero years. That’s huge number, but just like any gigantic and finite number, it’s still less than infinity. So over an incomprehensible amount of time, even the longest living objects in the Universe – our mighty black holes – will fade away into energy.

One last thing, the Large Hadron Collider might be capable of generating microscopic black holes, which would last for a fraction of a second and disappear in a burst of Hawking radiation. If they find them, then Hawking might want to the acting on hold and focus on physics.

Nothing is eternal, not even black holes. Over the longest time frames we’re pretty sure they’ll evaporate away into nothing. The only way to find out is to sit back and watch, well maybe it’s not the only way.

Does the idea of these celestial nightmares evaporating fill you with existential sadness? Feel free to share your thoughts with others in the comments below.

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April 9, 2015February 27, 2017 by Fraser Cain

How Quickly Does a Supernova Happen?

When a massive star reaches the end of its life, it can explode as a supernova. How quickly does this process happen?

Our Sun will die a slow sad death, billions of years from now when it runs out of magic sunjuice. Sure, it’ll be a dramatic red giant for a bit, but then it’ll settle down as a white dwarf. Build a picket fence, relax on the porch with some refreshing sunjuice lemonade. Gently drifting into its twilight years, and slowly cooling down until it becomes the background temperature of the Universe.

If our Sun had less mass, it would suffer an even slower fate. So then, unsurprisingly, if it had more mass it would die more quickly. In fact, stars with several times the mass of our Sun will die as a supernova, exploding in an instant. Often we talk about things that take billions of years to happen on the Guide to Space. So what about a supernova? Any guesses on how fast that happens?

There are actually several different kinds of supernovae out there, and they have different mechanisms and different durations. But I’m going to focus on a core collapse supernova, the “regular unleaded” of supernovae. Stars between 8 and about 50 times the mass of the Sun exhaust the hydrogen fuel in their cores quickly, in few short million years.

Just like our Sun, they convert hydrogen into helium through fusion, releasing a tremendous amounts of energy which pushes against the star’s gravity trying to collapse in on itself. Once the massive star runs out of hydrogen in its core, it switches to helium, then carbon, then neon, all the way up the periodic table of elements until it reaches iron. The problem is that iron doesn’t produce energy through the fusion process, so there’s nothing holding back the mass of the star from collapsing inward.
… and boom, supernova.

The outer edges of the core collapse inward at 70,000 meters per second, about 23% the speed of light. In just a quarter of a second, infalling material bounces off the iron core of the star, creating a shockwave of matter propagating outward. This shockwave can take a couple of hours to reach the surface.

Type II Supernovae — SN 1987A, an example of a Type II-P Supernova

As the wave passes through, it creates exotic new elements the original star could never form in its core. And this is where we get all get rich. All gold, silver, platinum, uranium and anything higher than iron on the periodic table of elements are created here. A supernova will then take a few months to reach its brightest point, potentially putting out as much energy as the rest of its galaxy combined.

Supernova 1987A, named to commemorate the induction of the first woman into the Rock and Roll Hall of Fame, the amazing Aretha Franklin. Well, actually, that’s not true, it was the first supernova we saw in 1987. But we should really name supernovae after things like that. Still, 1987A went off relatively nearby, and took 85 days to reach its peak brightness. Slowly declining over the next 2 years. Powerful telescopes like the Hubble Space Telescope can still see the shockwave expanding in space, decades later.

Evolution of a Type Ia supernova. Credit: NASA/CXC/M. Weiss

Our “regular flavor” core collapse supernova is just one type of exploding star. The type 1a supernovae are created when a white dwarf star sucks material off a binary partner like a gigantic parasitic twin, until it reaches 1.4 times the mass of the Sun, and then it explodes. In just a few days, these supernovae peak and fade much more rapidly than our core collapse friends.

So, how long does a supernova take to explode? A few million years for the star to die, less than a quarter of a second for its core to collapse, a few hours for the shockwave to reach the surface of the star, a few months to brighten, and then just few years to fade away.

Which star would you like to explode? Tell us in the comments below.

Thanks for watching! Never miss an episode by clicking subscribe. Our Patreon community is the reason these shows happen. We’d like to thank David Hall and the rest of the members who support us in making great space and astronomy content. Members get advance access to episodes, extras, contests, and other shenanigans with Jay, myself and the rest of the team. Want to get in on the action? Click here.

April 8, 2015February 7, 2022 by Paul Patton

Beyond “Fermi’s Paradox” II: Questioning the Hart-Tipler Conjecture

Artist's impression of The Milky Way Galaxy. Based on current estimates and exoplanet data, it is believed that there could be tens of billions of habitable planets out there. Credit: NASA

Welcome back to our Fermi Paradox series, where we take a look at possible resolutions to Enrico Fermi’s famous question, “Where Is Everybody?” Today, we examine the possibility that the reason we’ve found no evidence of alien civilizations is because there are none out there.

It’s become a legend of the space age. The brilliant physicist Enrico Fermi, during a lunchtime conversation at Los Alamos National Laboratory in 1950, is supposed to have posed a conundrum for proponents of the existence of extraterrestrial civilizations.

If space traveling aliens exist, so the argument goes, they would spread through the galaxy, colonizing every habitable world. They should then have colonized Earth. They should be here, but because they aren’t, they must not exist.

This is the argument that has come to be known as “Fermi’s paradox”. The problem is, as we saw in the first installment, Fermi never made it. As his surviving lunch companions recall (Fermi himself died of cancer just four years later, and never published anything on the topic of extraterrestrial intelligence), he simply raised a question, “Where is everybody?” to which there are many possible answers.

April 7, 2015February 7, 2022 by Paul Patton

Beyond “Fermi’s Paradox” I: A Lunchtime Conversation- Enrico Fermi and Extraterrestrial Intelligence

Nuclear physicist Enrico Fermi won the 1938 Nobel Prize for a technique he developed to probe the atomic nucleus. He led the team that developed the world's first nuclear reactor, and played a central role in the Manhattan Project that developed the atomic bomb during World War II. In the debate over extraterrestrial intelligence, he is best known for posing the question 'Where is everybody?' during a lunchtime discussion at Los Alamos National Laboratory. His question was seen as the basis for the "Fermi Paradox". Credit: Smithsonian Institution Archives.

Welcome back to our Fermi Paradox series, where we take a look at possible resolutions to Enrico Fermi’s famous question, “Where Is Everybody?” Today, we examine the lunchtime conversation that started it all!

It’s become a kind of legend, like Newton and the apple or George Washington and the cherry tree. One day in 1950, the great physicist Enrico Fermi sat down to lunch with colleagues at the Fuller Lodge at Los Alamos National Laboratory in New Mexico and came up with a powerful argument about the existence of extraterrestrial intelligence, the so-called “Fermi paradox”.

But like many legends, it’s only partly true. Robert Gray explained the real history in a recent paper in the journal Astrobiology. Enrico Fermi was the winner of the 1938 Nobel Prize for physics, led the team that developed the world’s first nuclear reactor at the University of Chicago, and was a key contributor to the Manhattan Project that developed the atomic bomb during World War II. The Los Alamos Lab where he worked was founded as the headquarters of that project.

April 6, 2015February 27, 2017 by Fraser Cain

How Can Black Holes Shine?

We hear that black holes absorb all the light that falls into them. And yet, we hear of black holes shining so brightly we can see them halfway across the Universe. What’s going on? Which is it?

I remember back to a classic episode of the Guide to Space, where I provided an extremely fascinating and concise explanation for what a quasar is. Don’t recall that episode? Well, it was super. Just super. Alright slackers, let’s recap.

Quasars are the brightest objects in the Universe, visible across billions of light years. Likely blanching life from everything in the path of the radiation beam from its lighthouse of death. They occur when a supermassive black hole is actively feeding on material, pouring out a mountain of radiation. Black holes, of course, are regions of space with such intense gravity where nothing, not even light itself, can escape.

But wait, not so fast “recap” Fraser Cain. I call shenanigans. If black holes absorb all the radiation that falls into them, how can they be bright?

You, Fraser Cain of days of yore, cannot have it both ways. It’s either a vortex of total destruction gobbling all the matter and light that fall into them OR alternately light can escape, which still sounds good. I mean, it could be WHERE NO STUFF CAN ESCAPE, except light.

If you’ll admit that you of the past was wrong, we’ll put you in the temporal cone of shame and move on with the episode. Right? Right? Wrong.

Let’s review. Black holes are freaky complicated beasts, with many layers. And I don’t mean that in some abstract Choprian “many connections on many different levels”. They’re a gobstopper from a Sam Neill Event Horizon style hellscape. Let’s take a look at the anatomy of a black hole, and everything should fall into place, including the terror.

At the very heart of the black hole is the singularity. This is the region of compressed matter that used to be a star, or in the case of a supermassive black hole, millions or billions of times the mass of a star. Astronomers have no idea what the singularity looks like or behaves, because our understanding of physics completely breaks down, along with the rest of our brains.

Illustration of Cygnus X-1, another stellar-mass black hole located 6070 ly away. (NASA/CXC/M.Weiss)

It’s possible that the singularity is a sphere of exotic matter, or maybe it’s constantly compressing down into an infinitely small size. It could also be a pork pie. We’ll never know, because nothing goes fast enough to escape from a black hole, not even light.

Maybe you’d need to be going 10 times the speed of light to escape. Or maybe a trillion times the speed of light. Which makes it easy; as far as we can tell, nothing can go faster than the speed of light, and so nothing is escaping.

As you get further from the singularity, the force of gravity decreases. Initially, it’ll still requires that you go faster than light. You’ll finally reach a very specific point where the escape velocity is exactly the speed of light. This is the event horizon, and it’s a different distance from the singularity with every black hole. That’s the line. Within the event horizon, the light is doomed, outside the event horizon, it can escape. This is the hard candy shell surrounding the chocolately unimaginable nightmare of physics.

So when see bright black holes, like a quasar, we’re not actually seeing light coming from inside the black hole itself or reflected of its surface. What we’re seeing is the material that’s piling up just outside the event horizon. For all its voracious hunger, a black hole’s gravitational eyes are much bigger than its stomach, and it can only feed so quickly. Excess stuff piles up around the black hole’s face and forms a vast disk of material, just like me at a Pizza Hut’s $5 all you can eat buffet. This pizza heats up until it’s like the core of a star, and starts blasting out radiation into space.

A WFPC2 image of a spiral-shaped disk of hot gas in the core of active galaxy M87. HST measurements show the disk is rotating so rapidly it contains a massive black hole at its hub.

Everything I’ve said is for non-spinning black holes, by the way. Physicists will always make this point with great emphasis. Stay your angry comments astrophysicists, for I have said the magic stone-cutter appeasement code-word, “Non-rotating”.

Of course, black holes do rotate, and can rotate at nearly the speed of light. And this rotation changes the nature of the black hole’s event horizon in ways that make difficult math even harder. All this spinning generates powerful magnetic fields around the black hole, which focuses jets of material that blast out for hundreds of thousands of light-years. When we see these bright quasars, we’re staring right at these jets with our delicate little eyeballs.

So how can we see light coming from black holes when black holes absorb all light? It’s not coming from black holes. It’s coming from the super-heated region of junk all around the black hole. And still, anything that falls through the event horizon, whether it be light, junk, you, me or Grumpy Cat it will never been seen again.

What’s your favorite sci-fi black hole? Tell us in the comments below.

Thanks for watching! Never miss an episode by clicking subscribe. Our Patreon community is the reason these shows happen. We’d like to thank Marcel-jan Krijgsman and the rest of the members who support us in making great space and astronomy content. Members get advance access to episodes, extras, contests, and other shenanigans with Jay, myself and the rest of the team. Want to get in on the action? Click here.

April 1, 2015December 23, 2015 by Matt Williams

A Red Moon – NOT a Sign of the Apocalypse!

Composite picture of a dark red Moon during a total lunar eclipse. Credit: NASA/ Johannes Schedler (Panther Observatory)

On most evenings, the Moon will appear as a bright yellow or white color in the night sky. But on occasion, the Moon can turn a beautiful and dramatic red, coppery color. Naturally, there are a number of superstitions associated with this stellar event. But to modern astronomers, a Red Moon is just another fascinating phenomenon that has a scientific explanation.

Since the earliest days of recorded history, the Moon has been believed to have a powerful influence over human and animal behavior. To the Romans, staring at a full Moon was thought to drive a person crazy – hence the term “lunatic”. Farmers in the past would plant their crops “by the moon”, which meant sowing their seeds in accordance with the Moon’s phases in the hopes of getting a better harvest.

So naturally, when the Moon turned red, people became wary. According to various Biblical passages, a Blood Moon was thought to be a bad omen. But of course, the Moon turns red on a semi-regular basis, and the world has yet to drown in fire. So what really accounts for a “Red Moon?” What causes Earth’s only satellite to turn the color of blood?

Ordinarily, the Moon appears as it does because it is reflecting light from the Sun. But on occasion, it will darken and acquire either a golden, copper, or even rusty-red color.

There are few situations that can cause a red Moon. The most common way to see the Moon turn red is when the Moon is low in the sky, just after moonrise or before it’s about to set below the horizon. Just like the Sun, light from the Moon has to pass through a larger amount of atmosphere when it’s down near the horizon, compared to when it’s overhead.

The Earth’s atmosphere can scatter sunlight, and since moonlight is just scattered sunlight, it can scatter that too. Red light can pass through the atmosphere and not get scattered much, while light at the blue end of the spectrum is more easily scattered. When you see a red moon, you’re seeing the red light that wasn’t scattered, but the blue and green light have been scattered away. That’s why the Moon looks red.

The second reason for a red Moon is if there’s some kind of particle in the air. A forest fire or volcanic eruption can fill the air with tiny particles that partially obscure light from the Sun and Moon. Once again, these particles tend to scatter blue and green light away, while permitting red light to pass through more easily. When you see a red moon, high up in the sky, it’s probably because there’s a large amount of dust in the air.

Depiction of the Sun's rays turning the Moon red. Image Credit: NASA/Mars Exploration — *Depiction of the Sun’s rays turning the Moon red. Image Credit: NASA/Mars Exploration*

A third – and dramatic – way to get a red Moon is during a lunar eclipse. This happens when the Moon is full and passes into Earth’s shadow (also known as the umbra), which darkens it. At that point, the Moon is no longer being illuminated by the Sun. However, the red light passing through the Earth’s atmosphere does reach the Moon, and is thus reflected off of it.

For those observing from the ground, the change in color will again be most apparent when the Moon appears low in the night sky, just after moonrise or before it’s about to set below the horizon. Once again, this is because our heavy atmosphere will scatter away the blue/green light and let the red light go straight through.

The reddish light projected on the Moon is much dimmer than the full white sunlight the Moon typically reflects back to us. That’s because the light is indirect and because the red-colored wavelengths are only a part of what makes up the white light from the sun that the Moon usually receives.

In other words, when you see a red Moon, you’re seeing the result of blue and green light that has been scattered away, and the red light remaining.

Path of the Moon through Earth's umbral and penumbral shadows during the Total Lunar Eclipse of April 15, 2014. Image Credit: NASA/Eclipse — *Path of the Moon through Earth’s umbral and penumbral shadows during the Total Lunar Eclipse of April 15, 2014. Image Credit: NASA/Eclipse Website*

And that’s the various ways how we get a Red Moon in the night sky. Needless to say, our ancient forebears were a little nervous about this celestial phenomenon occurrence.

For example, Revelations 6:12/13 says that a Red Moon is a sign of the apocalypse: “When he opened the sixth seal, I looked, and behold, there was a great earthquake, and the sun became black as sackcloth, the full moon became like blood, and the stars of the sky fell to the earth as the fig tree sheds its winter fruit when shaken by a gale.”

But rest assured that if you see one, it’s not the end of the world. The Sun and Moon will rise again. And be sure to check out this Weekly Space Hangout, where the April 4th eclipse is discussed:

We have covered lunar eclipses many times on Universe Today, and often explain the red Moon phenomenon. Here’s another good explanation of the science behind a Red Moon, and why the recent series of lunar eclipses in 2014 and 2015 (known as a tetrad) do not mean anything apocalyptic, and here’s another article about how to see a lunar eclipse. Here’s an article that includes a stunning array of images of the Moon during an eclipse in 2014.

Of course, NASA has some great explanations of the red Moon effect during a lunar eclipse. Here’s another one.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

Sources: NASA Science: Lunar Eclipse, NASA: Mars Exploration, Discovery News, NASA: Eclipse Website

March 30, 2015February 27, 2017 by Fraser Cain

How Dense is the Asteroid Belt?

We’ve seen way too many science fiction episodes that show asteroid belts as dense fields of tumbling boulders. How dense is the asteroid belt, and how to spacecraft survive getting through them?

For the purposes of revenue, lazy storytelling, and whatever it is Zak Snyder tells himself to get out of bed in the morning, when it comes to asteroids, Science fiction and video games creators have done something of disservice to your perception of reality.

Take a fond trip down sci-fi memory lane, and think about the time someone, possibly you, has had to dogfight or navigate through yet another frakkin’ asteroid belt. Huge space rocks tumbling dangerously in space! Action! Adventure! Only the skilled pilot, with her trusty astromecha-doplis ship can maneuver through the dense cluster of space boulders, dodging this way and that, avoiding certain collision.

And then she shoots her pew pew laser breaking up larger asteroids up into smaller ones, possibly obliterating them entirely depending on the cg budget. Inevitably, there’s bobbing and weaving. Pursuit craft will clip their wings on asteroids, spinning off into nearby tango. Some will fly straight into a space boulder.

Finally you’ll thread the needle on a pair of asteroids and the last ship of the whatever they’re called clicky clacky mantis Zorak bug people will try and catch you, but he/it won’t be quite so lucky. Poetically getting squashed like… a… bug. Sackhoff for the win, pilot victorious.

Okay, you probably knew the laser part is totally fake. I mean, everybody knows you can’t hear sounds in space. Outside of Starbuck being awesome, is that at all realistic? And if so, how does NASA maneuver unmanned spacecraft through that boulder-strewn grand canyon death trap to reach the outer planets?

The asteroid belt is a vast region between the orbits of Mars and Jupiter. Our collection of space rocks starts around 300 million kilometers from the Sun and ends around 500 million kilometers. The first asteroid, the dwarf planet Ceres which measures 950 km across, was discovered in 1801, with a “That’s funny.”. Soon after astronomers turned up many more small objects orbiting in this region at the “Oooh neat!” stage.

Artist’s concept of Dawn in its survey orbit at dwarf planet Ceres. Credit: NASA/JPL-Caltech

They realized it was a vast belt of material orbiting the Sun, with I suspect a “We’re all gonna die.”. To date, almost half a million asteroids have been discovered, most of which are in the main belt.

As mentioned in a another video, gathering up all the material in the asteroid belt and gluing it together makes a mass around 4% of the Moon. So, in case one of your friends gets excited and suggests it was a failed planet, you can bust out that stat and publicly shame them for being so 1996, Goodwill Hunting style. You like asteroids? How about them asteroids?

There’s a few hundred larger than 100 km across, and tens of millions of rocks a hundred meters across. Any one of these could ruin a good day, or bring a bad day to a welcome firey close for either a depressed wayfaring spacecraft or a little bluegreen speck of a planet. Which sounds dangerous all the way around.

Fortunately, our asteroid belt is a vast region of space. Let’s wind up the perspective-o-meter. If you divide the total number of objects in the field by the volume of space that asteroid belt takes up, each space rock is separated by hundreds of thousands of kilometers. Think of it as gravity’s remarkably spacious zen rock garden.

Ceres compared to asteroids visited to date, including Vesta, Dawn's mapping target in 2011. Image by NASA/ESA. Compiled by Paul Schenck. — Ceres compared to asteroids visited to date, including Vesta, Dawn’s mapping target in 2011. Image by NASA/ESA. Compiled by Paul Schenck.

As a result, when NASA engineers plot a spacecraft’s route through the asteroid belt, they don’t expect to make a close encounter with any asteroids – in fact, they’ll change its flight path to intercept asteroids en route. Because hey look, asteroid!

Even though Ceres was discovered in 1801, it’s never been observed up close, until now. NASA’s Dawn spacecraft already visited Asteroid Vesta, and by the time you’re watching this video, it will have captured close-up images of the surface of Ceres.

Once again, science fiction creatives sold us out to drama over hard science. If you’re passing through an asteroid belt, you won’t need to dodge and weave to avoid the space rocks. In fact, you probably wouldn’t even know you were passing through a belt at all. You’d have to go way the heck over there to even get a nearby look at one of the bloody things. So we’re safe, our speck is safe, and all the little spacecraft are safe…. for now.

Which dramatic version of “asteroids” are you most fond of? Tell us in the comments below.

March 30, 2015February 27, 2017 by Fraser Cain

Will the Universe Run Out Of Energy?

It seems like the good times will go on forever, so feel free to keep on wasting energy. But entropy is patient, and eventually, it’ll make sure there’s no usable energy left in the Universe.

Thanks to the donations of generations of dinosaurs and their plant buddies, we’ve got fossils to burn. If we ever get off our dependence on those kinds of fuels, we’ll take advantage of renewable resources, like solar, wind, tidal, smug and geothermal. And if the physicists really deliver the goods, we’ll harness the power of the Sun and generate a nigh unlimited amount of fusion energy using the abundant hydrogen in all the oceans of the world. Fire up that replicator, the raktajino is on the house. Also, everything is now made of diamonds.

We’ll never run out of H+. Heck that stuff is already cluttering up our daily experience. 75% of the baryonic mass of the Universe is our little one-protoned friend. Closely followed up by helium and lithium, which we’ll gladly burn in our futuristic fusion reactors. Make no mistake, it’s all goin’ in.

It looks like the good times will never end. If we’ve energy to burn, we’ll never be able to contain our urges. Escalating off into more bizarre uses. Kilimajaro-sized ocean cruise liners catering to our most indulgent fantasies, colossal megastructure orbital laser casinos where life is cheap in the arena of sport. We’ll build bigger boards and bigger nails.or something absolutely ridiculous and decadent like artificial ski-hills in Dubai. Sadly, it’s naive to think it’s forever. Someday, quietly, those good times will end. Not soon, but in the distant distant future, all energy in the Universe will have been spent, and there won’t a spare electron to power a single LED.

Astronomers have thought long and hard about the distant future of the Universe. Once the main sequence stars have used up their hydrogen and become cold white dwarfs and even the dimmest red dwarfs have burned off their hydrogen. When the galaxies themselves can no longer make stars. After all the matter in the Universe is absorbed by black holes, or has cooled to the background temperature of the Universe.

Combining observations done with ESO's Very Large Telescope and NASA's Chandra X-ray telescope, astronomers have uncovered the most powerful pair of jets ever seen from a stellar black hole. The black hole blows a huge bubble of hot gas, 1,000 light-years across or twice as large and tens of times more powerful than the other such microquasars. The stellar black hole belongs to a binary system as pictured in this artist's impression. Credit: ESO/L. Calçada — Artist’s impression of a Star feeding a black hole. Credit: ESO/L. Calçada

Black holes themselves will evaporate, disappearing slowly over the eons until they all become pure energy. Even the last proton of matter will decay into energy and dissipate. Well, maybe. Actually, physicists aren’t really sure about that yet. Free Nobel prize if you can prove it. Just saying.

And all this time, the Universe has been expanding, spreading matter and energy apart. The mysterious dark energy has been causing the expansion of the Universe to accelerate, pushing material apart until single photons will stretch across light years of distance. This is entropy, the tendency for energy to be evenly distributed. Once everything, and I do mean all things, are the same temperature you’ve hit maximum entropy, where no further work can be done.

This is known as the heat death of the Universe. The temperature of the entire Universe will be an infinitesimal fraction of a degree above Absolute Zero. Right above the place where no further energy can be extracted from an atom and no work can be done. Terrifyingly, our Universe will be out of usable energy.

Interestingly, there’ll still be the same amount it started with, but it’ll be evenly distributed across all places, everywhere. This won’t happen any time soon. It’ll take trillions of years before the last stars die, and an incomprehensible amount of time before black holes evaporate. We also don’t even know if protons will actually decay at all. But heat death is our inevitable future.

There’s a glimmer of good news. The entire Universe might drop down to a new energy state. If we wait long enough, the Universe might spontaneously generate a new version of itself through quantum fluctuations. So with an infinite amount of time, who knows what might happen?

Burn up those dirty dinosaurs while you can! Enjoy the light from the Sun, and the sweet whirring power from your counter-top Mr. Fusion reactor. Your distant descendants will be jealous of your wasteful use of energy, non-smothering climate and access to coffee and chocolate, as they huddle around the fading heat from the last black holes, hoping for a new universe to appear.

What’s the most extreme use of energy you can imagine? Tell us in the comments below.