Posted on by Fraser Cain

Is the Universe Dying?

Is the Universe Dying?

Is our 13.8 billion year old universe actually in its death throes?

Poor Universe, its demise announced right in it’s prime. At only 13.8 billion years old, when you peer across the multiverse it’s barely middle age. And yet, it sadly dwindles here in hospice.

Is it a Galactus infestation? The Unicronabetes? Time to let go, move on and find a new Universe, because this one is all but dead and gone and but a shell of its former self.

The news of imminent demise was recently broadcast in mid 2015. Based on research looking at the light coming from over 200,000 galaxies, they found that the galaxies are putting out half as much light as they were 2 billion years ago. So if our math is right, less light equals more death.

So tell it to me straight, Doctor Spaceman(SPAH-CHEM-AN), how long have we got? Astronomers have known for a long time that the Universe was much more active in the distant past, when everything was closer and denser, and better. Back then, more of it was the primordial hydrogen left over from the Big Bang, supplying galaxies for star formation. Currently, there are only 1 to 3 new stars formed in the Milky Way every year. Which is pretty slow by Milky Way standards.

Not even at the busiest time of star formation, our Sun formed 5 billion years ago. 5 billion years before that, just a short 4 billion after the Big Bang, star formation peaked out. There were 30 times more stars forming then, than we see today.

When stars were formed actually makes a difference. For example, the fact that it took so long for our Sun to form is a good thing. The heavier elements in the Solar System, really anything higher up the periodic table from hydrogen and helium, had to be formed inside other stars. Main sequence stars like our own Sun spew out heavier elements from their solar winds, while supernovae created the heaviest elements in a moment of catastrophic collapse. Astronomers are pretty sure we needed a few generations of stars to build up enough of the heavier elements that life depends on, and probably wouldn’t be here without it.

Even if life did form here on Earth billions of years ago, when the Universe was really cranking, it would wish it was never born. With 30 times as much star formation going on, there would be intense radiation blasting away from all these newly forming stars and their subsequent supernovae detonations. So be glad life formed when it did. Sometimes a little quiet is better.

So, how long has the Universe got? It appears that it’s not going to crash together in the future, it’s just going to keep on expanding, and expanding, forever and ever.

Our eyes would never see the Crab Nebula as this Hubble image shows it. Image credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)
Our eyes would never see the Crab Nebula as this Hubble image shows it. Image credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)

In a few billion years, star formation will be a fraction of what it is today. In a few trillion, only the longest lived, lowest mass red dwarfs will still be pushing out their feeble light. Then, one by one, galaxies will see their last star flicker and fade away into the darkness. Then there’ll only be dead stars and dead planets, cooling down to the background temperature of the Universe as their galaxies accelerate from one another into the expanding void.

Eventually everything will be black holes, or milling about waiting to be trapped in black holes. And these black holes themselves will take an incomprehensible mighty pile of years to evaporate away to nothing.

So yes, our Universe is dying. Just like in a cheery Sartre play, it started dying the moment it began its existence. According to astronomers, the Universe will never truly die. It’ll just reach a distant future when there’s so little usable energy, it’ll be mostly dead. Dead enough? Dead inside.

As Miracle Max knows, mostly dead is still slightly alive. Who knows what future civilizations will figure out in the googol years between then and now.

Too sad? Let’s wildly speculate on futuristic technologies advanced civilizations will use to outlast the heat death of the Universe or flat out cheat death and re-spark it into a whole new cycle of Universal renewal.

Posted on by Jason Major

This is a Scale Model of the Solar System Like You’ve Never Seen Before

Five friends traveled to a dry lake bed in Nevada to create an accurate scale model of the planets' orbits. (Screenshot) © Wylie Overstreet and Alex Gorosh

We’ve all seen illustrations of the Solar System. They’re in our school textbooks, on posters, on websites, on t-shirts… in some cases they’re used to represent the word “science” itself (and for good reason.) But, for the most part, they’re all wrong. At least where scale is concerned.

Sure, you can show the Sun and planets in relative size to each other accurately. But then the actual distances between them will probably be way off.* And OK, you can outline the planets’ concentric orbits around the Sun to scale pretty easily. But then there’s no convenient way to make sure that the planets themselves would actually be visible. In order to achieve both, you have to leave the realm of convenience behind entirely and make a physical model that, were you to start with an Earth the size of a marble, would stretch for several miles (and that’s not even taking Pluto into consideration.)

This is exactly what filmmaker Wylie Overstreet and four of his friends did in 2014, spending a day and a half on a dry lake bed in Nevada where they measured out and set up a scale model of the Sun and planets (not including Pluto, don’t tell Alan Stern) including their respective circular orbits. They then shot time-lapse images of their illuminated cars driving around the orbits. The resulting video is educational, mesmerizing, beautiful, and overall a wonderful demonstration of the staggering scale of space in the Solar System.

Watch the video below:

Or watch full-screen on Vimeo here.

For some reason whenever I think about the sheer amount of space there actually is in space, it gets me a like choked up. These guys get an “A+” for effort, execution, and entertainment!

Credit: Wylie Overstreet and Alex Gorosh

*There have been a few web pages that have been able to show the scale sizes and distances of the planets (and there are even some driving-distance ones too) but often they oversimplify by lining the planets up in a row — which doesn’t happen all that often and doesn’t portray the orbital circumferences either. This all just happens to be a favorite contemplating point of mine.

Posted on by Fraser Cain

Could We Terraform a Black Hole?

Could We Terraform a Black Hole?

Is there any possible way to take a black hole and terraform it to be a place we could actually live?

In the challenge of terraforming the Sun, we all learned that outside of buying a Dyson Spaceshell 2000 made out of a solar system’s worth of planetbutter, it’s a terrible idea.

Making a star into a habitable world, means first destroying the stellar furnace. Which isn’t good for anyone, “Hey, free energy! vs. Let’s wreck this thing and build houses!”

Doubling down on this idea, a group of brilliant Guidensians wanted to crank the absurdity knob all the way up. You wanted to know if it would be possible to terraform a black hole.

In order to terraform something, we convert it from being Britney Spears’ level of toxic into something that humans can comfortably live on. We want reasonable temperatures, breathable atmosphere, low levels of radiation, and Earthish gravity.

With temperatures inversely proportional to their mass, a solar mass black hole is about 60 billionths of a Kelvin. This is just a smidge over absolute zero. Otherwise known as “pretty damn” cold. Actively feeding black holes can be surrounded by an accretion disk of material that’s more than 10 million degrees Kelvin, which would also kill you. Make a note, fix the temperature.

There’s no atmosphere, and it’s either the empty vacuum of space, or the superheated plasma surrounding an actively feeding black hole. Can you breathe plasma? If the answer is yes, this could work for you. If not, we’ll need to fix that.

You’d be hard pressed to find a more lethal radiation source in the entire Universe.

Black holes can spin at close to the speed of light, generating massive magnetic fields. These magnetic fields whip high energy particles around them, creating lethal doses of radiation. There are high energy particle jets pouring out of some supermassive black holes, moving at nearly the speed of light. You don’t want any part of that. We’ll add that to the list.

Black holes are known for being an excellent source of vitamin gravity. Out in orbit, it’s not so bad. Replace our Sun with a black hole of the same mass, and you wouldn’t be able to tell the difference.

So, problem solved? Not quite. If you tried to walk on the surface, you’d get shredded into a one-atom juicy stream of extruded tubemanity before you got anywhere near the time traveling alien library at the caramel center.

Reduce the gravity. Got it.

Artist rendering of a supermassive black hole. Credit: NASA / JPL-Caltech.
Artist rendering of a supermassive black hole. Credit: NASA / JPL-Caltech.

As we learned in a previous episode on how to kill black holes, there’s nothing you can do to affect them. You couldn’t smash comets into it to give it an atmosphere, it would just turn them into more black hole. You couldn’t fire a laser to extract material and reduce the mass, it would just turn your puny laser into more black hole.

Antimatter, explosives, stars, rocks, paper, scissors…black hole beats them all.

Repeat after me. “Om, nom, nom”.

All we can do is wait for it to evaporate over incomprehensible lengths of time. There are a few snags with this strategy, such as it will remain as a black hole until the last two particles evaporate away. There’s no point where it would magically become a regular planetoid.

That’s a full list of renovations for the cast and crew of “Pimp my Black Hole”.

Let’s look at our options. You can move it, just like we can move the Earth. Throw stuff really close to a black hole, and you get it moving with gravity. You could make it spin faster by dropping stuff into it, right up until it’s rotating at the edge of the speed of light, and you can make it more massive.

With that as our set of tools, there’s no way we’re ever going to live on a black hole.

It could be possible to surround a black hole with a Dyson Sphere, like a star.

Freemon Dyson theorized that eventually, a civilization would be able to build a megastructure around its star to capture all its energy. Credit: SentientDevelopments.com
Freemon Dyson theorized that eventually, a civilization would be able to build a megastructure around its star to capture all its energy. Credit: SentientDevelopments.com

It turns out there’s a way to have a pet black hole pay dividends aside from eating all your table scraps, shameful magazines and radioactive waste. By dropping matter into a black hole that’s spinning at close to the speed of light, you can actually extract energy from it.

Imagine you had an asteroid that was formed by two large rocks. As they get closer and closer to the black hole, tidal forces tear them apart. One chunk falls into the black hole, the smaller remaining rock has less collective mass, which allows it to escape. This remaining rock steals rotational energy from the black hole, which then slows down the rotation just a little bit.

This is the Penrose Process, named after the physicist who developed the idea. Astronomers calculated you can extract 20% of pure energy from matter that you drop in.

There’s isn’t much out there that would give you better return on your investment.

Also, it’s got to have a similar satisfying feeling as dropping pebbles off a bridge and watching them disappear from existence.

Terraforming a black hole is a terrible idea that will totally get us all killed. Don’t do it.

If you have to get close to that freakish hellscape I do recommend surrounding your pet with a Dyson Sphere and then feeding it matter and enjoying the energy you get in return.

A futuristic energy hungry civilization bent on evil couldn’t hope for a better place to live.

Have you got any more questions about black holes? Give us your suggestions in the comments below.

Posted on by Fraser Cain

What Do Other Planets Sound Like?

What Do Other Planets Sound Like?

We know that in space, no one can hear you scream. But what would things sound like on another planet?

When humans finally set foot on Mars, they’re going to be curious about everything around them.

What’s under that rock? What does it feel like to jump in the lower Martian gravity. What does Martian regolith taste like? What’s the bitcoin to red rock exchange rate?

As long as they perform their activities in the safety of a pressurized habitation module or exosuit, everything should be fine. But what does Mars sound like?

I urge all future Martian travelers, no matter how badly you want to know the answer to this question: don’t take your helmet off. With only 1% the atmospheric pressure of Earth, you’d empty your lungs with a final scream in a brief and foolish moment, then suffocate horribly with a mouthful of dust on the surface of the Red Planet.

But… actually, even the screaming would sound a little different. How different? Let me show you. First you just need to take your helmet off for a just a little sec, just an itsy bitsy second. Here, I’ll hold it for you. Oh, come on, just take your helmet off. All the cool kids are doing it.

What about Venus? Or Titan? What would everything sound like on an alien world?

We evolved to exist on Earth, and so it’s perfectly safe for us to listen to sounds in the air. No space suit needed. Unless you didn’t evolve on Earth, in which case I offer to serve as emissary to our all new alien overlords.

You know sounds travel when waves of energy propagate through a medium, like air or water. The molecules bump into each other and pass along the energy until they strike something that won’t move, like your ear drum. Then your brain turns bouncing into sounds.

The speed of the waves depends on what the medium is made of and how dense it is. For example, sound travels at about 340 meters/second in dry air, at sea level at room temperature. Sound moves much more quickly through liquid. In water it’s nearly 1,500 m/s. It’s even faster through a solid – iron is up past 5,100 m/s. Our brain perceives a different sound depending on the intensity of the waves and how quickly they bounce off our ears.

Artist's impression of the surface of Venus. Credit: ESA/AOES
Artist’s impression of the surface of Venus. Credit: ESA/AOES

Other worlds have media that sound waves can travel through, and with your eardrum exposed to the atmosphere you should theoretically hear sounds on other worlds. Catastrophic biological failures from using your eardrums outside of documented pressure tolerances notwithstanding.

Professor Tim Leighton and a team of researchers from the University of Southampton have simulated what we would hear standing on the surface of other worlds, like Mars, Venus or even Saturn’s Moon Titan.

On Venus, the pitch of your voice would become deeper, because vocal cords would vibrate much more slowly in the thicker Venusian atmosphere. But sounds would travel more quickly through the soupy atmosphere. According to Dr. Leighton, humans would sound like bass Smurfs. Mars would sound a little bit higher, and Titan would sound totally alien.

Dr. Leighton actually simulated the same sound on different worlds. Here’s the sound of thunder on Earth.
Here’s what it would sound like on Venus.
And here’s what it would sound like on Mars.
Here’s what a probe splashing into water on Earth would sound like.
And here’s what it would sound like splashing into a hydrocarbon lake on Titan.

You might be amazed to learn that we still haven’t actually recorded sounds on another world, right up until someone points out that putting a microphone on another planet hasn’t been that big a priority for any space mission.

A fish-eye view of Titan's surface from the European Space Agency's Huygens lander in January 2005. Credit: ESA/NASA/JPL/University of Arizona
A fish-eye view of Titan’s surface from the European Space Agency’s Huygens lander in January 2005. Credit: ESA/NASA/JPL/University of Arizona

Especially when we could analyze soil samples, but hey fart sounds played and then recorded in the Venusian atmosphere could prove incredibly valuable to the future of internet soundboards.

The Planetary Society has been working to get a microphone included on a mission. They actually included a microphone on the Mars Polar Lander mission that failed in 1999. Another French mission was going to have a microphone, but it was cancelled. There are no microphones on either Spirit or Opportunity, and the Curiosity Rover doesn’t have one either despite its totally bumping stereo.

Here’s is the only thing we’ve got. When NASA’s Phoenix Lander reached the Red Planet in 2008, it had a microphone on board to capture sounds. It recorded audio as it entered the atmosphere, but operators turned the instrument off before it reached the surface because they were worried it would interfere with the landing.

Mars Phoenix Lander. Image credit: NASA/JPL/SSI

Here’s the recording.

Meh. I’m going to need you to do better NASA. I want an actual microphone recording winds on the surface of Mars. I hope it’s something Dethklok puts on their next album, they could afford that kind of expense.

It turns out, that if you travel to an alien world, not only would the sights be different, but the sounds would be alien too. Of course, you’d never know because you’re be too chicken to take your helmet off and take in the sounds through the superheated carbon dioxide or methane atmosphere.

What sounds would you like to hear on an alien world? Tell us in the comments below.

Posted on by Fraser Cain

What About a Mission to Europa?

What About a Mission to Europa?

Europa’s water exists in a layer around the planet, encased in a layer of ice. Could there be life down there?

Hooray! Welcome to the 200th official episode of the Guide To Space!

First off, thank you. Thank you for watching, liking, sharing, subscribing and being a patron of our show. Yes, you. Thank you.

So to celebrate, a few weeks ago we invited the members of the Weekly Space Hangout Crew Google+ Community to suggest topics for episodes, and the winner would receive a precious iron-nickel meteorite. Congratulations Andres Munoz, this meteorite is for you.

This episode, chosen by Andres, is for everyone.

The search for life in the Solar System is about the hunt for water. Wherever we find liquid water on Earth, we find life. I’m talking everywhere. In the most briny, salty pools in Antarctica, in the hottest hot springs in Yellowstone, under glaciers, and kilometers deep underground.

So we go searching for liquid water in the Solar System.

You might be surprised to learn that Jupiter’s moon Europa has the most water in the entire Solar System. If you took all the water on Earth, collected it into a big sphere, it would measure almost 1,400 kilometers across.

Europa’s water would measure nearly 1,800 kilometers.All that water exists in a layer around Europa, encased in a layer of ice. How thick? We don’t know.

Is there life down there? We don’t know.You can say there might be, and it wouldn’t be untrue. However, if you say there isn’t, that’s way less interesting for clickbait purposes. Whenever we don’t know the answers to fundamental and intriguing questions like that, it’s time to send a mission.

Good news! An actual mission to Europa is in the works right now. In 2015, NASA approved the development of an orbiter mission to Europa. If all goes well, and nothing gets cancelled…

And nothing will get cancelled, right? Right? I heard Firefly. Which one of you said Firefly?!?

According to the plan, a spacecraft will launch in the 2020s, carrying 9 instruments to Europa. Most will be familiar cameras, mass spectrometers, and the like, to study the surface of Europa to a high level of resolution. Over the course of 45 flybys, the spacecraft will get down as close as 25 kilometers and capture it with incredible resolution.

A "colorized" image of Europa from NASA's Galileo spacecraft, whose mission ended in 2003. The whiteish areas are believed to be pure water ice. Credit: NASA/JPL-Caltech/SETI Institute
A “colorized” image of Europa from NASA’s Galileo spacecraft, whose mission ended in 2003. The whiteish areas are believed to be pure water ice. Credit: NASA/JPL-Caltech/SETI Institute

Perhaps the most exciting, and controversial instrument on board the new Europa Orbiter mission will be its ice-penetrating radar. Mission planners battled over installing a radar this sophisticated, as it will be an enormous drain on the orbiter’s power.

This for us is incredibly exciting. It will allow the spacecraft to map out the depth and thickness of Europa’s icy exterior. Is it thick or thin? Are there pockets of water trapped just below the surface, or is it tough shell that goes on for dozens of kilometers?

The worst case scenario is that the shell goes thicker than the radar can reach, and we won’t even know how far it goes.

Whatever happens, the Europa orbiter will be a boon to science, answer outstanding questions about the moon and the chances of finding life there.

We’re just getting started. What we really want to send is a lander. Because of the intense radiation from Jupiter, the Sun, and space itself, the surface of the ice on Europa would be sterilized. But dig down a few centimeters and you might find life that’s protected from the radiation.

A future Europa lander might be equipped with a heated drill attached to a tether. The lander would be have with a heat-generated radioisotope thermoelectric generator, like most of NASA’s big, outer Solar System spacecraft.

Artist illustration of a Europa probe. Image credit: NASA/JPL
Artist illustration of a Europa probe. Image credit: NASA/JPL

But in addition to using it for electricity, it’ll use the raw heat to help a tethered drill to grind through the ice a few meters and sample what’s down there.

Drilling more than a few meters is probably the stuff of science fiction. Russian scientists in Antarctica drilled for almost two decades to get through 4,000 meters of ice above Lake Vostok. Imagine trying to get through 100 kilometers of the stuff, on a distant world, with a robot.

But, since I’ve talked about moving the Sun, and terraforming the Moon, maybe I shouldn’t put any bounds on my imagination. Nuclear-powered Europa submarines will get us swimming with the singing Europan space whales in no time.

Europa is the best place to search the Solar System for life, and I’m excited to see what the upcoming Europa Orbiter mission turns up. And I’m even more excited about the possibility of any future lander missions.

It was a lot of fun wrapping my brain around a topic chosen by the fans. What topic would you like us to cover next? I’ve got a whole pocket of meteorites here. Put it in the comments below.

First, I want to thank everyone. It’s been a crazy race getting up to 200 episodes, but it’s been a blast all the way through. Thanks again for all your support and here’s to 200 more!

Posted on by Fraser Cain

Would We See the Aliens Coming?

Would We See the Aliens Coming?

If aliens were heading towards the Earth, would we see them coming?

Classic sci fi trope time. The air force detects a fleet of alien spacecraft out past Jupiter, leaving enough time to panic and demonstrate what awful monsters we truly are before they come ring our bell.
Is that how this would work?

Imagine a pivotal scene in your favorite alien mega disaster movie. Like the one where the gigantic alien ships appear over London, Washington, Tokyo, and Paris and shoots its light-explody ray, obliterating a montage of iconic buildings. Demonstrating how our landmark construction technology is nothing against their superior firepower.

What could we do? We’re merely meat muppets with pitiful silicon based technology. How could we ever hope to detect these aliens with their stealth spacecraft and 3rd stage guild navigators? If we’re going to do this, I’m going to make up some rules. If you don’t like my rules, go get your own show and then you can have your own rules.

Alternately, as some of you are clearly aware, you can rail against the Guide To Space in the comments below. Dune reference notwithstanding, I’m going to assume that aliens live in our Universe and obey the laws of physics as we understand them. And I know you’re going to say, what if they use physics we haven’t discovered yet?

Then just pause this video and get that out of your system. You can make that your first decree against the state right in the comments below. As I was saying, physical aliens, physical universe. We’ll discuss the metaphysical aliens in a magic universe in a future video. The ones that have crystals and can heal your liver through the power of song.

A basic rule of the Universe is that you can’t go faster than the speed of light. So I’m going to have any aliens trying to attack us traveling at sublight speeds.

So, we’ll say they’ve got access to a giant mountain of power. They can afford to travel at 10% the speed of light, which means before they get to us, they have to slow down. At this speed, deceleration is expensive. We’d see the energy signature from their brakes long before they even reached Earth.

Let’s say they’re passing the orbit of the dwarf planet Pluto, which is 4 light-hours away. Since they’re travelling at 10% the speed of light, we’d have about 40 hours to scramble jet fighters, get those tanks out onto the streets and round up Will Smith, Jeff Goldblum and Bruce Willis to hide behind.

A composite image with Chandra data (purple) showing a "point-like source" beside the remains of a supernova, suggesting a companion star may have survived the explosion. Credit: X-ray: NASA/CXC/SAO/F.Seward et al; Optical: NOAO/CTIO/MCELS, DSS
A composite image with Chandra data (purple) showing a “point-like source” beside the remains of a supernova, suggesting a companion star may have survived the explosion. Credit: X-ray: NASA/CXC/SAO/F.Seward et al; Optical: NOAO/CTIO/MCELS, DSS

Would we even notice? Maybe, or maybe not. A growing trend in astronomy is scanning the sky on a regular basis, looking for changes. Changes like supernova explosions, asteroids and comets zipping past, and pulsating variable stars.

One of the most exciting new observatories under construction is the Large Synoptic Survey Telescope in Chile. Once it begins regular operations in 2022, this array of telescopes will photograph the entire sky in fairly high resolution every few nights.

Computers will process the torrent of data coming from the observatory and search for anything that changes. What if they engage their cloak?

Actually (push glasses up your nose) the laws of physics say that the aliens can’t hide the waste heat from whatever space drive they’re using. We’re actually pretty good at detecting heat with our infrared telescopes.

A space drive decelerating a city-sized alien spacecraft from a significant portion of the speed of light would shed a mountain of heat, and that’s all heat we might detect.

Astronomers have been searching for alien civilizations by looking for waste heat generated by Dyson spheres encapsulating entire stars or even all the stars in a galaxy. Nothing’s turned up yet. Which I for one, find a little suspicious.

Freemon Dyson theorized that eventually, a civilization would be able to build a megastructure around its star to capture all its energy. Credit: SentientDevelopments.com
Freemon Dyson theorized that eventually, a civilization would be able to build a megastructure around its star to capture all its energy. Credit: SentientDevelopments.com

If you’re from an alien race who’s planning to invade. Cover your ears. If aliens wanted to catch us off guard, they can use one of the oldest tricks in the aerial combat book, known as the Dicta Boelcke. They can fly at us using the Sun as camouflage. A rather large portion of the sky is completely obscured by that glowing ball of fiery plasma. It worked in WW1, and it’ll still work now.

Okay, aliens you can listen in again. Everyone else might want to mute the next part, as it’s not terribly reassuring. Astronomers often discover asteroids skimming by the Earth just after they’ve just gone past. That’s because they hurl at us from the Sun, just like clever aliens.

To spot those asteroids, we’ll need to deploy a space-based sky survey that can watch the heavens from a different perspective than Earth. Plans for this kind of mission are actually in the works.

Even with our rudimentary technology, we’d actually stand a pretty good chance of noticing the alien attack vessels before they actually arrived at centre of Sector 001. It’ll get better with automated observatories and space-based sky surveys.

Of course, there’s little we can do if we did know the aliens were coming. We’d be best to start with some kind of deterrent, contaminate all our fresh water, load our livestock up on antibiotics and cover our cities in toxic smog to deter the harvesting of our citizens.

Do you think we’d stand a chance against an alien invasion? Tell us how we’d do in the comments below.

Posted on by Fraser Cain

What Was Here Before the Solar System?

What Was Here Before the Solar System?

The Solar System is 4.5 billion years old, but the Universe is much older. What was here before our Solar System formed?

The Solar System is old. Like, dial-up-fax-machine-old. 4.6 billion years to be specific. The Solar System has nothing on the Universe. It’s been around for 13.8 billion years, give or take a few hundred million. That means the Universe is three times older than the Solar System.

Astronomers think the Milky Way, is about 13.2 billion years old; almost as old as the Universe itself. It formed when smaller dwarf galaxies merged together to create the grand spiral we know today. It turns out the Milky Way has about 8.6 billion years of unaccounted time. Billions and billions of years to get up to all kinds of mischief before the Solar System showed up to keep an eye on things.

Our Galaxy takes 220 million years to rotate, so it’s done this about 60 times in total. As it turns, it swirls and mixes material together like a giant space blender. Clouds of gas and dust come together into vast star forming regions, massive stars have gone supernova, and then the clusters themselves have been torn up again, churning the stars into the Milky Way. This happens in the galaxy’s spiral arms, where the areas of higher density lead to regions of star formation.

So let’s go back, more than 4.6 billion years, before there was an Earth, a Sun, or even a Solar System. Our entire region was gas and dust, probably within one of the spiral arms. Want to know what it looked like? Some of your favorite pictures from the Hubble Space Telescope should help.

Here’s the Orion, Eagle, and the Tarantula Nebulae. These are star forming regions. They’re clouds of hydrogen left over from Big Bang, with dust expended by aging stars, and seeded with heavier elements formed by supernovae.

Astrophoto: The Orion Nebula by Vasco Soeiro
The Orion Nebula. Image Credit: Vasco Soeiro

After a few million years, regions of higher density began forming into stars, both large and small. Let’s take a look at a star-forming nebula again. See the dark knots? Those are newly forming stars surrounded by gas and dust in the stellar nursery.

You’re seeing many many stars, some are enormous monsters, others are more like our Sun, and some smaller red dwarfs. Most will eventually have planets surrounding them – and maybe, eventually life? If this was the environment, where are all those other stars?

Why do I feel so alone? Where are all our brothers and sisters? Where’s all the other stuff that’s in that picture? Where’s all my stuff?

TRAPPIST First Light Image of the Tarantula Nebula. Credit: ESO
TRAPPIST First Light Image of the Tarantula Nebula. Credit: ESO

Apparently nature hates a messy room and a cozy stellar nest. The nebula that made the Sun was either absorbed into the stars, or blown away by the powerful stellar winds from the largest stars. Eventually they cleared out the nebula, like a fans blowing out a smoky room.

At the earliest point, our solar nebula looked like the Eagle Nebula, after millions of years, it was more like the Pleiades Star Cluster, with bright stars surrounded by hazy nebulosity. It was the gravitational forces of the Milky Way which tore the members of our solar nursery into a structure like the Hyades Cluster. Finally, gravitational interactions tore our cluster apart, so our sibling stars were lost forever in the churning arms of the Milky Way.

We’ll never know exactly what was here before the Solar System; that evidence has long been blown away into space. But we can see other places in the Milky Way that give us a rough idea of what it might have looked like at various stages in its evolution.

What should we call our original star forming nebula? Give our own nebula a name in the comments below.

Posted on by Jason Major

Rosetta’s View of a Comet’s “Great Divide”

A shadowed cliff on comet 67P/C-G imaged by Rosetta in Oct. 2014 (Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0)

The latest image to be revealed of comet 67P/Churyumov-Gerasimenko comes from October 27, 2014, before the Philae lander even departed for its surface. Above we get a view of a dramatically-shadowed cliff separating two regions on 67P, the high, smooth plateaus of Babi and the boulder-strewn, slumped valley of Aten. Both are located on the larger lobe of the comet, while parts of the Ma’at region on the smaller “head” lobe can be seen in the distance at upper left. (You can see a regional map of comet 67P here.)

The image scale is about 75 cm (2.4 feet) per pixel and the entire image spans 770 meters across – about half a mile. Based on that, the cliff is easily over 190 meters (630 feet) high!

Here's a diagram of the image above in context with the entire comet. (ESA)
Here’s a diagram of the image above in context with the entire comet. (ESA)

It’s thought that the morphological differences in the Babi and Aten regions – in both texture and altitude – are the result of a massive loss of material from Aten at some point in the comet’s history. According to the entry on the Rosetta blog, the entire volume of the Aten “scoop” is equivalent to about 50 Great Pyramids of Giza… a fitting analogy considering the choice to name features on 67P with an ancient Egyptian theme.

See Comet 67P’s Enormous “Cheops” Boulder

The image above is one of a slew of NavCam images that will be released at the end of the month on ESA’s Archive Browser, captured by Rosetta after establishing orbit around 67P.

Source: ESA’s Rosetta blog

NavCam image of 67P/C-G acquired on May 12, 2015. The elongated depression at the center of the illuminated region is Aten. ( ESA/Rosetta/NavCam – CC BY-SA IGO 3.0)
NavCam image of 67P/C-G acquired on May 12, 2015. The elongated depression at the center of the illuminated region is Aten. ( ESA/Rosetta/NavCam – CC BY-SA IGO 3.0)