Posted on by Fraser Cain

What’s Causing The Universe To Expand?

What's Causing The Universe To Expand?

We’ve all heard that the Universe is expanding, but why is it expanding? What’s the force pushing everything outwards?

If still you don’t know that we live in an expanding Universe, then I’m clearly not doing my job.

And so once more, with feeling… the Universe is expanding. But that certainly doesn’t answer all the questions that go along with the it.

Like what’s the Universe expanding into? Which we did in another video, which I’ll list at the end of this episode. You might also want to know why is the Universe expanding? What’s making this happen? Did it give up its gym membership? Did it sign up for the gallon of ice cream of the month club? Has it completely embraced the blerch?

Edwin Hubble, the astronomer made famous by being named after a space telescope, provided the definitive evidence that the Universe was expanding. Observing distant galaxies, he observed they were fleeing outwards, in fact he was able to come up with calculations to show just how fast they were moving away from us.

Or to be more precise, he was able to show how fast all the galaxies are moving away from each other. Which was your question! Just like a minute ago! See you’re just as smart as Hubble!

So up until about 15 years ago, the only answer was momentum. The idea was that the Universe received all the energy it needed for its expansion in the first few moments after the Big Bang.

Imagine the beginning of the Universe, BOOM, like an explosion from a gun. And all the rest of the expansion is the Universe coasting outwards. For the longest time, astronomers were trying to figure out what this momentum would mean for the future of the Universe.

Dark Energy
The Hubble Space Telescope image of the inner regions of the lensing cluster Abell 1689 that is 2.2 billion light?years away. Light from distant background galaxies is bent by the concentrated dark matter in the cluster (shown in the blue overlay) to produce the plethora of arcs and arclets that were in turn used to constrain dark energy. Image courtesy of NASA?ESA, Jullo (JPL), Natarajan (Yale), Kneib (LAM)

Would the mutual gravity of all the objects in the Universe cause it to slow to a halt at some point in the distant future, or maybe even collapse in on itself, leading to a Big Crunch? Or just clump up in piles and stay on the couch all summer because it’s maybe a little lazy and isn’t ready to start going back to the gym yet?

In 1999, astronomers discovered something completely unexpected… dark energy. As they were doing their observations to figure out exactly how the Universe would coast to a stop, they discovered that it’s actually speeding up. It’s as if that bullet is actually a rocket and it’s accelerating.

Now it appears that the Universe will not only expand forever, but the speed of its expansion will continue to accelerate faster and faster. So what’s causing this expansion? Currently, we believe it’s mostly momentum left over from the Big Bang, and the force of dark energy will be accelerating this expansion. Forever.

How do you feel about a rapidly accelerating expanding Universe? Tell us in the comments below.

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

Posted on by Fraser Cain

When Did the First Stars Form?

When Did the First Stars Form?

Shortly after the Big Bang, the Universe had cooled to the point that the first stars could form out of the primordial hydrogen. How long did it take, and what did these first stars like?

Hydrogen soup. Doesn’t that sound delicious? Perhaps not for humans, but certainly for the first stars!

Early in the Universe, in a spectacular show of stellar soupification, clouds of hydrogen atoms gathered together. They combined with one another. The collected mass got bigger and bigger, and after a time, ignition. The first stars were alive!

Well, alive in the sense that they were burning – not that they had feelings or knew what was going on, or had opinions, or were beginning to write would what would eventually become the first Onion article or anything.

But where did all that gas come from, and can we spot the evidence of those long-ago stars today? As you know, the Big Bang got our Universe off to a speedy start of expansion. It then took 400,000 years for us to see any light at all. Protons and electrons and other small particles were floating around, but it was far too hot for them to interact.

Once the power of the Big Bang finally faded, those protons and electrons paired up and created hydrogen. This is called, rather uninventively, “recombination”. I’d rather just call it hydrogen soup. We’ve got energy. But what is the secret ingredient that sparked these stars? It was just that soup clumping together over time.

A map of the faint microwave radiation left over after the big bang shows superclusters (red circles) and supervoids (blue circles). Credit: B. Granett, M. Neyrinck, I. Szapudi
A map of the faint microwave radiation left over after the big bang shows superclusters (red circles) and supervoids (blue circles). Credit: B. Granett, M. Neyrinck, I. Szapudi

We can’t say to the minute when the first stars formed, but we have a pretty good idea. The Wilkinson Microwave Anisotropy Probe, aka WMAP examined what happened when these clouds of hydrogen molecules got together, creating tiny temperature differences of only a millionth of a degree.

Over time, gravity began to yank matter from spots of lower density into the higher-density regions, making the clumps even bigger. Fantastically bigger. So big that about 200 million years after the clumps were formed, it was possible for these hydrogen molecules to ram into each other at very high speeds.

This process is called nuclear fusion. On Earth, it’s a way to produce energy. Same goes for a star. With enough nuclear reactions happening, the cloud of gas compresses and creates a glow. And these stars weren’t tiny – they were monsters! NASA says the first stars were 30 to 300 times as massive as the sun, shining millions of times brighter.

The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer, to show that a superdense neutron star is energizing the expanding Nebula by spewing out magnetic fields and a blizzard of extremely high-energy particles. The Chandra X-ray image is shown in light blue, the Hubble Space Telescope optical images are in green and dark blue, and the Spitzer Space Telescope’s infrared image is in red. The size of the X-ray image is smaller than the others because ultrahigh-energy X-ray emitting electrons radiate away their energy more quickly than the lower-energy electrons emitting optical and infrared light. The neutron star is the bright white dot in the center of the image.
The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer.

But this flashy behavior came at a price, because in only a few million years, the stars grew unstable and exploded into supernovae. These stars weren’t only exploding. They were also altering the soup around them. They were big emitters of ultraviolet light. It’s a very energetic wavelength, best known for causing skin cancer.

So, this UV light struck the hydrogen surrounding the stars. This split the atoms apart into electrons and protons again, leaving quite the mess in space. But it’s through this process that we can learn more about these earliest stars.The stars are long gone, but like a criminal fleeing the scene, they left a pile of evidence behind for their existence. Splitting these atoms was their evidence. This re-ionization is one key piece of understanding how these stars came to be.

So it was an action-packed time for the universe, with the Big Bang, then the emergence of soup and then the first stars. It’s quite an exciting start for our galactic history.

What do you think the first stars looked like?

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

Posted on by Fraser Cain

What Strange Places Are Habitable?

What Strange Places are Habitable
What Strange Places are Habitable

Everywhere we look on Earth, we find life. Even in the strangest corners of planet. What other places in the Universe might be habitable?

There’s life here on Earth, but what other places could there be life? This could be life that we might recognize, and maybe even life as we don’t understand it.

People always accuse me of being closed minded towards the search for life. Why do I always want there to be an energy source and liquid water? Why am I so hydrocentric? Scientists understand how life works here on Earth. Wherever we find liquid water, we find life: under glaciers, in your armpits, hydrothermal vents, in acidic water, up your nose, etc.

Water acts as a solvent, a place where atoms can be moved around and built into new structures by life forms. It makes sense to search for liquid water as it always seems to have life here. So where could we go searching for liquid water in the rest of the Universe?

Under the surface of Europa, there are deep oceans. They’re warmed by the gravitational interactions of Jupiter tidally flexing the surface of the moon. There could be life huddled around volcanic vents within its ocean. There’s a similar situation in Saturn’s Moon Enceladus, which is spewing out water ice into space; there might be vast reserves of liquid water underneath its surface. You could imagine a habitable moon orbiting a gas giant in another star system, or maybe you can just let George Lucas imagine it for you and fill it with Ewoks.

The white dwarf G29-38 (Image Credit: NASA)
The white dwarf G29-38 (Image Credit: NASA)

Let’s look further afield. What about dying white dwarf stars? Even though their main sequence days are over, they’re still giving off a lot of energy, and will slowly cool down over the coming billions of years. Brown dwarfs could get in on this action as well. Even though they never had enough mass to ignite solar fusion, they’re still generating heat. This could provide a safe warm place for planets to harbor life.

It gets a little trickier in either of these systems. White and brown dwarfs would have very narrow habitable zones, maybe 1/100th the size of the one in our Solar System. And it might shift too quickly for life to get started or survive for very long. This is our view, what we know life to be with water as a solvent. But astrobiologists have found other liquids that might work well as solvents too.

Artist concept of Methane-Ethane lakes on Titan (Credit: Copyright 2008 Karl Kofoed). Click for larger version.
Artist concept of Methane-Ethane lakes on Titan (Credit: Copyright 2008 Karl Kofoed). Click for larger version.

What about life forms that live in oceans of liquid methane on Titan, or creatures that use silicon or boron instead of carbon. It might just not be science fiction after all. It’s a vast Universe out there, stranger than we can imagine. Astronomers are looking for life wherever makes sense – wherever there’s liquid water. And if they don’t find any there, they’ll start looking places that don’t make sense.

What do you think? When we first find life, what will be its core building block? Silicon? Boron? or something even more exotic?

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

Posted on by Jason Major

No, This Is Not a Photo of India on Diwali

Yes, it's India, but it's not a photo captured from space during Diwali night. (Credit: NASA)

Diwali, the Indian festival of lights, falls on Thursday, Oct. 23 this year and with it come celebrations, gift-giving, and brilliant lighting and firework displays all across the subcontinent of India… but this isn’t a picture of that. What is it exactly? Find out below…

Over the past several years this image has repeatedly resurfaced online, especially around the time of Diwali. And understandably so: it’s a beautiful view of India seemingly decorated for the festival… one can easily imagine the entire country awash in colorful lights from shore to shore.

But it’s not a photo at all, or even a singular image. Rather it’s a composite of many images acquired from a USAF Defense Meteorological Satellite Program (DMSP) satellite over the course of several years, and assembled by NOAA scientist Chris Elvidge to show the country’s growing population and urban areas.

In a 2012 article by Robert Johnson on Business Insider a NASA spokesperson described the colors in the image: “The white lights were the only illumination visible before 1992. The blue lights appeared in 1992. The green lights in 1998. And the red lights appeared in 2003.”

So what does India look like at night during the five-day-long Diwali festival? Click here and see.

While city lighting in India is definitely visible from space, it’s not the rainbow explosion of neon colors that Internet hoaxers and uninformed online enthusiasts would eagerly have you believe. According to Adam Voiland on the NASA Earth Observatory site, “in reality, any extra light produced during Diwali is so subtle that it is likely imperceptible when observed from space.”

So this year, don’t fall for any false descriptions of this picture… and, Happy Diwali!

Sources: Business Insider, Mashable, NASA Earth Observatory, EarthSky. Read more about the 2014 celebration of Diwali here.

HT to Peter Caltner on Twitter for re-alerting me of this.

Posted on by Brian Koberlein

What Would A Black Hole Look Like?

Artistic view of a radiating black hole. Credit: NASA

If you could see a black hole with your own eyeballs, what would you see?

Here on the Guide to Space production team: We love everything about Black Holes.

We like how they’re terrifying and completely conflict with our day to day experience of how stuff should work. We like how they completely mess you up before absolutely tearing you pieces, and we like how they ruin time and space and everything nearby.

We like them so much, we even enjoy giving them cute nick names like “Kevin”.

So I’m now going to show you images and animations of black holes.
Should you find this either too exciting or terrifying and need a breather I suggest you pause the video and walk around the block and try not to think about how absolutely terrifying these things are.

Those are just the artist’s illustrations, who’ve no doubt been awe inspired in the same way the rest of us have… but those people have never ACTUALLY seen one. Have they?

Is that what a black hole would really look like? Or are these just pictures of lasercorns?
I’ve got good news!

Here’s a picture of a real black hole. Can’t see much? That’s because it’s more than 25,000 light years away. It’s got 4 million times the mass of the Sun, and it’s still a tiny dot.

So, how do we know it’s there? The answer is awful. Even if we can’t see them directly, they make such a giant mess of things in their neighborhood we can still figure out where they are.

For an actively feeding black hole, we see a disk of material surrounding it.

This artist’s impression shows the surroundings of the supermassive black hole at the heart of the active galaxy NGC 3783 in the southern constellation of Centaurus (The Centaur). Credit: ESO/M. Kornmesser
This artist’s impression shows the surroundings of the supermassive black hole at the heart of the active galaxy NGC 3783 in the southern constellation of Centaurus (The Centaur). Credit: ESO/M. Kornmesser

Quasars are the jets emanating from active black holes, and we see them billions of light-years away. As you get closer, this area would get brighter until it was like you were close to millions of stars. The radiation would be overwhelming. Closer and closer, there would be region of total darkness, that’s the black hole itself.

For non-active or “sleepy time” black holes, we’d only see the distortion of light around them as light is bent by gravity. As you got closer and closer, there’d be less light coming from the area around the black hole. No photons can be reflected by it. You’d then pass a region called the photon sphere, where light is orbiting the black hole. You’d see the whole Universe as a swirling jumble of mixed up photons.

Next the event horizon, where light can’t escape. You could look out into the Universe and see the distorted light coming from everywhere, but the singularity itself would still be dark. Is it a single point, or a sphere? Astronomers don’t know yet.

A new telescope is in the works called the Event Horizon Telescope. It would combine the light from a worldwide constellation of radio telescopes. They’re hoping to actually image the event horizon of a black hole, and could have their first images within 5 years. Hopefully it’ll never get loaded onto a ship with Sam Neill.

Here’s hoping we’re just a few years away from knowing what black holes look like directly. But once seen, they can never be unseen. What do you think it’ll look like? tell us in the comments below!

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

Posted on by Fraser Cain

What Does Earth Look Like From the Moon?

What Does Earth Look Like From the Moon?

If you could stand on the Moon and look back at the Earth, what would you see? How would it compare from our familiar vantage point?

We know what the Moon looks like from Earth, but what would the Earth look like from the Moon?

Pretty strange, actually.

The Moon is tidally locked to us, and it presents only one face to the Earth.

If you were on the near side of the Moon, the Earth would always be in the sky. And if you were on the far side, you’d never see it.

Also, it’s weird there. So you’d probably want to move.

If you were standing on the Moon, looking up, you’d see the Earth, hanging in the sky forever, or for however long your robot body holds out.

It would go through phases, like the Moon, moving from total darkness, though quarter illumination, Full Earth, and back again. But the features on the Earth would be changing. The face of the Earth would be illuminated, and you’d see the entire planet turning throughout the day and you could use it to cheat on Geography tests.

It wouldn’t be totally dark on the night side because “humans”. You’d see those beautiful blobs of stringy light on the shadowed parts of the Earth.

Our Moon follows an elliptical path around the Earth, getting as close as 363,000 km and as far as 405,000 km.

This means the Earth would get bigger and smaller in the sky. As Earth is much larger than the Moon, it would take up 13 times as much area.

The Earth wouldn’t actually hang motionless in the sky. We see lunar libration from our perspective, which lets us peek around the corner of the Moon. But from the Moon, we’d see the Earth move back and forth in the sky over 27 days.

Earthrise (credit—Apollo 8/NASA)
Earthrise (credit—Apollo 8/NASA)

Remember this famous Earthrise photo captured by Apollo 8? It’s on every single sales brochure for lunar real estate.

Don’t be fooled, if you were on the Moon, you’d never see an Earthrise like that.
In fact, the only way to get a view like that is be on a spacecraft orbiting the Moon.

If I lived on the Moon, I’d want property Earthside.

Would you like to see the Earth from the Moon? What other views of the Solar System would you like to get?

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

Posted on by Jason Major

Watch the “Blood Moon” Eclipse from Mercury

Earth and the Moon imaged by the MESSENGER spacecraft on Oct. 8, 2014

Yes, it’s another time-lapse of the October 8 lunar eclipse that was observed by skywatchers across half the Earth… except that these images weren’t captured from Earth at all; this was the view from Mercury!

The animation above was constructed from 31 images taken two minutes apart by the MESSENGER spacecraft between 5:18 a.m. and 6:18 a.m. EDT on Oct. 8, 2014.

“From Mercury, the Earth and Moon normally appear as if they were two very bright stars,” said Hari Nair, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory, which developed and operates the MESSENGER mission for NASA. “During a lunar eclipse, the Moon seems to disappear during its passage through the Earth’s shadow, as shown in the movie.”

According to Nair the images have been zoomed by a factor of two and the Moon’s brightness has been increased by a factor of about 25 to enhance visibility. Captured by MESSENGER’s narrow-angle camera, Earth and the Moon were 0.713 AU (106.6 million km / 66.2 million miles) away from Mercury when the images were acquired.

Want to see some great photos of the eclipse shared by talented photographers around the world? Click here.

The Oct. 8 “Hunter’s Moon” eclipse was the second and last total lunar eclipse of 2014. The next will occur on April 4 of next year… but by that time MESSENGER won’t be around to witness it.

Launched August 3, 2004, MESSENGER entered orbit at Mercury on March 18, 2011. It is currently nearing the end of its missions as well as its its operational life, but we still have several more months of observations to look forward to from around the Solar System’s innermost planet before MESSENGER makes its final pass and ultimately impacts Mercury’s surface in March 2015.

Video credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Source: MESSENGER news release