Guide to Space Archives

September 30, 2013December 23, 2015 by Fraser Cain

How Long Will Life Survive on Earth?

A powerful X-class solar flare erupting on the sun on July 6, 2012 photographed by the Solar Dynamics Observers. Credit: NASA

Life has existed on Earth for billions of years, appearing shortly after the planet had cooled and liquid water became available.

From the first bacteria to the amazingly complex animals we see today, life has colonized every corner of our planet.

As you know, our Sun has a limited lifespan.

Over the next 5 billion years, it will burn the last of its hydrogen, bloat up as a red giant and consume Mercury and Venus.

This would be totally disastrous for local flora and fauna, but all life on the surface of the Earth will already be long gone.

In fact, we have less than a billion years to enjoy the surface of our planet before it becomes inhospitable.

Because our Sun… is heating up.

You can’t feel it over the course of a human lifetime, but over hundreds of millions of years, the amount of radiation pouring out of the Sun will grow.

This will heat the surface of our planet to the point that the oceans boil.

At the core of the Sun, the high temperatures and pressures convert hydrogen into helium. For every tonne of material the Sun converts, it shrinks a bit making the Sun denser, and a little hotter.

Over the course of the next billion years or so, the amount of energy the Earth receives from the Sun will increase by about 10%. Which doesn’t sound like much, but it means a greenhouse effect of epic proportions.

A TerraSAR-X stripmap image from 23 April 2009. The larger icebergs are bright, while smaller icebergs are capsized and appear as dark blocks. The inset shows two superimposed Envisat ASAR images from 24 and 27 April. The region outlined in red indicates the area of the TerraSAR-X image. Credits: DLR, ESA (Annotations by A. Humbert, Münster University — A TerraSAR-X stripmap image of icebergs.

Whatever is left of the ice caps will melt, and the water itself will boil away, leaving the planet dry and parched. Water vapor is a powerful greenhouse gas, this will drive the temperatures even hotter.

Plate tectonics will shut down, and all the carbon will be stripped from the atmosphere.

It’ll be bad.

As temperatures rise, complex lifeforms will find life on Earth less hospitable. It will seem as if evolution is running in reverse, as plants and animals die off, leaving the invertebrates and eventually just microbial life.

This rise in temperature will be the end of life on the surface of Earth as we know it.

Still, there are reserves of water deep underground which will continue to protect microbial life for billions of years.

Perhaps they’ll experience that final baking when the Sun does reach the end of its life.

Even a few hundred million years is an incomprehensible amount of time compared to the age of our civilization.

If humanity does survive well into the future, is there anything we could do about this problem?

As the Sun heats up, making Earth inhospitable, it heats up the rest of the Solar System too. Frozen worlds in the Solar System will melt, becoming more habitable.

Encaladus, a moon of Saturn, as shown in this Voyager 1 image. Credit: NASA

It’s possible that future civilizations could relocate to the asteroid belt, or the moons of Saturn. We could try something even more radical: move the Earth.

By carefully steering asteroids so they barely miss us, an advanced civilization could distort the Earth’s orbit, relocating our planet further from the Sun.

As the Sun heats up, our planet would be continuously repositioned so the surface temperature stays roughly the same. Of course, this would be tricky business. Make the wrong move, and you’re facing the frigid cold of the outer Solar System.

So there’s no need to panic. Life here has a few hundred million years left; a billion, tops. But if we want to continue on for billions of years, we’ll want to add solar heating to our growing list of big problems.

September 27, 2013March 16, 2017 by Fraser Cain

How Do Black Holes Form?

Black holes are the most exotic and awe inspiring objects in the Universe.

Take the mass of an entire star. Compress it down into an object so compact that the force of gravity defies comprehension.

Nothing, not even light, can escape the pull of gravity from a black hole.

The idea was first conceived in the 18th century by the geologist John Mitchell. He realized that if you could compress the Sun down by several orders of magnitude, it would have gravity so strong that you’d need to be going faster than the speed of light to escape it.

Initially, black holes were considered nothing more than abstract mathematical concepts; even Einsten assumed they didn’t actually exist. But in 1931, the astronomer Chandrasekhar calculated that certain high mass stars might be able to collapse into black holes after all.

They turned out to be real, and over the next few decades, astronomers found many examples out in the Universe.

Stars are held in perfect balance by two opposing forces. There’s the inward pressure of gravity, attempting to collapse the star, counteracted by the outward pressure of the emitted radiation.

This artist's concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. Image credit: NASA/JPL-Caltech — This artist’s concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. Image credit: NASA/JPL-Caltech

At the core, millions of tonnes of hydrogen are being converted into helium every second, releasing gamma radiation. This fusion process is an exothermic reaction, meaning it releases more energy than it requires.

As the star consumes the last of its hydrogen, it switches to the stockpiles of helium that it has built up. After it runs out of helium, it switches to carbon, and then oxygen.

Since the star continues to pump out radiation, it balances out the gravitational forces trying to compress it.

Stars with the mass of our Sun pretty much stop there. Not massive enough to continue the fusion reaction, beyond oxygen, they become a white dwarf and cool down.

But for stars with about 5 times the mass of our Sun, the fusion process continues further up the periodic table to silicon, aluminum, potassium, and so on, all the way to iron.

No energy can be produced by fusing iron atoms together. It’s the stellar equivalent of ash.

And so, in a fraction of a second, the radiation from the star turns off. Without that outward pressure from the radiation, gravity wins out and the star implodes. An entire star’s mass collapses down into a smaller and smaller volume of space.

The velocity you would need to escape from the star goes up, until not even light is going fast enough to escape.

And this is how you form a black hole.

Well, that’s the main way.

You can also get black holes when dense objects, like neutron stars, collide with one another.

And then there are the supermassive black holes at the heart of every galaxy. And to be honest, astronomers still don’t know how those monsters formed.

September 23, 2013March 16, 2017 by Fraser Cain

Why Are There Seasons?

We’re in the middle of Summer here on Vancouver Island, the Sun is out, the air is warm, and the river is great for swimming.

Three months from now, it’s going to be raining and miserable.

Six months from now, it’s still going to be raining, and maybe even snowing.

No matter where you live on Earth, you experience seasons, as we pass from Spring to Summer to Fall to Winter, and then back to Spring again.

Why do we have variations in temperature at all? What causes the seasons?

If you ask people this question, they’ll often answer that it’s because the Earth is closer to the Sun in the summer, and further in the winter.

But this isn’t why we have seasons. In fact, during Winter in the Northern Hemisphere, the Earth is actually at the closest point to the Sun in its orbit, and then farthest during the Summer. It’s the opposite situation for the Southern hemisphere, and explains why their seasons are more severe.

So if it’s not the distance from the Sun, why do we experience seasons?

We have seasons because the Earth’s axis is tilted.

Consider any globe you’ve ever used, and you’ll see that instead of being straight up and down, the Earth is at a tilt of 23.5-degrees.

The Earth’s North Pole is actually pointed towards Polaris, the North Star, and the south pole towards the constellation of Octans. At any point during its orbit, the Earth is always pointed the same direction.

For six months of the year, the Northern hemisphere is tilted towards the Sun, while the Southern hemisphere is tilted away. For the next six months, the situation is reversed.

Whichever hemisphere is tilted towards the Sun experiences more energy, and warms up, while the hemisphere tilted away receives less energy and cools down.

Consider the amount of solar radiation falling on part of the Earth.

When the Sun is directly overhead, each square meter of Earth receives about 1000 watts of energy.

But when the Sun is at a severe angle, like from the Arctic circle, that same 1000 watts of energy is spread out over a much larger area.

This tilt also explains why the days are longer in the Summer, and then shorter in the Winter.

The longest day of Summer, when the Northern Hemisphere is tilted towards the Sun is known as the Summer Solstice.

And then when it’s tilted away from the Sun, that’s the Winter Solstice.

When both hemispheres receive equal amounts of energy, it’s called the Equinox. We have a Spring Equinox, and then an Autumn Equinox, when our days and night are equal in length.

So how does distance from the Sun affect us?

The distance between the Earth and has an effect on the intensity of the seasons.

The Southern Hemisphere’s Summer happens when the Earth is closest to the Sun, and their winter when the Earth is furthest. This makes their seasons even more severe.

You might be interested to know that the orientation of the Earth axis is actually changing.

Over the course of a 26,000 year cycle, the Earth’s axis traces out a great circle in the sky. This is known as the precession of the equinoxes.

At the halfway point, 13,000 years, the seasons are reversed for the two hemispheres, and then they return to original starting point 13,000 years later.

You might not notice it, but the time of the Summer Solstice comes earlier by about 20 minutes every year; a full day every 70 years or so.

I hope this helps you understand why the Earth – and any planet with a tilted axis – experiences seasons.

September 19, 2013March 16, 2017 by Fraser Cain

What is a Dyson Sphere?

As long as humans survive, we will likely be increasing our energy consumption. We want better transportation, faster computers, and stuff we just can’t imagine yet.

That’s going to take energy, and lots of it.

If you plot our overall use since the industrial era, you can see it’s a line that just goes up and up. There will come a time in the future when we’ve exhausted all the fossil and nuclear fuels. And once we’ve harvested as much wind, solar and geothermal energy as our planet can produce, we’re going to need to move out into space and collect energy directly from the Sun.

We will construct larger and larger solar arrays, beaming the energy back to Earth. Inevitably, we’ll enclose the entire Sun in a cloud of solar satellites, allowing us to make use of 100% of the radiation it’s emitting.

This is a Dyson sphere.

The concept was developed as part of a research paper in 1960 by the physicist Freeman Dyson. In a thought experiment, he assumed that the power needs for civilizations never stops increasing.

If our descendents could actually figure out how to enclose our star in a rigid shell, we’d have 550 million times more surface area than Earth has right now, and generate 384 yottawatts of energy.

Sounds great, lots of living space and free energy. But there are a host of problems.

There wouldn’t be any gravity to keep anything stuck to the surface of sphere – it would all drop down towards the star and be destroyed. The sphere would be free floating in space, and unless you could keep it balanced in relation to the star, it would eventually collide with it.

Finally, there might not be enough material to build a shell. This advanced civilization would need to make use of all our planets, asteroids and comets. In fact, even if you dismantled everything in the Solar System, you’d only have enough to build a shell about 15 cm-thick.

The physical strength of this material would have to be immense; otherwise the sphere itself would just implode and collapse into the star.

Dyson himself freely admitted that the idea of a rigid shell surrounding a star is unfeasible. Instead, he and others have proposed that civilizations would probably build a dense swarm of objects on independent orbits around their star – a Dyson cloud, or maybe a Dyson ring.

Each solar satellite would be stable on its own, and capable of beaming its energy back to some planet.

Artist's impression of a solar sail. Image credit: NASA — Artist’s impression of a solar sail. Image credit: NASA

You could also build a cloud of solar sails. These objects would be held in perfect balance between the gravity pulling them inward, and the light pressure from the Sun pushing them outward. They wouldn’t need to orbit at all to maintain a static distance from the Sun.

A full Dyson Sphere is probably impossible, but if we assume that alien civilization’s energy needs will continue to grow like ours, it makes sense to search the galaxy for megastructures. Just in case.

Even though the shell would absorb the light and high energy radiation from the star, it would still emit infrared radiation which would be detectable in our telescopes. Even a partial Dyson cloud would give off a telltale light signature as it obscured the light from a star.

This gives us yet another way we could search for extraterrestrial civilizations. And if we did find a full Dyson sphere, out there in the Milky Way. Well, let’s just hope they’re nice aliens.

Update: And as it turns out, we may be closer to finding one that previously thought. Using data obtained by the Kepler probe, a group of planet hunters associated with the Planet Hunters project recently observed light fluctuations coming from KIC 8462852. This F-type main-sequence star, located in the constellation Cygnus, is approximately 1,480 light years (454 parsecs) from Earth.

In their paper, submitted to arXiv, the team offered possible explanations for the light fluctuations, most of which are admittedly problematic. Using high-resolution spectroscopy, spectral energy distribution fitting, and Fourier analyses of the Kepler light curve, they conclude that the most likely scenario is the passage of a family of exocomet fragments.

Another possible explanation that has been ventured is that the light fluctuations could be caused by the presence of mega-structures, which would indicate the presence of sentient extra-terrestrial life. The SETI institute has since conducted radio reconnaissance of KIC 8462852, and their initial findings provided no indications of technology associated with radio signals.

Still, the mere possibility that this could be the first-ever indication of a possible Dyson Sphere in our galaxy is exciting, and has triggered a great deal of speculation and excitement. Stay tuned for more information as it becomes available.

September 17, 2013March 16, 2017 by Fraser Cain

Is There Really a Planet X?

Have you heard there’s a giant planet in the Solar System headed straight towards Earth?

At some point in the next few months or years, this thing is going to crash into Earth or flip our poles, or push us out of our orbit, or some other horrible civilization destroying disaster.

Are these rumours true?

Is there a Planet X on a collision course with Earth?

Unlike some of the answers science gives us, where we need to give a vague and nuanced answers, like yes AND no, or Maybe, well, it depends…

I’m glad to give a straight answer: No.

Any large object moving towards the inner Solar System would be one of the brightest objects in the night sky. It would mess up the orbits of the other planets and asteroids that astronomers carefully observe every night.

There are millions of amateur astronomers taking high quality images of the night sky. If something was out there, they’d see it.

These rumours have been popping up on the internet for more than a decade now, and I’m sure we’ll still be debunking them decades from now.

What people are calling Planet X, or Nibiru, or Wormwood, or whatever doesn’t exist. But is it possible that there are large, undiscovered objects out in the furthest reaches of Solar System?

Sure.

Astronomers have been searching for Planet X for more than a hundred years. In the 1840s, the French mathematician Urbain Le Verrier calculated that another large planet must be perturbing the orbit of Uranus. He predicted the location where this planet would be, and then German astronomer Johann Gottfried Galle used those coordinates to discover Neptune right where Le Verrier predicted.

The famed astronomer Percival Lowell died searching for the next planet in the Solar System, but he made a few calculations about where it might be found.

A young Clyde Tombaugh with one of his famous homemade telescopes. (Credit : NASA/GSFC).

And in 1930, Clyde William Tombaugh successfully discovered Pluto in one of the locations predicted by Lowell.

Astronomers continued searching for additional large objects, but it wasn’t until 2005 that another object the size of Pluto was finally discovered by Mike Brown and his team from Caltech: Eris. Brown and his team also turned up several other large icy objects in the Kuiper Belt; many of which have been designated dwarf planets.

We haven’t discovered any other large objects yet, but there might be clues that they’re out there.

In 2012, the Brazilian astronomer Rodney Gomes calculated the orbits of objects in the Kuiper Belt and found irregularities in the orbits of 6 objects. This suggests that a larger object is further out, tugging at their orbits. It could be a Mars-sized object 8.5 billion km away, or a Neptune-sized object 225 billion km away.

A false-color, visible-light image of Comet ISON taken with Hubble's Wide Field Camera 3. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) — A false-color, visible-light image of Comet ISON taken with Hubble’s Wide Field Camera 3. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

There’s another region at the edge of the Solar System called the Oort Cloud. This is the source of the long-period comets that occasionally visit the inner Solar System. It’s possible that large planets are perturbing the orbits of comets with their gravity, nudging these comets in our direction.

So, feel free to ignore every single scary video and website that says an encounter with Planet X is coming.

And use that time you saved from worrying, and use it to appreciate the amazing discoveries being made in space and astronomy every day.

September 12, 2013March 16, 2017 by Fraser Cain

Why Does the Earth Spin?

In a classic episode of this video series, I did the calculations for how fast the Earth is spinning.

We know the Earth is rotating, but why? Why is it spinning?

Why is everything in the Solar System spinning? And why is it mostly all spinning in the same direction?

It can’t be a coincidence. Look down on the Earth from above, and you’d see that it’s turning in a counter-clockwise direction. Same with the Sun, Mars and most of the planets.

4.54 billion years ago, our Solar System formed within a cloud of hydrogen not unlike the Orion Nebula, or the Eagle Nebula, with its awesome pillars of creation.

Then, it took some kick, like from the shockwave from a nearby supernova, and this set a region of the cold gas falling inward through its mutual gravity. As it collapsed, the cloud began to spin.

But why?

It’s the conservation of angular momentum.

Think about the individual atoms in the cloud of hydrogen. Each particle has its own momentum as it drifts through the void. As these atoms glom onto one another with gravity, they need to average out their momentum. It might be possible to average out perfectly to zero, but it’s really really unlikely.

Which means, there will be some left over. Like a figure skater pulling in her arms to spin more rapidly, the collapsing proto-Solar System with its averaged out particle momentum began to spin faster and faster.

This is the conservation of angular momentum at work.

As the Solar System spun more rapidly, it flattened out into a disk with a bulge in the middle. We see this same structure throughout the Universe: the shape of galaxies, around rapidly spinning black holes, and we even see it in pizza restaurants.

The Sun formed from the bulge at the center of this disk, and the planets formed further out. They inherited their rotation from the overall movement of the Solar System itself.

Over the course of a few hundred million years, all of the material in the Solar System gathered together into planets, asteroids, moons and comets. Then the powerful radiation and solar winds from the young Sun cleared out everything that was left over.

Without any unbalanced forces acting on them, the inertia of the Sun and the planets have kept them spinning for billions of years.

And they’ll continue to do so until they collide with some object, billions or even trillions of years in the future.

So are you still wondering, why does the Earth spin?

The Earth spins because it formed in the accretion disk of a cloud of hydrogen that collapsed down from mutual gravity and needed to conserve its angular momentum. It continues to spin because of inertia.

The reason it’s all the same direction is because they all formed together in the same Solar Nebula, billions of years ago.

September 9, 2013December 6, 2017 by Fraser Cain

How Did the Moon Form?

The night sky just wouldn’t feel right without the Moon. Where did our our friendly, familiar satellite come from?

Scientists and philosophers have been wondering about this for centuries.

Once Copernicus gave us our current model of the Solar System, with the Earth as just another planet and the Sun at the centre of the Solar System, this gave us a new way of looking at the Moon.

The first modern idea about the formation of the Moon was called the fission theory, and it came from George Darwin, the son of Charles Darwin.

He reasoned the Moon must have broken away from our planet, when the Earth was still a rapidly rotating ball of molten rock.

His theory lasted from the 1800s right up until the space age.

Another idea is that the Earth captured the Moon after its formation.

Usually, these kinds of gravitational interactions don’t go well.

Models predict that either the Moon would collide with the Earth, or get flung out into a different orbit.

It’s possible that the early Earth’s atmosphere was much larger and thicker, and acted like a brake, modifying the Moon’s trajectory into a stable orbit around the Earth.

Or the Earth and Moon formed together in their current positions as a binary object, with Earth taking most of the mass and the Moon forming from the leftovers.

Formation of the Moon. — *Artist’s impression of the impact that caused the formation of the Moon. Credit: NASA/GSFC*

The most widely accepted theory is that the Moon was formed when a Mars-sized object slammed into the Earth, billions of years ago.

This collision turned the newly formed Earth into a molten ball of rock again, and ejected material into orbit.

Most of the material crashed back into the Earth, but some collected together from mutual gravity to form the Moon we have today.

This theory was first conceived in 1946 by Reginald Aldworth Daly from Harvard University. He challenged Darwin’s theory, calculating that just a piece of Earth breaking off couldn’t actually allow the Moon to get to its current position. He suggested an impact could do the trick though.

This idea wasn’t given much thought until a 1974 paper by Dr. William K. Hartmann and Dr. Donald R. Davis was published in the Journal Icarus. They suggested that the early Solar System was still filled with leftover moon-sized objects which were colliding with the planets.

The impact theory explained many of the challenges about the formation of the Moon. For example, one question was: why do the Earth and Moon have very different-sized cores.

After an impact from a Mars-sized planet, the lighter outer layers of the Earth would have been ejected into orbit and coalesced into the Moon, while the denser elements collected back together into the Earth.

It also helps explain how the Moon is on an inclined plane to the Earth. If the Earth and Moon formed together, they’d be perfectly lined up with the Sun.

But an impactor could come from any direction and carve out a moon. One surprising idea is that the impact actually created two moons for the Earth.

*The two sides of the Moon. Image credit: LRO*

The second, smaller object would have been unstable and eventually slammed into the far side of the Moon, explaining why the surface on the far side of the Moon is so different from the near side.

Even though we don’t know for sure how the Moon formed, the giant impact theory holds the most promise, and you can bet that scientists are continuing to look for clues to tell us more.

September 5, 2013March 16, 2017 by Fraser Cain

How Could We Find Aliens? The Search for Extraterrestrial Intelligence (SETI)

In a previous video, I talked about the Fermi Paradox.

Our Universe is big, and it’s been around for a long time. So why don’t we see any evidence of aliens? If they are out there, why haven’t they contacted us, and how do we contact them? What methods might they use to try and contact us?

Where do we look for signs of alien civilizations?

The search for extraterrestrial intelligence, otherwise known as SETI, are the methods that scientists have proposed to discover evidence of aliens in the Universe.

Perhaps the most famous method is listening for their signals. Here on Earth, we have exploited the radio spectrum to send signals through the air. We even use it to communicate with spacecraft in the Solar System.

So, since it works so well for us, it makes sense that aliens might use radio waves to communicate from star to star. If there’s an alien civilization out there beaming a signal directly at the Sun, our largest radio telescopes should be able to pick up their signal.

The problem is that the galaxy is huge, with hundreds of billions of stars. Any one of which could be the world where the aliens live. Furthermore, we don’t know which frequency the aliens might use to communicate with us.

Even though the search for ET has been going for many years, we’ve only explored a fraction of the millions of available stars and frequencies on the radio spectrum.

So far, no definitive signal has been discovered.

Gieren et al. used the 8.2-m Very Large Telescope (Yepun) to image M33, and deduce the distance to that galaxy (image credit: ESO).

Another possibility is that aliens are using lasers to communicate with us. An alien could target an incredibly powerful laser at our star, and it would be detectable with our large optical telescopes. There have been a few dedicated searches for laser communication, and scientists have proposed we could search for these alien signals at the same time we’re searching for extrasolar planets.

Again, so far nothing has turned up.

View from inside the Borexino neutrino detector. Image Credit: Borexino Collaboration

It’s possible that aliens use a more exotic method of communication, like neutrinos.

Neutrinos are generated in high energy collisions, and can pass right through planets with ease. They would be incredibly difficult to detect with our current technology, but maybe advances in the future will make that a possible communication method.

But maybe Instead of searching for signals, we could look for their artifacts.

If the energy of transmitting signals across the vast reaches of space is too much, it might make more sense for aliens to construct self-replicating probes and let them journey from star to star.

These probes could leave behind an obvious alien-made structure which we could discover once we become a true spacefaring species.

We could also detect aliens by their impact on their home planets. With a large enough space telescope, we should be able to study the atmosphere of planets orbiting nearby stars. An industrialized civilization would probably be polluting its atmosphere with various gases — just like we have — which would be detectable.

Finally, we could search for evidence of aliens through their structures.

If a civilization starts building megastructures which block off a large portion of their star’s light, we should be able to detect evidence through our search for extrasolar planets.

A gigantic space station would give off a much different light signature than a nice spherical planet as it passes in front of its star.

There have been a few attempts to reach out to other worlds directly, transmitting signals out into space. It’s unlikely that these signals will actually reach any other civilization, and some scientists are concerned about the wisdom of this kind of communication.

Do we really want to alert potentially hostile aliens to our location in the Milky Way?

It’s exciting to think that there are other alien civilizations around us in the Milky Way, and with a little more work, we could discover their location and maybe even communicate with them.

Let’s hope they’re peaceful.

September 3, 2013March 16, 2017 by Fraser Cain

How Big is the Solar System?

For most of us, stuck here on Earth, we see very little of the rest of the Solar System. Just the bright Sun during the day, the Moon and the planets at night. But in fact, we’re embedded in a huge Solar System that extends across a vast amount of space.

Which begs the question, just how big is the Solar System?

Before we can give a sense of scale, let’s consider the units of measurement.

Distances in space are so vast, regular meters and kilometers don’t cut it. Astronomers use a much larger measurement, called the astronomical unit. This is the average distance from the Earth to the Sun, or approximately 150 million kilometers.

Mercury is only 0.39 astronomical units from the Sun, while Jupiter orbits at a distance of 5.5 astronomical units. And Pluto is way out there at 39.2 astronomical units.

That’s the equivalent of 5.9 billion kilometers.

If you could drive your car at highway speeds, from the Sun all the way out to Pluto, it would take you more than 6,000 years to complete the trip.

But here’s the really amazing part. Our Solar System extends much, much farther than where the planets are.

The furthest dwarf planet, Eris, orbits within just a fraction of the larger Solar System.

The Kuiper Belt, where we find a Pluto, Eris, Makemake and Haumea, extends from 30 astronomical units all the way out to 50 AU, or 7.5 billion kilometers.

And we’re just getting started.

Artist's interpretation depicting the new view of the heliosphere. The heliosheath is filled with “magnetic bubbles” (shown in the red pattern) that fill out the region ahead of the heliopause. In this new view, the heliopause is not a continuous shield that separates the solar domain from the interstellar medium, but a porous membrane with fingers and indentations. Credit: NASA/Goddard Space Flight Center/CI Lab — Artist’s interpretation depicting the new view of the heliosphere. The heliosheath is filled with “magnetic bubbles” (shown in the red pattern) that fill out the region ahead of the heliopause. In this new view, the heliopause is not a continuous shield that separates the solar domain from the interstellar medium, but a porous membrane with fingers and indentations. Credit: NASA/Goddard Space Flight Center/CI Lab

Even further out, at about 80-200 AU is the termination shock. This is the point where the Sun’s solar wind, traveling outward at 400 kilometers per second collides with the interstellar medium – the background material of the galaxy. This material piles up into a comet-like tail that can extend 230 AU from the Sun.

But the true size of the Solar System is defined by the reach of its gravity; how far away an object can still be said to orbit the Sun.

The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA

In the furthest reaches of the Solar System is the Oort Cloud; a theorized cloud of icy objects that could orbit the Sun to a distance of 100,000 astronomical units, or 1.87 light-years away. Although we can’t see the Oort Cloud directly, the long-period comets that drop into the inner Solar System from time to time are thought to originate from this region.

The Sun’s gravity dominates local space out to a distance of about 2 light-years, or almost half the distance from the Sun to the nearest star: Proxima Centauri. Believe it or not, any object within this region would probably be orbiting the Sun, and be thought to be a part of the Solar System.

Back to our car analogy for a second. At those distances, it would take you 19 million years to complete the journey to the edge of the Solar System. Even NASA’s New Horizons spacecraft, the fastest object ever launched from Earth would need 37,000 years to make the trip.

So as you can see, our Solar System is a really really big place.

August 27, 2013March 16, 2017 by Fraser Cain

Should Robots or Humans Explore Space?

You might be surprised to know that I have an opinion. People often ask me for it, but tend not to give it. But I was getting into a discussion with Amy Shira Teitel from Vintage Space about the priorities of humans versus robots for space explorations and offered up this opinion.

On matters of humans versus robots exploring space, this is what I think. Both, with different agendas.

Opinion: Should Robots or Humans Explore Space?

What’s the best way to explore the Solar System? Should we send humans, or robots? Robots are durable and replaceable, while humans are creative and flexible.

Space advocates line up on both sides of this discussion, and the debate can get heated.

Really heated.

Don’t be fooled. This whole conversation is a red herring.

We shouldn’t have to choose between human space exploration and robotic science, and it is absolutely ridiculous that the funding for it comes into a single agency.

The future of humanity will depend on us learning to live in space; to get off this planet and spread to the rest of the Solar System. The longer we remain trapped on this planet, the greater risk we face from a global catastrophe; whether it’s from an asteroid strike or a global plague.

We, as a species, are keeping all our eggs in one basket,

I don’t need to tell you how important science is. Our modern marvels are a direct result of the scientific method. The fact that you can even see this video (well, or read this article) should be all you need to know about the importance of science.

And we have no idea what we’ll find out there in space when we go exploring.

Were it up to me, I’d separate space exploration into two agencies, with completely different agendas and budgets.

On the science side, we need a fleet of robotic spacecraft and satellites continuously launching into space. We’d settle on a rugged, multi-purpose vehicle, which carries a variety of payloads and scientific instruments.

Curiosity Rover snapped this self portrait mosaic

The Curiosity Rover was an amazing success, and NASA should just keep building more rovers exactly like it. Give it cameras, grinders and scoops, but then keep the instruments open to the scientific community. Every two years, another identical rover will blast off to the Red Planet, hurling a fresh set of instruments to a new location.

Let’s send a rover and an orbiter every two years to Mars, and similar probes to other worlds, only the scientific instruments would need change. In a few years, there would be versions of the exact same spacecraft orbiting planets, asteroids and moons.

Over time, our observation of the Solar System would extend outward like a nervous system, gathering scientific knowledge at a terrific rate.

Neil Armstrong and Buzz Aldrin plant the US flag on the Lunar Surface during 1st human moonwalk in history - exactly 44 years ago on July 20, 1969 during Apollo 1l mission. Credit: NASA — Neil Armstrong and Buzz Aldrin plant the US flag on the Lunar Surface during 1st human moonwalk in history – exactly 44 years ago on July 20, 1969 during Apollo 1l mission. Credit: NASA

For human space exploration, we need to learn to live in space in increasingly complex ways: low Earth orbit, lunar orbit, on the lunar surface, on Mars, on asteroids, at Saturn, in the Lagrange points, et cetera.

Remember the Gemini program back in the 1960s? Each mission was an incremental step more complicated than the previous one. On one mission, the goal was just to learn if humans could survive in space for 14 days. In another mission, the goal was just to learn how to dock two spacecraft together.

This gave NASA the knowledge they needed to attempt an ambitious human landing on the Moon.

Chris Hadfield in the Cupola of the ISS. Credit: NASA

Instead of flying in low-Earth orbit for decades, our human space program could continuously advance our knowledge of what it takes to survive – and eventually thrive – in space. If NASA investigates the technologies that the private sector considers too risky to invest in, it will help jump start space exploration.

In this modern era of budget cuts, it breaks my heart that people are forced to choose between space science and human exploration.

It shouldn’t be this way. They have almost nothing in common.

Let’s do science, because science is important.

And let’s put humans in space, because humanity is important.