Note (12/2015): Hi there! I'm taking some time off here to focus on other projects for a bit. As of October 2016, those other projects include a science book series for kids titled Things That Make You Go Yuck! -- available at Barnes and Noble, Amazon and (hopefully) a bookstore near you!

Co-author Jenn Dlugos and I are also doing some extremely ridiculous things over at Drinkstorm Studios, including our award-winning webseries, Magicland.

There are also a full 100 posts right here in the archives, and feel free to drop me a line at with comments, suggestions or wacky cold fusion ideas. Cheers!

· Categories: Astronomy, Physics
What I’ve Learned:

Oort cloud: Go way, way Oort -- then Oort a little further.
“Oort cloud: Go way, way Oort — then Oort a little further.”

If you’ve ever played pinball — which you’ve probably only done ironically, if you’re under the age of thirty — then you’re familiar with the concept of “multiball”. You lock balls by making certain shots, and then there’s some way to unlock them, so a bunch of balls all come flying out at once. Sometimes there’s more than you locked. Often, they come from different places than you put them. They fly around higgledy-piggledy from all directions, until you lose them or you tilt the machine or you get bored and remember that video games and the internet and Netflix exist.

But maybe you’ve wondered, while the multiball madness ensues: where are all of these balls coming from? I always assumed there were some nifty mechanics inside the machine, pulling balls from a reservoir and gliding them around. Either that, or gnomes. Very small hippie gnomes. But then I learned something about astronomy, and found there’s another place those balls might be coming from: the Oort cloud.

Mind you, the Oort cloud is purely theoretical. But its existence has been predicted based on questions about our solar system’s own version of multiball — namely, comets. Some comets swing past the sun every few years. The orbits of these “short-period” comets aren’t so large, and most of them originate in either the Kuiper belt, around 30-50 AU (astronomical units; 1 AU is roughly the distance from the earth to the sun) or the overlapping “scattered disc”, which extends from around 30-100 AU.

These regions begin right around the distance of Neptune from the sun, and they’re not so mysterious. Definitely not “multiball mysterious”. Astronomers see Kuiper Belt objects all the time — probably with a decent pair of opera glasses. New Horizons, the space probe that buzzed Pluto a while back, is swooping through the Kuiper Belt right now. It’s practically down the block.

The Oort cloud is a leeeeetle cooler than that. First, it’s just slightly further away, occupying the space somewhere between around 2,000 – 100,000 AU, give or take a light year. (Which, as it happens, is about 50,000 AU. So it’s true!)

For perspective, that Voyager I probe launched back in 1977? You know, back when people actually played pinball (because it was either that or Pong, those poor primitive saps)? That craft has traveled further than any other we’ve made, it’s technically in interstellar space, and is traveling at around 38,000 miles per hour (a shade faster than New Horizons; don’t tell the Space Highway Patrol). Voyager is expected to enter the Oort cloud in roughly 300 years — or about 290 years after its radioisotope-powered generators are expected to fail, leaving it a silent hunk of space rubble.

So the Oort Cloud is a big ol’ faraway ball of space, is what I’m saying. Inside it are theorized to be trillions — that’s trillions, with a ‘truh-‘ — of objects at least one kilometer across. Most of these are icy bodies, but there are few (meaning few billion) rocky asteroids sprinkled in, just for fun. It’s thought that Oort cloud objects mostly come from debris left over from the formation of the solar system, when the original “protoplanetary disc” swirled into Saturn and Jupiter and Earth and the rest of the planetary gang. Some even theorize that part of the Oort cloud — up to 90%, at the upper end — comes from “sister stars” that were closer by during the sun’s early days, and spewing pre-planetary spittle all over the cosmos themselves.

But if we’ve never seen the Oort cloud, then why would we think it’s out there? Why don’t we just assume there’s nothing there, or space gnomes, and be done with it? Because of long-period comets, that’s why. When astronomers track the orbits of these comets, they see some that make a circuit in hundreds or even thousands of years. And unlike comets from the Kuiper belt or scattered disc, which lie flat in the same plane as the planets, these long-period take-your-time-grandpa comets come from everywhere.

So that’s the Oort cloud. Further out than we can see, surrounding our whole solar system and occasionally raining some of its trillions of balls of ice and rocks down on our pinball machines. Ding ding ding. Multiball, indeed.

Image sources: Universe Today (Oort cloud), Zazzle (MULTIBAAAAAAALL!), French Vocabulary Illustrated (opera-glassed stargazing), Drawception (space gnome [artist’s rendering])

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· Categories: Astronomy, Physics
What I’ve Learned:

Heliosphere: It's the sun's Twinkie. We're just along for the ride.
“Heliosphere: It’s the sun’s Twinkie. We’re just along for the ride.”

There are many complicated models of what our solar system looks like. Then there’s my model: the solar system is like a giant Twinkie, with a Red Hot candy jammed in one end.

Seriously, NASA. Why make things hard, when they could be so delicious?

So here’s how the Twinkie squishes:

The Red Hot, naturally, is the sun, radiating loose particles and waves of heat in all directions. With the candy, most of the particles are artificial cinnamon flavor and FD&C red #5, and they only make it as far as the nearest taste bud.

With the sun, the particles are solar wind — a plasmafied soup of protons and electrons — and they shoot outward at roughly 1.2 million miles per hour, give or take a speeding bullet or two.

The sun is therefore much more powerful than a Red Hot candy, but considerably less appetizing. And, so far as we know, non-fat. If you’re into that sort of thing.

Back to the model. The Twinkie represents the full spread of solar material, a region called the heliosphere. This bubble of sun-spewed plasma extends roughly 120 astronomical units — or A.U., the distance from the earth to the sun. That’s a very long way. Even wasabi pea particles don’t make it out that far.

The heliosphere doesn’t extend equally in all directions, though; hence the “Twinkie-shapedness” of the model. Remember that our sun is also constantly whirling around the galaxy at breakneck speed, which stretches the plasma bubble out behind it. Imagine the Twinkie as a speeding race car, with the Red Hot near the nose.

Or a Twinkie jet plane, if you like. Any method of theoretical Twinkie locomotion you prefer is fine. This is one of the main perks of stellar science, from what I understand.

The final bit of the heliosphere model is the outer part, where the delectable Twinkie cream turns into scrumptious Twinkie cake. In space, this interface is called the termination shock, and it’s where those plasma blasts from the sun finally slow down below the speed of sound. This happens when the solar wind interacts with the interstellar medium, a haze of gas and dust and cosmic rays flowing between the stars.

As the interstellar medium slows down the solar rays, the plasma stagnates and bubbles and clumps up — much like the spongecake cradling our Twinkie. This layer is called the heliosheath, and is immediately followed by the heliopause, where the solar wind finally disappears entirely. It’s the thin brown crust that marks the final boundary between Twinkie and not-Twinkie. When you pass the heliopause, you’re no longer in the solar system.

So how many man-made objects have made this journey out of the heliosphere, to boldly go where no Twinkie has gone before? One — or possibly none. Voyager 1, launched in 1977 to explore the outer planets, has been hurtling directly away from the sun at eleven miles per second since 1980. It’s believed that in August of 2012, Voyager 1 passed through the heliopause and out of the sun’s fiery clutches.

But because we don’t precisely know what the end of the solar system looks like, researchers are still proposing and conducting tests to determine exactly how “out” Voyager 1 is. If not yet, then it’s expected to pop through the heliopause within the next year or so, followed soon by Voyager 2.

(And if my petition to NASA goes through, next by Guy Fieri.)

Breaking an object out of the heliosphere will be quite an accomplishment, once confirmed. But why anyone would run away from a cinnamon-flavored Twinkie is beyond me.

Image sources: PlanetFacts (heliosphere diagram), Perfectly Crazy (Twinkie racer), DeviantArt / Jonnyetc (Winston’s big Twinkie), Rock ‘n Roll Ghost and GeekDad (Voyager Fieri)

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