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:

Orbital decay: Life's a drag, and then you burn. Or worse.
“Orbital decay: Life’s a drag, and then you burn. Or worse.”

Gravity is scary. Like, horror movie monster scary.

Think about it; gravity is relentless. Just when you think you’ve lost it, there’s gravity behind you, shaking its chainsaw or hockey mask or Lee Press-On fingerblades at you. And it’s sneaky; even if you make it to the abandoned cabin where the lights don’t work and the caretaker killed a busload of nuns exactly fifty years ago tonight, gravity will be inside, lurking in the shadows. You can hide under the covers, but gravity is already under the bed.

Face it — you’ll never escape gravity. If it weren’t the earth yanking you down, it’d be the sun or Jupiter or a rogue black hole. The pull is inevitable, like iron toward a magnet. Or Paula Deen toward butter.

But you can reach a truce with gravity — temporarily. With just the right velocity, your momentum will exactly counteract the force of gravity toward, say, the planet below. You don’t fly away, and gravity doesn’t splat you onto Earth; instead, you achieve a “stable orbit” and circle around and around.

But like Jenga towers and Facebook relationships, things aren’t really as “stable” as they seem. The truce falls apart over time, leading to something called orbital decay. Gravity wins, and the orbiter takes a nose-dive toward the orbitee.

When orbital decay happens to artificial satellites — like space station Mir or the Hubble telescope — one of two things comes next: some space scientist will push the satellite further up to counteract gravity, or it will plummet toward Earth, incinerating (we hope) in the atmosphere on the way down.

Other bodies experience orbital decay, too. Moons, for instance, can get sucked into their planets and destroyed; no Death Star laser beam required. Stars collide, and really wish they hadn’t. Even galaxies and black holes, circling for millions of years, can eventually experience orbital decay and smush each other stupid.

So what causes orbital decay? And why can’t we have nice things, cosmically speaking?

A few reasons. The balance between “orbiting” and “plunging toward destruction” is precarious; the slightest nudge can throw it off. Near a planet like Earth, tiny molecules of gas making up the sorry excuse for a high-altitude atmosphere will do it.

Satellites plow through these specks of gas, no problem — but they do get slowed down, infinitesimally. Those orbital brake-taps add up, and eventually cause a slight drop in altitude — down to where the atmosphere’s thicker, which leads to more slowing, and further dropping, and so on. It’s a vicious spiral, ending with a satellite faceplant from ten thousand miles high.

But there’s more than one way to decay an orbit. A lumpy orbitee, for instance — if the mass of a planet or star isn’t distributed consistently, orbiting bodies will get whanged around by the irregularities until they finally cut loose. And if the orbiter is large enough, it can bring this fate on itself by creating tidal forces on the larger body that squeeze it out of shape.

(This is why most satellites take spin classes, just to stay trim.)

Really huge orbiters have another problem: gravitational radiation. When supermassive objects like neutron stars orbit each other, Einstein’s general relativity theory predicts that gravitational energy waves streaming away from them should cause orbital decay over time. In recent years, astronomers have found binary stellar systems that appear to behave just the way predicted by the theory, which some didn’t expect. Even dead for sixty years, Einstein’s still smarter than a lot of physicists. But even he couldn’t escape gravity.

And neither can you; even if you negotiate with it, gravity has friends who will sneak up and kneecap you, just so gravity can finish you off. It’s like Freddy Krueger, backed by gremlins. Or Chucky with a nest of facehugging aliens. Or Jason Voorhees with a horde of zombie henchmen. And that’ll put the “decay” in your “orbital decay”, let me tell you.

Image sources: A-Level Physics Tutor (orbital decay), Houston Press (Paula Deen, butterface), Me and My Bread Knife (Facebook relationships), PsychoBabyOnline (Jason with machete, no zombies)

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

Trans-Neptunian objects: Stuck where the sun don't shine (very much).
“Trans-Neptunian objects: Stuck where the sun don’t shine (very much).”

In the beginning, there was the Earth.

Meaning, that’s the first solar system object humans knew about, mostly because we kept tripping and falling face-first onto it. Early humans weren’t particularly coordinated.

The sun was also pretty hard to miss, what with the light and heat and occasional scary eclipses. By the 2nd century B.C., eagle-eyed up-gazers had also spotted Mercury, Venus, Mars, Jupiter and Saturn. Not bad for people who didn’t have a LensCrafters at the local mall, probably.

It took a couple thousand years — and eyeglasses, binoculars and telescopes — to find the remaining (current) planets, Uranus (1781) and Neptune (1846). And then we had a problem. Based on calculations of the outer planets’ masses and shapes and favorite Hostess snack cakes, it appeared they were being influenced by some unseen astronomical force — other objects, further out, pulling the strings on Neptune’s orbit. (And pre-packaged dessert preference, apparently. Team Ho-Hos forever.)

So scientists went looking for these mystery bits of rock, called “trans-Neptunian objects”, because they spent (most of) their time chilling outside the orbit of Neptune, thirty times further from the sun as Earth. In 1930, they found the first trans-Neptunian object, and called it Pluto.

On the good side, Pluto was pretty much where astronomers thought it would be. On the bad, it wasn’t large enough to explain the discrepancy in Neptune’s behavior. Better measurements of Neptune determined its orbit actually made perfect sense, so they chalked it up to dumb luck, Pluto became the ninth planet, and nobody looked much for more trans-Neptunian objects for a while.

But Pluto seemed awfully lonely, way out there in a dusty corner of the solar system. So when a second trans-Neptunian object was spotted in 1992, the search was on again. Since then — because even our telescopes have LensCrafters now, probably — more than 1,500 trans-Neptunian objects have been found. So many, in fact, they get grouped into weird classifications like “twotinos” and “cubewanos” and “plutinos”.

(It sounds like the lineup for a Saturday night at the Mos Eisley cantina. But that’s really what they call them.)

All this family reunionizing was great for Pluto, presumably — until it wasn’t. In 2005, a trans-Neptunian object called Eris was found. It looked like Pluto. It had a moon, like Pluto. And it was bigger than Pluto — but no one was quite convinced it should be called a planet. So astronomers got together in 2006 and worked out criteria that said no, sorry, Eris is not technically a planet.

And oh, by the way, if you use the same criteria, neither is Pluto. Ouch. Finding Eris was like going on a date with someone who you don’t like very much, and instead of making you miss your previous relationship, you just realize you had bad taste in dating all along. Maybe you should try OKComet instead.

But there’s more. As astronomers discover even further-out hunks of rock — called extreme trans-Neptunian objects, because they drink Red Bull and get tattoos and stay out past curfew, I assume — an old problem reemerges: they don’t look quite right. In fact, a recent paper studying the orbits of some of these way-out objects says that apparently they are being influenced by something (or somethings), legitimately planet-sized and dark and mysterious even further out. So far, scientists haven’t seen them — or agree they exist — but some are now squinting their telescopes outward, just in case.

Here’s hoping they have a good LensCrafters nearby.

Image sources: NASA/JPL-Caltech (Sedna, the sexy TNO), and FreePik (‘Scopes heart LC), Princess Burlap (“I said, Team Ho-Hos!”), Electronic Cerebrectomy (Mos Eisley cantina band), FB-Troublemakers (sad Pluto)

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

Exosphere: It's where the innie space becomes an outie.
“Exosphere: It’s where the innie space becomes an outie.”

The earth’s atmosphere is sort of like a family. Everybody stays pretty close… but some stay closer than others. So the troposphere, the nearest layer, is like that aunt who comes over every weekend you can’t get rid of. The mesosphere, you maybe see at holidays, and it sends you stupid-looking sweaters for Christmas.

Or pictures of itself in stupid-looking sweaters. The mesosphere’s side of the family was always a little weird.

But the exosphere? No. The exosphere is the black sheep of the atmospheric family — and it likes it that way. You might get the exosphere to RSVP “NO!” to a family reunion, but that’s about it.

In planetary (as opposed to familial) terms, the exosphere is the outermost layer of influence, where individual molecules are still bound by gravity, but there’s nothing you could call an “atmosphere” to be found. Around Earth, the exosphere contains hydrogen, with a little bit of helium, carbon dioxide and oxygen flitting around. But not in a crowded way. It’s less “Times Square at rush hour”, and more “fans at a Miami Marlins baseball game”.

The spot where the exosphere begins is called the thermopause. That might sound like a fancy name for “hot flashes” — and if you happen to be a planet, that’s not too far from the truth. The thermopause marks the boundary of the Earth’s energy system, and the exosphere doesn’t have enough molecular oomph to be part of that.

Of course, the planet has good and bad days, just like the rest of us. So on a high-energy day — maybe it’s summer, or the sun is flaring, or Earth got its ass out of bed early for yoga — the exosphere might start six hundred miles or more above the surface. On days with less energy — Sundays, I’m assuming, and the day after Thanksgiving — the exosphere might start half that high, around three hundred miles up. Some days it’s just harder to push yourself up against outer space, you know?

Where the exosphere ends depends on how you feel about outer space. Or at least how you feel about defining it. If you prefer your outer space to start where the radiation from earth ends — light, heat, the glow from Ryan Seacrest’s front teeth, all of that — then your exosphere ends six thousand miles above the earth, give or take a few hundred miles.

If you want to be all technical about it, and consider where the gravitational pull of the earth on atoms of hydrogen gives way to radiation pressure from the sun, letting those atoms escape out into the ether, that’s a different story. That happens a wee bit further out — say, a hundred and twenty thousand miles up the chute. Or halfway to the moon, if we’re getting other celestial objects involved now.

Speaking of which, other globs of space rock — including our moon — have exospheres, though at lot of them don’t have much of anything else. So an exosphere is sort of the bare minimum possible, in lieu of something more substantial.

Kind of like Ryan Seacrest, apart from his teeth — or the stands at a Marlins game. Neat.

Actual Science:
Universe TodayExosphere
University Cooperation for Atmospheric ResearchExosphere – overview
Science DailyHow the moon gets its exosphere
CBS NewsNASA moon mission targets lunar dust, “exosphere”
University College LondonDione’s thin oxygen exosphere

Image sources: Surfline (atmospheric layers), (Christmas sweater), Buzzfeed (Marlins fans [both of them]), The Richest (Tom Cruise’s shiny, angry, shiny teeth)

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

Gravitational lensing: mirror, mirror in the sky; show me what's behind this guy
“Gravitational lensing: mirror, mirror in the sky; show me what’s behind this guy.”

If you’ve ever sat behind a really tall person at a movie, then you know the infuriating problem of not being able to see something on the other side of a solid object. At the theater, you probably deal with this in the usual ways — hoping the heighty person slouches in their seat, or spontaneously loses six inches of height, or their head explodes like in that Scanners movie.

But astronomy tells us there’s another viable option, known as gravitational lensing. All you have to do is push the movie a few million light years away, and make that big fat head in front of you as dense as a ten-billion star galaxy.

It’s a little complicated. I’ll explain.

One of the (now-famous) predictions of Albert Einstein’s general theory of relativity is that space (really spacetime, but who’s counting?) is curved, and that hugely massive objects with lots of gravitational force will further warp that curving. So if a celestial light source — like, say, a quasar — lies behind an enormous gravitational well such as a galaxy, the light from the quasar would get curved around the galaxy and slingshot out the other side.

It might appear that the light source lies beside the big heavy thing in the way, because the light doesn’t bend all the way back to the middle. And if the source is directly behind the obstacle, the light could take more multiple paths around it — left, right, up, down, south by southwest — and appear more than once on our side. It could even form a full ring of light all around the object in the middle, weirdly indicating that the thing producing the light isn’t anywhere around the obstacle at all, but directly behind it.

I know, right? It’s spooky. Real call is coming from inside the house stuff.

Because Einstein described relativity, and was a generally awesome dude, the light rings caused by gravitational lensing are called “Einstein rings”. There are very few complete rings — caused by a massive energy source directly behind a star or galaxy — but hundreds of partial rings, multiple-image systems and other gravitational lensing events have been observed. One of the most impressive, called Einstein’s Cross — because, again, cool smart guy — consists of four “bent” images of a way-distant quasar curved around a still-way-distant-but-not-as-way-distant galaxy in between.

It’s like having a head in the way, but still seeing the movie in double-stereo-vision. Because astronomy makes everything better.

So what do you need to make gravitational lensing work? First, a source of some kind of energy. Many of the known ones work in visible light, but any kind of electromagnetic energy will do in a pinch. The universe isn’t picky.

The energy source has to be ridiculously strong, though, because you’ll need to see the signal from way far away. Not just from down the block, or from that window in your attic, either. Instead, from billions of light years away. Which is kind of a big deal.

Why so far? Because you then need to find an incredibly massive object to plop between you and the energy source to produce the gravitational lensing. A bowling ball isn’t going to do it. A star might, if it’s in precisely the right orientation. A whole galaxy of stars would be better. Or you could try Nicki Minaj’s ass. It’s big enough to attract most of the pop culture paparazzi into a close orbit, apparently. Maybe it could work; I don’t know.

The point is, you’ll only see gravitational lensing by throwing that hypermassive whatever between you and and the signal. And then you can watch that gravity well bend electromagnetic waves like Beckham, off a straight line and down to your eyes.

So maybe it won’t help you the next time you’re blocked at the movies. But gravitational lensing could show you a star behind another star some day. And really, isn’t that how the movie industry works in the first place?

Image sources: Cosmic Chatter (Einstein ring), Slate (big head at movie theater), Disease Prone (Scanners head), SlamXHype (rocket-powered Minaj)

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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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