Category Archives: conspiracies

Comet Elenin: Scientific Facts vs. Bravo Sierra

Get Your Straight Skinny Right Here

I used to study comets for a living.  They’re iceballs, mixed with a little dirt.  They’re pretty small as solar system bodies go — often not more than a couple of miles (or kilometers across). They orbit the Sun just like planets do, and once you know a comet’s orbit (or any solar system object’s orbit), you can predict it pretty well.  They don’t suddenly change their orbits without reason (see Kepler’s laws of Planetary Motion, which apply to comets and asteroids in general (see discussion under “First Law”) as well, to understand why).

To really “get” what a comet is and does, the next time it snows in your neighborhood, take a handful of snow and mix it with some dirt.  If it doesn’t snow, then go get a snowcone or get some chipped ice and mix it with dirt to make an iceball.

Heft it in your hand. Look at it.  It’s not very dangerous on its own, is it? Common sense tells you that it doesn’t have much mass, it doesn’t have a strong gravitational pull.  If you could build a snowball maybe a mile or two across and put it into orbit around the Sun, you’d have a comet.  Most comets are made of water ice, with traces of other ices mixed in (carbon dioxide ice, methane ice, stuff like that that we know the physical principles of).  They orbit the Sun, often in very long orbits that take them out beyond the orbits of Mars, or Jupiter or even Neptune.  There are many, many comets and each one has the same basic makeup and long orbits.  I findthem fascinating because of what they are and where they came from, and what they tell us about the solar system’s history.

The true value of comets is really what they tell us about the conditions in which they formed.  that’s what always kept me interested in the comets we studied. Each one carries a treasure trove of chemical information about the elements in and conditions prevailing in the early solar system.  In the original solar nebula, the cloud of gas and dust from which the Sun and planets formed, gases such as hydrogen, oxygen, nitrogen and so forth were pretty abundant. So were grains of dust and water and other molecules. Because space temperatures are cold, many of the molecules existed as frozen ices.

As the conditions at the center of the nebula warmed up (where the Sun was forming), the hot bright radiation of the protosun destroyed any icy material that existed nearby.  Only the icy materials and gases in the far reaches of the solar system (mostly out beyond Jupiter,where the temperatures were cold enough to support icy objects) survived.

Comets come from a reservoir of icy chunks that has existed beyond Neptune’s orbit since the very earliest epochs of solar system history.  All these objects — collectively grouped as Oort Cloud objects — orbit the Sun, but at very huge distances.  And, as I mentioned above, they carry the chemical evidence of what it was like in the early solar nebula. That makes each comet a treasury of information.

So, how do comets get to the inner solar system?  Their orbits are changed by entirely normal and scientifically understandable circumstances. Since they’re small, it doesn’t take much to nudge a cometary nucleus from its orbit into a slightly different orbit — one that takes it closer to the Sun. The most logical and commonsense suspects for such gravitational nudges would be nearby planets (dwarf or otherwise), or possibly a passing star (and yes, stars can do that) at the very edges of the solar system.  Spacecraft (alien or otherwise) would not be big enough to nudge a cometary nucleus, but a close pass with a body the size of Pluto, for example, would.

Anyway, once nudged, the cometary nucleus is on a new orbit — and often times that orbit is one that takes it in toward the Sun and through the orbital paths of other planets and asteroids.  As a comet gets closer to the Sun, it feels more of the Sun’s gravitational pull, and—at that point, you can see how Kepler’s laws really do work—a comet’s orbit is shaped by the gravitational tug of the Sun and any planetary bodies it flies close to.  If it happened to get close to Earth, it might be affected by that, for example.

This is all very natural and, if you understand what orbits are and how they evolve over time due to natural forces, then you “get” what comets do. They’re frozen chunks of ice and dust, following paths set in motion a long time ago

So, there’s this comet called Elenin doing its closest pass to the Sun during its elliptical orbit.  It’s doing what all things in orbit around the Sun do—which is completely normal and nothing to be worried about.   Its path will take it close enough so that we could spot  it, but not close enough that it’s going to do anything to us.  Even if it passed really close to Earth, its mass is so small and its body so inconsequential that nothing would happen. Really.

Comet Elenin as seen by STEREO spacecraft, August 6, 2011. From Earth, presently the comet is a faint smudge of light in deep sky exposures. By late August comet Elenin could be visible to the naked eye as a dim "fuzzy star" with a tail.

So, here’s the skinny on Elenin’s appearance in our skies. On October 16 of this year, it will be approximately 22 million miles (35 million kilometers) from Earth. That is 90 times the distance between Earth and the Moon (which lies around 238,000 miles (~333,000 kilometers) away).  It’s probably not going to be very bright in the sky, and you may need binoculars to see it. So, it’s not really the brightest comet to come into the inner solar system. Certainly many amateur and not a few professionals will take a look at it, and measure its tail and gas out put to help understand its chemical makeup. But, that’s about it.  Another entirely normal cometary appearance in the solar system.

There are a LOT of people out there, posting on the Web about how Elenin is going to blot out the Sun, or align with some other celestial body and cause trouble for Earth in some other way. Some of the stuff I’ve read even invokes unknown aliens, UFO fleets (that nobody except the Bravo Sierra vanguard can see), suddenly appearing and disappearing mysterious spacecraft, and other ad hoc fantasies. It’s like reading about the Bermuda Triangle or voodoo economics—lots of Bravo Sierra, few (if any) provable facts.

It really is all nonsense. There’s no other polite way to put it.  These fantasies are written by people who haven’t taken the time to learn the basic laws of physics and Kepler’s motions. It’s kind of like reading financial news from people who don’t understand how money works or soccer stories written by people who don’t know the rules of the game.

How an object as small as Elenin could blot out the Sun from a distance of 22 million miles makes me laugh. This is a really small comet. If you were looking directly at the Sun (never a good idea though—since it would burn your retinas in a few seconds, so don’t even think about it) and the comet passed between us and the Sun, I doubt you’d even see the difference.  That is, if you could see at all after staring at the Sun that long. Do you really want to trust your eyesight to idiots on the Web who post such nonsense?  So, why trust their “scientific knowledge”?  That’s right. You wouldn’t.

You probably should read all the nonsense though—it’s always good fine-tune your Bravo Sierra Detector(TM), especially as we head into an election year in the United States. And, in these tough economic times, a little laughter at silliness can be a good thing, as long as you know it’s silliness.  I know that logic and the laws of science are sometimes less enticing and entertaining than out-and-out nonsense.

Before you do wade through the Web-enabled fantasies about this comet, arm yourself with some scientific facts.  Check out the Comet Elenin FAQ, written by people who know the science of comets. The more you know, the less likely it is you’ll be taken in by purveyors of Bravo Sierra.

It’s the End of the Year… We’re Still Here…

So Far

Well, another year has come and gone and Earth hasn’t been blasted apart by rogue asteroids, visited by aliens, irradiated by killer space beams from the center of the galaxy, or any of a bunch of other pseudo-scientific “death from the cosmos” scenarios that get floated around the IntarWebs every year. I don’t know about you, but I’m relieved. Of course, it’ll all start up again (does the ignorant rumor-mongering ever quit?) in the New Year. I’ve already been getting a few spam mails from people trying to convince everybody that the year 2012 is the End of Time As We Know It, as supposedly predicted by the Maya people, the flying saucer people, the Greys, the Pleiadians, the Trilateral Commission, the Planet X/Nibiru/N*ncy-Bot people, and all kinds of other folks who seem to take endless delight in making up stuff out of nothing and then using it to scare people/sell stuff/get attention. Chances are you’ve read about their “predictions” from time to time, and hopefully you’ve laughed at their endless prattling in blogs (complete with CAPITAL LETTERS AND LOTS OF !!! AND ??? and silly comments like “No one has ever seen this before” and “NASA is baffled” and “the truth the government doesn’t want you to know about aliens” and other such horse manure).

Now, just because these paranoid shills are making stuff up about the cosmos doesn’t mean that the cosmos is a benign place. Quite the contrary.  For example, there ARE asteroids out there.  Thousands of them.  Most of them are in the Asteroid Belt and are quite likely to stay there, happily orbiting the Sun until the end of time. But, there are other asteroids on their own orbits, some of them quite close to the Sun and which could pose a danger to any of the planets whose orbits they intersection (and not just Earth).

Since its formation some 4.5 billion years ago, Earth and all the other planets, have been bombarded by asteroids and comets.  That’s the nature of life in the solar system.  If you look at it from a systems evolution standpoint, it’s completely obvious that planets are going to get smacked at some point in their histories.  It’s not terribly different from putting a bunch of race cars in a racing oval and letting them go.   The race evolves from a bunch of cars in their own lanes to cars that might collide, which then causes other collisions, and eventually you could have cars smashed together into bigger balls of debris.

The early solar system was not made of cars, but it was full of debris circling in orbit around the newborn Sun.  Those chunks of ice and rock ran into each other, or were gravitationally attracted to each other. As planets coalesced from that debris, they collided with the leftovers as they, too, orbited the Sun. Earth and all the other planets have pretty much swept their own orbits relatively clean of debris. But, there’s still a lot of debris left over, and each of those pieces (the comets and asteroids) are on their OWN orbits.

What a major impact event on Earth might look like. Courtesy NASA.

Sometimes those orbits intersect another planet’s orbit.  And, the inevitable happens — a collision. That’s true of every world in the solar system. And, of course, that includes Earth.  Its  orbit intersects orbits of asteroids.  Now that we’re getting better at detecting those asteroids, we can predict when such intersections might occur.  I say “might” because a given orbit can change over time as the object gets a little gravitational “kick” from nearby worlds.  So, if we spot an asteroid today, astronomers plot its path using the discovery and followup observations.  If that asteroid’s orbit takes it close to a larger body (such as a planet), it could pick up that gravitational kick, which would alter the orbit slightly.

Asteroids and comets don’t suddenly veer off course, as I’ve read in some breathless prose on the IntarWebs. In particular, they don’t just jump from one orbit into another on their own volition just because they feel like or because some mystical space beam is pushing them along.  They have to be physically acted on from another body or force. And, those forces have to be pretty big to overcome the orbital inertia that asteroids and comets have. Nor are nearby spacecraft  powerful enough to do it, so that blows the “aliens are sending asteroids toward” us theories out of the water.  It takes a big body, like a moon or a planet, or a lot of gravitational force, or a collision with another body to create the nudge that affects an asteroid or comet orbit. Interestingly, in the case of comet nuclei in the outer solar system, a passing star could supply the gravitational nudge to dislodge a nucleus or several, sending them on headlong trips toward the Sun.

The worlds of the solar system are bombarded constantly – make no mistake about that. Earth itself sweeps up incoming debris all the time. Most of it is dust, but sometimes bigger rocks fall from space and hit the ground. This is entirely normal and, unless it’s a HUGE rock, nothing to worry about.  And, when a big rock does take aim at us, that, too, will be entirely normal. It’s what happens in solar systems. And, instead of devoting our mental capabilities to making up and believing mystical BS about asteroids and killer x-rays and all that other horse manure that passes for pseudo-science these days, it’s best if we spend time understanding just how the orbits of worlds play a part in these entirely normal and rarely world-shaking events.  That’s the nature of science — and science is what opens our eyes to the wonders of the cosmos.

So, here at year’s end, take some time to enjoy the cosmos for what it is — and what it does. Not what somebody imagined it to be in order to scare you or to sell you a book or get you to believe in their cock-eyed theories that don’t stand up to reality.  It’s a wonderfully fascinating cosmos.

Note: my old friend Phil Plait (The BadAstronomer) has written a wonderful book called “Death from the Skies” that examines a lot of “end times” scenarios that the cosmos can throw at us — in great scientific detail and a wonderful sense of humor. Check it out!