New Earth Found!...we think

I know I've been posting pretty much every day this week, and I wanted to space it out so I appeared less obviously blogpolar (blog bipolar). But this one is just too exciting to leave for later. I love the annual astronomy meetings, you always get so much cool stuff from it. Today's news (and yesterday's, which I was going to write a post on anyway) comes from the Kepler probe. Its job is to look for all the planets it can possibly find, and it's doing its job remarkably well.

Previously, all we had was some observations of huge Jovian planets (large gas giants like Jupiter, hence Jovian -- Jove was the Roman name of Jupiter) very close to their stars. Some people thought that perhaps our planetary system was rare after all, and that these huge gas planets were more common. However, the actual explanation was that these kind of systems are just easier to see. This is mostly for two reasons:

1. The shorter period of a small orbit; if the planet goes around its star more than once in a month, say, or a year, we're more likely to see it. We don't usually stay watching the same star for months or years at a time, ruling out most planets that have years about our own length.
2. The larger a planet is, the easier it is to see. Both of our main planetary detection methods are biased towards high-mass planets. The radial velocity method measures how much a star wobbles because of its planet's gravitational pull (more wobble = higher mass planet = easier to detect), and the transit method detects planets by measuring variations in starlight brightness (bigger planet = less starlight during planetary transit = easier to detect).

So NASA decided to send Kepler up to watch the sky and record as much as it possibly could about the mass, composition, and period of every planet around every star that it could find. And its data is getting released this week. Already, we have the news (click here) that there is a super-Earth orbiting a Sun-like star's habitable zone. To boil it into totally non-technical terminology, we think we found a planet that is a prime candidate to have life we would actually recognize! Or we found our Plan B to escape to, when our Sun explodes, our planet freezes from climate change, or we blow ourselves up. However you want to think of it.

The news they released yesterday was very nearly as cool, for a real nerd. As you can see here (click here) -- please don't bring up my obsession with data sets, I'm well aware of it and have sought help (read: sought employment) -- Kepler's data has successfully righted our view of the Universe as far as exoplanets are concerned. The proportions of Jovian worlds has dropped significantly. The estimates now stand at 1 in every 6 stars having an Earth-like planet; that's over 16 billion possible places with recognizable life in our galaxy alone. Think about that...

Unfortunately, it still looks as though slightly larger worlds in closer orbits are more prevalent, but there's no reason to think that this isn't still due to our technology's limitations. The fastest-growing segment by far is the Earth-like planets, and the orbital size is growing as well. The longer Kepler looks, the more distant planets it will find.

Physicists are claiming that this is the year we will find our second home. It's January, and we may already have done it.

Now we just have to figure out how to get there. Alcubierre warp drive, anyone?

Sun Science Part 3

Apologies for this taking too long to write out...Anyway, where was I? Ah yes, solar events and space weather! (Heavens above, so many sentences starting with an A! Alpha alliteration!) I'm not going to bother with the aurora borealis/australis, because it's so well-known that I figure it's not worth talking more about. Here goes:

Solar wind: This is made up of all the charged particles and plasma that escapes the Sun's enormous gravity and shoots off at near-light speed in all directions. If it sounds dangerous, it is. This is one of the many things that astronauts have to protect themselves against when they go into space. It's a boatload of radiation; you think a sunburn is bad? The Earth's atmosphere blocks or absorbs 45% of the energy that hurdles towards us from our star (cute infographic from NASA here). At least it used to, but that gets into a lot of complicated conversations about ozone and other things for which I don't have the chemical background. Suffice it to say, we'd fry if we were outside (or without) the atmosphere.

It's not just scattering from ozone or air and water particles, the magnetosphere helps buffer us as well; think of rain on a windshield. The rain may be blowing directly at the driver, but it hits the windshield and is deflected upwards, never reaching the occupants. The same thing happens with the Earth and the magnetosphere: solar wind streams at us, but since it is composed largely of ions (charged particles), they are deflected by the magnetic envelope around our planet, channelling north or south to the poles, where the magnetic lines reach down into the Earth.

Sunspots: these are irregular dark areas on the Sun that, honestly, we can't quite understand. They're caused by fluctuations in the magnetic fields under the surface (remember the lines in the hot gas are like seething spaghetti, it isn't neatly ordered), and they're cooler than the rest of the Sun's surface. That's why they're darker. We know that they tend to be more common during the peak of the 11-year solar cycle, and they show up less often during solar minimum (the technical term for sunspot off-season). We also suspect that longer-term quiet periods of sunspot activity have led to massive cold snaps on the Earth...massive as in the last time there was a significant dearth of sun spots -- known as the Maunder Minimum -- we went through the little ice age of the 17th century. 

So if we know all that, what do we not understand about sunspots? Well, we don't know really why they form (the solar cycle is a mystery, all we know is the "spaghetti" closest to the surface shows up as sunspots), and recently we haven't been terribly good at predicting them. The solar minimum and maximum from the last solar cycle was not easily differentiable, and we are having more sunspots during the current solar minimum than we "should" be having. Furthermore, we haven't had modern scientific methods and records for long enough to show a real correlation between sunspot activity and ice ages, which is a pretty important thing to know. Even if we did have the data to show a correlation, we have no clue as to why the absence of dark patches on the Sun should make the Earth colder.

Prominences/Coronal Mass Ejections (CME's): The Sun isn't always just a big glowy ball of sunshine. It has bright, glowing loops of plasma that crackle and swirl between sunspots, like wiggly horseshoe magnets. These flow between oppositely-charged sunspots, much like electric current flows along a wire connecting the terminals of a battery. They vary in size (multiple Earth's can fit inside them, sometimes they stretch across half the Sun's diameter), and sometimes they can snap, lashing huge gouts of ionized plasma out at an unsuspecting patch of sky -- that we are sometimes occupying. These solar whip-cracks are known as coronal mass ejections, or CME's.

One of the awesome things about prominences are that they are large and therefore fairly easy to see through a solar telescope (NOTE: this is not a regular telescope, do not look at the sun through a normal telescope unless someone you trust with your ocular health has attached the proper accoutrements to do so, or your eyes will fry). Even if they aren't on the rim of the Sun from our vantage point, with a hydrogen-alpha filter you can still see them as snaky lines across the surface. Take a look at this amazing picture (click here), and think about the fact that each of those features is likely multiple Earths wide. It's beautiful, and terrifyingly violent, and intensely close.

Solar Flares: These are large bright spots in the solar atmosphere, when lots of electromagnetic energy is released and dissipated across the Sun. They occur near sunspots, which are highly active electromagnetic regions as we discussed earlier, so you could think of sunspots as being like storms, and flares being like lightning. However, a single solar flare can give off the equivalent energy release of millions of atomic bombs, so the scale is quite a bit larger than it is on Earth. NASA has a pretty good, not overly-technical article on them here (click here).

Hope you enjoyed the perusal of solar events! If you want to keep up on what's happening out in our neck of woods, I cannot recommend www.spaceweather.com highly enough. It's one of my favorite sites, and Dr. Phillips has forgotten scads more solar science than I will ever know. I'll return to this topic soon though, and then you'll get to hear my theories on our planet's future relationship with the Sun. Stay tuned!

Sun Science Part 2

Picking up where we left off...

The Earth: Most people learn about the layers of the Earth in middle school, but few remember much about the topic. The mantle is the most involved part of the Earth when discussing space weather. It is composed of many common metals, including large amounts of iron. Iron is important. These metals are in a semi-fluid state, where the heated portions near the core float up slowly, and the cooler metals nearer the crust sink to be re-heated. You can see this in a pot of water on your stove; were you to drop food colouring into a pot of water at a rolling boil, you would see the same pattern. Hot water moves up, it pushes surface water to the side, the cooler surface water sinks to start the cycle again (see here for a visual).

This circular motion is happening vertically under our feet all the time. Despite how slowly it happens (we suspect it takes tens or hundreds of millions of years for one convection cycle to complete), the motion of metal atoms against each other in the mantle causes an electromagnetic field around the planet.This field, called the magnetosphere, is one of the central players in space weather. Like the iron filings in this image (click here), the field curves in toward the magnetic poles of our planet. As we travel through space, it also compresses at our "front" and streams out behind us like an invisible comet's tail.

Why? Solar wind! Now next time (probably later tonight or tomorrow), we can finally get into solar activity and space weather!

Sun Science!

Ok, legitimate post! Yay break!

Today I present the only part of astronomy that I've followed religiously through my humanities phase: space weather!

What is space weather? It's the interactions between the Sun (and what it throws off) and the Earth (or other planets, but we're egocentric). Aurorae are the most famous visual manifestation of space weather, but there's a lot more to it. To understand the phenomena, we should start with a basic understanding of the composition of the Sun and our little home rock...

The Sun: this site (click here) gives a good, if slightly technical, description of the Sun's layers. As an overview, the Sun is essentially one vast ball of hydrogen gas (~91% H atoms), which is so immensely large that the hydrogen in the core gets crushed under its own "weight" into helium via nuclear fusion.* However, it's also got layers, like the Earth does. There's a large convective layer that mixes the extremely hot gas around the Sun's interior, and this creates electromagnetic currents. These currents run like strands through certain localities; they are not consistent throughout the Sun -- remember this, it's is important later. The outermost layer spins like a skin on a spherical pudding (insert typical physicist joke on spherical objects here). Much like the Earth's crust, it spins at a different speed from the lower layers; however, unlike the Earth's crust, the section near the equator spins once every 25 days, while the poles rotate once every 36 days. This causes something like friction at the regions where the speeds differ.

I'll carry on with the Earth next time; that's right, I'm leaving you with a cliff-hanger! 'Til next time, redshifted readers! And merry Christmas!


*N.B.: I put weight in quotes here, because weight and mass aren't the same thing. To use the age-old example, you weigh about 1/6 of your normal Earth weight on the Moon, but you certainly haven't shrunk -- in other words, your weight has changed but your mass hasn't. This is a function of the mass of the object you're standing on (or in, in the case of the hydrogen atoms in the Sun). In space, this becomes important, since gravity has a different magnitude for every star, planet, etc.

Frustration with the Red Planet

Finals are, in fact, over, so I can re-prioritize this. The first thing I did in catching up on the astronomy news I missed in the last week or two was checking up on the Mars rover.

I didn't want to sound like a spoiled child. But come on, there's been no real data released since that measly little announcement at the conference at the beginning of December! Curiosity's been "investigating" rocks, taking photos, sniffing the air, and digging around for over five months. It would be really nice to have heard more than "we didn't expect the wind to blow in this direction" and "oh look, more chlorates."

Short post tonight, just venting the frustration. I know they have to sift their own data for some time, but after this long I would've expected we'd at least have whatever new info they've gleaned from the first on-the-ground photos.

Kids in Astronomy

I was invited by a friend recently to hold an astronomy night for some kids. Now, I've never been known as a creative person, so where education types and elder sisters would be going nuts with tubes of glitter and marshmallows, I draw a blank. I know the things that make me excited about space, but the idea of that row of prematurely-jaded faces gives me the heebie-jeebies. I didn't understand those kids when I was their age; I understand them even less now.

So, I think about how I was when I was a pre-teen. The thing I wanted most was to have my intellect be considered the equal of any adult's. Just because I was in a pint-sized body, I reasoned, didn't mean that I couldn't grasp the concepts of quantum entanglement or multiple dimensions. One memory is particularly distinct. I was sitting on my bed, surrounded by my intro-level astronomy books. They were basically glorified picture-books, all bright colours and little text. I had a sheet of paper, with childish scrawling trying to piece together bits on black holes from each book. I was so frustrated. How could these authors introduce topics like singularities, and then just move on without explaining how they work, what we've seen, what we've calculated? It would be like killing Scheherazade on the 50th night. What's the point?

The bottom line is simple: children aren't stupid, they are untaught. A plethora of studies have shown that in so many topics, kids command flexibility and insight of mind that adults spend the rest of their lives trying to recreate. If anyone should be being fed our most complicated problems, it should be them. They have curiosity, intelligence, and imagination, and are unfettered by preconceptions about the so-called "laws" of the Universe.

So what am I going to tell these kids? I'm going to think of the "big concepts" that are supposed to be too much for their minds, and explain as much information as I can about them. I'm going to respect their brains, treat them as capable thinkers instead of cutesy factoid ingesters. Then I'm going to let them talk about it, stew in it, come up with solutions I bet would widen the eyes of any physicist. If we want to rehabilitate our nation's science education, this is how we need to start.

Brown Dwarves

I always feel like saying that is a slur, somehow...anyway, short post tonight (heading towards finals...who thought it was a good idea to hold regular exams a week before finals? Just cover the material in the final!) on brown dwarves.*

Brown dwarves are small objects that fill the rather broad size gap between planets and stars. Essentially failed stars, they start at around 12-15 Jupiter masses and go up to...well, the size of ignition, about 10% of the Sun's mass.

What's a failed star? It's an object that started collecting gas from a nebula (hydrogen, some helium maybe), and may even have created a disk of swirling material. Unfortunately, for whatever reason, it ran out of gas to accumulate. This means that its total mass was insufficient to crush the hydrogen atoms at its core into each other -- creating helium through nuclear fusion, and consequently kick-starting its life as a star. Instead, it just sits there like a largish ball of matter, quietly wiling away time.

Ok, that's why they're not stars, but what differentiates brown dwarves from rogue planets? Well, dwarves, ironically, are just too big. There are a few other differences, although if you look too closely, you'll find that astronomers are still a little fuzzy on the details.

Firstly, their pseudo-stellar-disk method of formation is similar to that of a star, not a typical planet. Many rogue planets are presumed to have been slingshot from an unstable orbit around a multi-star system. Not so with brown dwarves.

Secondly, they are hot gaseous bodies; most of our planets, and the other planets we've found outside our own solar system, are either terrestrial (can be hot or cold) or Jovian, which are typically cold. This is related to where they form: terrestrial bodies form closer to the star, with less chance of capturing or holding onto gases; gas giants form outside the "frost line," where most gases condense to liquids or ices.** Contrary to this, brown dwarves do not give off much light in the visible spectrum, if any, but they emit a good deal in the infrared (IR) spectrum. Compare the images from Jupiter in the IR spectrum here and an image of a brown dwarf binary system here.Other images are more dramatic, but clearly even from a far greater distance, the brown dwarves give off a great deal more infrared radiation.
 
Thirdly, planets differentiate if they're made out of more than one element (go look up diamond exoplanets, pretty awesome). Heavy metals like iron and nickel sink to the core, and lighter elements rise to the surface or atmosphere. Brown dwarves are just a ball of mush. Its gases may have been there since formation, or a small amount of hydrogen fusion may have occurred early in life; physicists are still arguing over the parameters.

So, brown dwarves. They're hard to detect and they make the border fuzzy between what seemed previously to be pretty nailed-down definitions. They aren't stars, and they aren't habitable. We can't quite seem to figure out what they're for, in the grand scheme of things. If I figure it out, I'll let you all know.




*Yes, dwarves; I hate American spelling.
**There are "hot Jupiters" being found by recent exoplanet searches, but the term is relative; they're still quite cold, and they are believed to have migrated inward towards their star from their original orbit outside the frost line.