On Earth, one can indirectly find what the structure of inside the planet is by measuring the waves created by an earthquake. The Earth’s interior, having layers with different compositions, will refract and reflect those waves, and by measuring the wave all over the Earth, what can make a reasonable assumption as to what the Earth is like inside it. Unfortunately, we can’t exactly place seismographs in other planets. In the case of Saturn, though, there is a structure you can measure which will indirectly tell us what is going on inside the planet. It is the rings, which it turns out that while its shape is predominantly affected by Saturn’s moons, they alone don’t account for all the waves on it. The planet itself affects the rings, and one of the findings is that the inside of the planet is sloshing around. More details is in the link above.
I didn’t think I would live to see the day, but they did it. Obviously I have underestimated way too much the capabilities of our current technology ^_^ . The planets did have the benefit of being far away from their parents star, and they are huge, but still, it is quiet the accomplishment. I also found a science paper (which I found thanks to this) about the spectroscopy of the planets, if you want to read it (beware, not for your average joe). Yeah, not much to say about this one, the links will tell you everything.
There is exciting news for extrasolar planet enthusiasts. A planet smaller than Mercury has been discovered around a regular star, one similar to the sun. This is another excellent discovery done with the already very productive space telescope Kepler. The discovery was helped by the fact that the planet rotated very close to the star. After all, an astronomer needs to detect at least three signals in order to confirm a planet, and finding a planet that comes in front of the star from Earth’s view is more probable the closer it is. The latter is important because Kepler finds planets by looking at a dip in the star’s brightness caused by the plane moving in front of it.
Now, is it the smallest planet discovered ever? Possibly not, it is probably one of the planets of a pulsar system. But it kind of isn’t fair, since pulsars have a very regular rotation period, which one can measure because it sends out jets of lights that crosses the Earth everytime it rotates. One can use discrepancies in the rotational period to detect planets that are very small in mass. For the transit method, though, this is very good. It means we are well on our way to discovering rocky planets in habitable zones. We just need to observe a lot longer. Three years for an Earth sized object that goes around in one year. And we get even more variety in our discoveries, instead of just gas giants and superearths, which have been dominating discoveries because finding bigger things is easier.
Kepler’s first law states an object orbits another object under a gravitational pull in a conic section orbit. If the orbit is closed, it is an ellipse. It also turns out to be really hard to prove. You either have to use calculus and differential equations, or use geometry with lines and stuff and know well the properties of the ellipse. Either way, you have to set up the problems in creative ways. In this post, I would like to collect all the ways Kepler’s first law can be derived. I have always found it annoying how scattered the proofs were, and I would like to leave this behind for anyone who is itching to find out how Newton’s laws implies elliptical orbit and vice versa.
For a newbie, the best proof out there is in my opinion Feynman’s geometric proof. While it is still complicated, it is not as hard as the other proofs to understand. You don’t have to know anything too complicated except for some of the properties of the ellipse, and get used to the methods of geometry. It is also great for its clarity, unlike Newton’s geometric proof. Newton’s proof is convoluted and use really complicated geometry, but if you would like to know how the master himself did it, there it is.
The most common derivation is the differential equation approach. It is the standard textbook approach, and if you know something about calculus and differential equations, it is easier to swallow. Then there is the more complicated version which takes account of the fact that two move around a center of mass, instead of one around the other.
My favorite version, though, is the one that uses the Laplace-Runge-Lenz vector. Its derivation is elegantly simple, following directly from the approach. In the other differential equation method, you have to find the acceleration in terms of polar coordinates and then do a creative substitution that makes them end up as a simple second order differential equation. This one is somewhat less convoluted than that, and once you get the vector, you are only one step away from Kepler’s first law. In The Mechanical Universe and Beyond, video 22 titled The Kepler Problem uses this derivation.
Finally, I know there is the one that uses the complex function. Unfortunately, I can’t find it online. It is contained in this book, though.
If anyone knows of other alternatives, I can post it here.
Secondly, and this is the best of all news, they have discovered over a thousand candidates of stars harboring planets. Over the next few years, expect the number of planets discovered to increase dramatically.
hat tip: badastronomy and io9
Recently, I don’t know how long ago, though, the Zoo Universe project, which tries to involve citizens in helping out the professional astronomers sort through data, have added a new project to its list. It is called Planet Hunters. What it does is, it gathers the light curve data of stars (basically, the star’s brightness through time) from the space telescope Kepler and allows us to look at them. The basic premise is that stars have planets (well, duh), and some of those stars might have planets that orbit right in front of the star from our point of view. Those planets block some of the light from the star, thereby dimming it. By looking at the change in brightness in the curve, mainly the dipping of brightness at certain moments in time, one can detect planets, as shown in the picture below:
Of course, things aren’t as simple as that. As you will find out from checking out the web page and the tutorial, data is full of noise. The team behind this project, though, believe that because the human brain is so effective at noticing patterns, that we might be better at detecting these dips in between all of the noise than the machines. Maybe.
Anyways, go ahead and try! Who knows, maybe you might discover a planet.
This is so last year, but I want to post this for the interest of general education. The reason I am posting it this late is because I forgot, but now that I remembered, here it is. The reason I am posting this is that in astronomy, the search for extrasolar planet is more relevant than ever. Better and better technologies like the Kepler space telescope are being used to probe the vast expanses of our galaxy in search of habitable planets. The e-mail interview below is one I did for my English research report for college, but I believe you may find it of benefit too. The topic is on the method of searching extrasolar planets and some of the discoveries astronomers have made. The one being interviewed is Christine Pulliam, public affairs specialist from the Harvard-Smithsonian Center for Astrophysics, to whom I am very thankful for spending some of her probably precious time answering my request and allowing me to post this. I hope you enjoy it: Read the rest of this entry »
This is my first review of the science show Bad Universe. I missed the pilot, so I am reviewing episode 2. That is too bad because the first episode was about asteroid impact, which I think is cooler and has a much better ground in reality than tonight’s episode: Alien Attack. Here is a teaser, which the host of the show himself, which the badastronomer Phil Plait was generous to post on his own blog:
So, the first thing I want to comment on is the host Phil Plait. And just as I expected, he was awesome. The explanations were simple, as expected, but the delivery of them is really good, with neat graphics and visuals backing them up. Also, he injects a nice amount of humor. I thought the random cutout to the steak scene was quiet funny while explaining that most living things on Earth uses sunpower. Mostly, though, I think it is his personality and enthusiasm which makes the show enjoyable to watch.
Today’s episode was kind of cheesy, especially the initial invasion scene. That’s okay, though. The theme of the episode was alien attacks. I really liked the flying saucers lasers destroying things scene, which were very reminsicent of Independence Day. The robot, though, was very lame, with its very crummy design. By the way, since this is my first time watching the show, I would like to compliment the comic book style presentation. It is very unique, and I especially love it when they cartoonize the various people Phil Plait is meeting with. Also, the comic book style presentation was really effective when it came to presenting the infectious bacteria from outer space. A live action shot would have probably shown some boring blur of bodies covered with sheets, or other sorts of boring stock footages that these kind of shows like to bring up. And while some of the annoying repetition, like the freaking alien footages, was here in this show, I think that the show’s presentational style kind of balanced it.
As an example of the comic book style presentation, look at the intro of the latter half of this clip:
The science itself was mostly good. The show was mostly devoted to answering the probability that alien life could come on our planet. So naturally, the first thing that was presented was the Drake equation, which estimates the probability intelligent life might exist in the galaxy. I thought it had a really neat presentation. It was basically a walkthrough of each variable along with the snazzy graphic showing the letters in a floating 3d look. At the end, he explained that it was all a guess, which I am glad he did. Although I don’t think he should have stuck with 20. Maybe he should have mentioned a range because what the viewers could take from that is that the number is a fact.
Afterwards, Phil showed what it would take for aliens to travel the vast interstellar distances. Basically, one would have to accelerate so much for so long that one would probably throw up one’s stomach out after the first few days in the trip, as Phil’s nauseated look showed after having endured over 4g’s of force in the jet plane. Although this brings up a question. Can’t they just accelerate in spurt? Since space is pure vacumn, there is no air friction that slows it down. So according to Newton’s first law, once you speed up, you just keep going and going. Of course, then the spacecraft would have to slow down, and as you see, the whole enterprise sounds like a mess. Unfortunately, the show didn’t mention the ultimate obstacle of space faring aliens: the speed of light, the speed at which no matter shall travel. At a certain point, no matter how much energy you dump into the ship, it would only get closer to the speed of light, never get there. But then, it is a 45 minute show, and there is only so many things you can put in there, so all is forgiven.
My two favorite segments came afterwards. The first one was an experiment trying to show whether e. colis could survive an impact if they came riding on an asteroid into Earth. They did it by putting a solution of bacterias inside a metal ball and shooting it in a long air gun towards a pile of sand. The poor blobs didn’t make it, unfortunately. So, the ruling of alien bacterias arriving on Earth is almost nil. While a lot of bacteria can survive space and radiation, whether they can survive being sent into space after an impact in another planet, and then surviving the crash on Earth is a whole another story. The other cool part was the cave exploration. They were making the point that life doesn’t have to be like the way we know it, so an extreme planet could support life. They made their point by citing extremophiles, which are bacterias that survive extreme conditions. In the cave, there were no sunlight, yet bacterias thrived by metabolizing minerals on rocks. They managed to scrape some and show them under a microscope. Very cool.
As for the martian rock thing, it was kind of meh. While I agree that the chance of Mars having had life back in the really old days (as in billions of years ago), I don’t think the patterns on the rock is it. Granted, I was impressed with the patterns on the rock, since I didn’t know how weird rocks were microscopically. But it reminds me too much of the previous life on martian meteorite hype in the 90′s. Well, I think it was a hype. If anyone out there is an astronomer, what do you think? As he says in the end, we need more serious study on this subject.
Finally, there was the replicating robot kills everything scenario at the end. While the scenario is science fiction, I have got to admit, it is quiet compelling and really cool. It is my favorite scenario, and no, I am not sadistic (c’mon, they are replicating robots!). He placed this as one of the more probable one because these are machines, and they can endure the coldness and harshness of space, and grab resources to make more of themselves. In the end, he summarizes the whole thing this way:
“We just don’t know.”
And in the end, that is the best answer there is, and the best way to end the program.
(hat tip from Universe Today for everything below)
This is an exciting time for planetary discoveries. Not only has the Kepler mission been launched, a whole batch of super Earths to neptune planets are being discovered. That is a far cry from a few years ago, when most planets that were being discovered were giant sized gas planets that were the likes of Saturn and Jupiter. Many of them were found extremely close to their star, closer than Mercury is to the sun. In a way, giant planet discoveries are still the case, but smaller and smaller planets are becoming easier to discover.
Take the case of these two star system discoveriesz: one by ESO with at least 5 planets, and at most 7, most of them Neptune sized. The smallest planet could possibly be 1.4 times the mass of the Earth. The one by Kepler, by using a system in which it detects the dimming of a star by the planets orbiting in front of it, discovered a system of two Saturn sized planets and one possible 1.5 Earth mass planet. At this rate, an Earth sized planet discovery is possible within a few years, although note, both super Earths are not confirmed yet. But still, one can hope.
You know what the most unfortunate aspect of this is, though? The distance in space is so large that not even a space probe could be sent in those places to investigate and snap pictures (my favorite part of a planetary survey). Even if it were possible, it would take hundreds, if not, thousands of years for the probe to get there, and send back the data. Oh, and remember, depending on which stars you are talking about, it takes light around decades to centuries to reach the Earth from those places. Light is too slow, darn it!
If you want to keep up with the planet discoveries, you should get this iphone exoplanet catalogue app. Otherwise, you might go to the next best thing, which is this catalogue, by the same creator of the app.
Ok, Sylvester McCoy’s era of Doctor Who reference aside, this post will be about a horrible process of death via black hole called spaghettification. That’s right, spaghettification is actually the official word for what happens to stuff that goes in a black hole.
This post has been inspired by this Let’s Play Mario Galaxy video by chuggaconroy, who by the way, makes great videogame walkthrough videos. In it, he tries to explain what spaghettification is, starting from 7:15:
Although his explanation of spaghettification sounds awesome, it is incorrect. Of course, he is not a physics expert, so he gets major parts of the process wrong. That’s okay, though. Not everyone can be a physicist. I am not one either, but I understand it enough. If someone out there knows better, feel free to correct me. If you feel like my explanation is too much, then you can just watch the fun explanation of dismemberment by Neil de Grasse Tyson below. Read the rest of this entry »