Timekeeping in Astronomy

"Captian's log, stardate 1513.1. Our position: Orbiting planet M-113. Onboard the Enterprise: Mr. Spock temporarily in command. On the planet: the ruins of an ancient and long dead civilization. Ship surgeon McCoy and myself are now beaming down to the planet's surface. Our mission: routine medical examination of archaeologist Robert Crater and his wife, Nancy. Routine, but for the fact that Nancy Crater is that one woman in Dr. McCoy's past."

 - Opening of Star Trek: The Original Series, Season 1, Episode 1; "The Man Trap"

If you're curious like me, you'd have noticed that the Captain's log from Star Trek used some form of strange new system of measuring time. What does stardate 1513.1 represent? It turns out, it doesn't really mean much. It was just another way of making the show look futuristic. From Wikipedia:

"We invented "Stardate" to avoid continually mentioning Star Trek's century (actually, about two hundred years from now), and getting into arguments about whether this or that would have developed by then. Pick any combination of four numbers plus a percentage point and use it as your story's stardate."

But interestingly, the convention used by astronomers to keep time is very similar sounding to the stardate system seen in Star Trek. Astronomers use what is called a Julian Date whenever the time and date of a measurement needs to be mentioned.

Calendars have a long and messy history. The calendar system that is in use around the world today is called the Gregorian Calendar. People only started using this calendar in the late 1500s. Before that there was something called the Julian Calendar which was introduced by Julius Caesar in 45 BC. These are two big calendars. But there were also a lot of other calendars in use by different countries and cultures. A look at calendar systems in wikipedia shows a mind boggling and confusing list of widely varying systems. Some are similar, some are wildly incompatible. Also, due to the fact that the time taken by the earth to go around the sun is not an exact integer multiple of a day, errors inevitably arise when measuring time in years or months. Astronomers needed a standardized method of referring to time for astronomical observations. This was the motivation behind the adoption of the Julian Date.

A Julian Day Number is an integer that represents the number of days that have passed since 1st January 4713 BC in the proleptic Julian Calendar or 24th November 4714 BC in the proleptic Gregorian Calendar. (NOTE: A preleptic calendar is a calendar obtained by extending a calendar system backwards in time to date before AD 4)

The Julian Date of any point in time is the Julian Day Number of the previous day along with a decimal number that represents the fraction of the next day that has passed.

For example, the 1st of January, 2014 1800 hrs is represented by a Julian Date of $2456659.25$

I hope everyone has a wonderful time celebrating another complete revolution of the Earth around the Sun. An exciting year lies ahead!

Richard Feynman on Education

Feynman, a robust and awe-inspiring physicist who won the Nobel Prize for his work on Quantum Electrodynamics, once went as a visiting Professor to one of the universities in Rio, Brazil. He was able to get an inside view of how the system worked there, and with characteristic wit delivers a talk pointing to the many flaws - the over emphasis on memorization, the lack of emphasis on actual hands on experience and empirical evidence, and how the system is loaded against the people who truly do have an idea of what it means to be a scientist - and how they sadly end up discouraged and instead conform to the prevailing "wisdom". In the following excerpt from "Surely You're Joking, Mr. Feynman!", he gives a first hand account of how the event transpired and eventually ended.

---

In regard to education in Brazil, I had a very interesting experience. I was teaching a group of students who would ultimately become teachers, since at that time there were not many opportunities in Brazil for a highly trained person in science. These students had already had many courses, and this was to be their most advanced course in electricity and magnetism – Maxwell’s equations, and so on.

The university was located in various office buildings throughout the city, and the course I taught met in a building which overlooked the bay.

I discovered a very strange phenomenon: I could ask a question, which the students would answer immediately. But the next time I would ask the question – the same subject, and the same question, as far as I could tell – they couldn’t answer it at all! For instance, one time I was talking about polarized light, and I gave them all some strips of polaroid.

Polaroid passes only light whose electric vector is in a certain direction, so I explained how you could tell which way the light is polarized from whether the polaroid is dark or light.

We first took two strips of polaroid and rotated them until they let the most light through. From doing that we could tell that the two strips were now admitting light polarized in the same direction – what passed through one piece of polaroid could also pass through the other. But then I asked them how one could tell the absolute direction of polarization, for a single piece of polaroid.

They hadn’t any idea.

The Beginner's Guide to the Galaxy

So you're interested in space and you're bored of watching documentaries on Nat Geo or the Discovery Channel. And you want something to do during the power cuts. Don't panic, here's our beginner's guide to astronomy.

So, shall we take that telescope?
Not so fast! That's one misconception that many people have. You don't need to have a telescope to begin astronomy. I'm not kidding. The sky is a calendar and there is so much you can learn with just limited tools! Once you're familiar with spotting basics objects like planets, Orion nebula and constellations, you can buy binoculars and telescopes. if you have a good budget, go for buying good quality "reflective" telescopes.

Now what?
There's tons of stuff that you can see with your eyes - satellites, planets like Mars, Jupiter, Venus, Saturn; the ISS (the international space station), the Pleiades star cluster (a...cluster of stars, duh), meteors and even the Orion Nebula (A collection of gas visible to the naked eye) . Stellarium is a good software that will help you find these objects () If you have an android, download Google sky map.

Start out getting familiar with the sky. First try to notice a very prominent constellation like Ursa Major or Orion the Hunter. You'll realize that most constellations barely resemble what they're supposed to represent :/ After that, it should be easy to spot the other objects using relative positions.

www.heavens-above.com will help you to spot satellites and the ISS, just make sure you set the home location to Trichy or Wherever You Live Town. Many 'iridium flares'  - bright reflections from a certain type of satellite - would be visible during the evening, it is quite fun to watch them swimming slowly across the sky. Once you have registered and entered your location, you can click the links for iridium flares and the ISS to see when they are visible.

Cool machi! What's next?
Just have an open mind. Remember, we're all amateurs here when it comes to the Universe. Expand your knowledge and try to understand what the stuff really means and absorb all the vastness and beauty. As the astronomer Carl Sagan once said, "Somewhere, something incredible is waiting to be known." His book and TV series, Cosmos is also a must watch, along with practically anything by Neil DeGrasse Tyson.The Bad astronomy blog  is a good place to check out recent developments in astronomy.

Glossary:
Magnitude: Scale used to measure brightness of celestial objects. It's a log scale, like the pH scale. Bizzarely, the lower the magnitude, the brighter the object is. Venus, the third brightest in the sky has a magnitude of about -4 or thereabouts, whereas a star with mag 5.5 is just visible to the naked eye. Stars with higher magnitudes are dim and can only be seen through telescopes or other devices.
Altitude: Angle of elevation in the sky, with ground level at 0 and zenith at 90 degrees. the Pole Star's alt is about 10 degrees in Trichy.
Azimuth: The direction of the object, with north at zero, east at 90, south-east at 135 degrees and so on.

Have a good journey!

Image Processing in Astronomy

"Having finished chopping up his roots, Harry bent low over his book again. It was really very  irritating, having to try and decipher the directions under all the stupid scribbles of the previous owner, who for some reason had taken issue with the order to cut up the Sopophorous Bean and had written in the alternative instruction:

Crush with flat side of silver dagger, releases juice better than cutting.

......(several sentences later).......

Harry crushed his bean with the flat side of the dagger. To his astonishment, it immediately exuded so much juice he was amazed the shriveled bean could have held it all. "

-J.K Rowling in Harry Potter and the Half Blood Prince

Basic sciences like physics have come so far that huge, monstrous, expensive beasts like the Large Hadron Collider are required to push the boundaries of scientific knowledge. The days were the lone astronomer spent long, peaceful hours staring through the objective lens in the remarkable solitude of the mountains are long gone. Today, very little astronomy is done by people physically looking through the telescope. Instead, we have gigantic tubes (or conduits to the cosmos as Neil deGrasse Tyson puts it) and state of the art, cryogenically cooled sensors take the place of the human eye. These sensors are hundreds of times more sensitive and quite a bit less prone to error and fatigue than the human eye.

In astronomy, the raw data we get from the telescope is Harry's Sopophorous Bean and and the flat side of the silver dagger represents the various image processing techniques and algorithms astronomers have in their arsenal. These algorithms and techniques can often make the data exude such a surprising amount of information that you'd be amazed that the weird looking stream of numbers could have held it all. Image processing is used in most parts of astronomy today. From basic observations of pulsars to extremely complicated things like radio interferometry image processing is a ubiquitous tool in astronomy. It is what is used to turn the grainy, ugly raw data we get from telescopes into the enchantingly beautiful images of the cosmos that people use as desktop wallpapers.

In this post I'm going to talk a bit about an image processing algorithm known as DRIZZLE. The DRIZZLE algorithm is special because it can be used quite easily by amateur astronomers to get good looking photographs of celestial objects.

The algorithm was developed by Andrew Fruchter and Richard Hook and is used when the low resolution of the CCD sensor results in the image being undersampled. The algorithm takes several images of the same portion of the sky with slight shifts applied to telescope aligns the stars to account for the shift and adds all the images together. This combined image has more information that any of the individual images and can result in a final image that seems to have a higher resolution than the actual sensor resolution. It's a bit like human vision. What your left eye sees is almost exactly the same as what your right eye sees except for a slight shift. Your brain is able to combine these two shifted images together to get information about depth which cannot be obtained from either of the individual images.

Here is an image from Wikipedia that shows the difference between a raw image and an image produced by using the DRIZZLE algorithm.

On the left a single 2400s F814W WF2 image taken from the HST archive. On the right, the drizzled combination of twelve such images, each taken at a different dither position.

If you're interested in learning more about Drizzle, you can go to this website. It has a more detailed but still accessible explanation of $DRIZZLE$ with more examples to help you visualize how the algorithm does what it does.

This is just the tip of the iceberg when it comes to image processing. I'll be blogging about more awesome image processing stuff over the next couple of years.

Until next time! :)

The Science of Gravity

The first time I watched the film Gravity, I admit I was a bit disappointed - probably because all the hype in the movie critics circle led me to have really astronomical (ahem) expectations for the film. It was the second time I watched without any accompanying expectations that the full impact of Gravity hit me like high speed debris from space. It was one of the most visually arresting movies ever made, and the special effects are near realistic. Go watch Gravity in a good theater with 3D. (I cannot believe I'm saying this, but the 3D actually works in the movie). You'll be dazzled.

The Plot (lots of spoilers):
Rookie astronaut Dr.Ryan Stone (Sandra Bullock) is on a mission to service the Hubble Space Telescope along with her mentor Matt Kowalsky (George Clooney). Meanwhile, a Russian satellite is shot down, creating a cloud of debris that moves at dangerously high velocities. The Space Shuttle is quickly destroyed by the debris, and Dr. Stone has to find a way to return to the planet below. The two protagonists reach the International Space Station, only to find that re-entry is impossible with the Soyuz. The debris which revolves around the earth faster than a speeding bullet returns every 90 minutes to its starting point - an orbital time bomb. Matt dies while in the process of entering the Space Station, leaving Ryan to fend for herself and to find an escape using the Chinese space station Tiangong.

The Good Stuff:
While there are many goof ups in the realism of the movie, it is much more faithful to reality and science than most other sci fi movies. There are a lot of things which the movie got right, and here are a couple of good things I noticed which are based on the truth:

• The Earth. My God, the first shot in which they show the Earth was really beautiful. It was also a nice touch to show things with no particular up and down - it took me a while to realize that we were seeing South America tilted sideways. The first 20 minutes are a single shot, with the camera moving freely and the focus moving back and forth between the characters, the earth and the space shuttle.

• The debris problem is based on a real thing, the cloud moving at high speeds will cause a cascade effect as it destroys more debris which make matters worse. This is called the Kessler's syndrome. Something like this is also the basis for the anime Planetes.

• The stars were accurate! It's not a big thing, but I actually saw real constellations like Scorpio, Orion and Pleaides pass by in the background. (Yes, I'm a big geek I know) Many other movies just make do with a random star background for the night sky (although, the movie fell prey to this during a pivotal scene when Ryan Stone is disconnected from the space shuttle arm and keeps spinning as the camera pans to reveal the center of the Milky Way....and random stars.)
• The space station, shuttle and the Soyuz capsule were captured effectively as well! Check out this video of Sunita William's tour of the ISS in which she shows the Soyuz capsule - the controls and the interiors look recognizably familiar to the ones shown in the movie. There were comments by members from the space program on reddit.com claiming that they got even the right kind of pencils floating around in the ISS! 

I don't want to believe

"I don't want to believe, I want to know." 
- Carl Sagan

It was a clear winter evening of November, not a regular thing I know, but this just happens to be one. The wind was still tingly cold. As I chugged down some hot coffee, I looked up at the sky to notice birds flying in a "V-Shape". Distorted the shape was, but the sight stirred my emotions. Why do they fly in a certain shape? Did someone teach them? Clearly birds couldn't have cooked up this gimmick all by themselves?

We humans are story telling and pattern seeking animals- we tend to delude ourselves when our emotions are stirred. We have a distinct memory of the instances where a pop tune rings in our head and suddenly a friend sings it! Clearly this was no co-incidence?. We tend to, in that emotional stir, forget that our head resonates with non-sense all the time. We don't keep a count of all the days where the tune was persistent but not the co-incidence. It's like football, the goal keeper is commented when the opposition scores a goal whilst all the goals he saved are not discussed as rigorously.

Every phenomenon is beautiful in it's own way. Some for example- Sunrise, convection of fluids and frank reed sources have "Patterns" that can be recognized by us Humans. Other's like- Brownian motion, Dislocations inside a Crystal do not! It's beauty and the truth associated with it are not determined by our convenience.

We evolved from primates and hence have an affinity towards dominance hierarchy-

Let us go back to the "V- formation of the birds". The coffee, the sky and my mood were brilliant that day(not a regular thing I know), now add to that some sort of bliss and we have a recepie for self deception. I can for instance, tell my self that some "Father figure" harnessing all knowledge and wisdom told the birds to make a "V" and not any other alphabet like a "Q" or "O" because he wants us to remember that he was born of a Virgin.

Or I can contend with facts, that this "V- formation" makes an aerodynamic shape, enabling the birds to travel long distances. Surely the bird in the front takes the maximum air-drag, but it makes flight a lot easier to all the others. If we carefully watch their flight we would indeed notice that, after a period of time the bird in the front "takes a break" and the next "important one" comes in the front. Something like our political campaign, the candidate "taking the heat" from criminal allegations, "steps back from the front" until it dies down and he's ready to compete for the next tenure (No I'm not sub-consciously thinking of Narendra Modi).

Read more about V-formation:http://en.wikipedia.org/wiki/V_formation

Knowing rather than hopeless rationalization or believing, helps build scientific temper. It increases the competitive edge in a world arranged on science. It also surges the awe,wonder and most importantly teaches us humility- a trait which helps us to understand our place in the universe and gives a sense of "Spiritual connection".

Consider now a scientist working on a new theory to explain high temperature superconductivity. Not an easy thing to do really, he has to theorize something on a scale of atoms and electrons, a very unfriendly scale to humans. It is tiring for him to analyse, imagine and relate his findings from the "Sister experiments". So he spends himself in the theory, he romanticizes it. All his social conversations at dinner tables now become awful since he is occupied with his own strife. Everything happening around him- movie songs, news titles and random family issues, remind him about his work.

He realizes now that he is now in a relation, a love affair with his own theory! Our scientist finally wraps up his whole business with the cold outside world and goes into a happy isolated affair with his theory. As the moment of truth approaches, when he puts his theory to experimental scrutiny, the numbers and results don't match-up. Now he has to wash his mind of that mishap, he has to drain all the negativity, his partner broke up!

Our subjective reality, no matter how sweet our rationalization of the phenomenon is to us, is not a measure of truth! Science lay's down facts with a straight face! Science is far away from knowing everything and it's clearly not going to be easy. But this is the best thing we ever had! We should try our best to add to the body of knowledge and reduce the error margin as generations pass. We also have to tirelessly and wirelessly promote scientific thought and leave scant room for delusions and ignorance.

                                                                                                                                                 -Cherry

Introduction!

We're Nakshatra. We are legion. We are starstuff. Expect us.

*cue menacing Star Wars - imperial march music*

Ahem, sorry for that bit of weirdness. So, about us. We are basically a bunch of jobless college students looking to learn the subtle science and exact art of amateur astronomy, and in the process get to know how science works. Most of our lives, we lived through a system that prioritized memorization over methods, that only made students to learn the dull facts and definitions as though that were all that is to science. Well, you can't blame the "system", if there is such a thing. They did the best they can under the circumstances, if we were in their place perhaps we could have come up with nothing better under the constraints they must have faced. That, however, does not change the fact that there is something severely lacking in how science is taught and understood by society, colleges and schools. Minds are not trash cans to be filled but candles to be ignited. We don't wait for the constraints to relax or the "system" (whatever that is) to reform itself to start a revolution in thinking.

We are "the astronomy and science club of NIT Trichy," or at least that is what our pages and posters proclaim. We conduct regular - cough - occasional stargazing sessions to look at and study the planets, Messier Objects and the moon. We also conduct talks on relevant science issues sometimes. Most of the time we just do nothing and make elaborate, far fetched plans of conducting events, workshops etc.

But we're new, starting out. Our operation is small, but there is lot of room for aggressive expansion. (Okay, I'll stop with the cultural references now.)

Knowledge and understanding have been cloistered long enough. it is time we experience a renaissance that had long been asleep.