### Estimating the radius of the Sun - The medieval way

I still don't quite understand the whole process but I'll talk about what I do! But if you don't want to listen to me talk, you can go ahead and read my reference. And before we measure the radius of the Sun, we need to measure the distance to the Sun. Or atleast that's how it was done in the olden days.

So, to start, Halley envisioned a way to estimate the distance to the Sun, using the transit of Venus across the Sun. Depending on what latitude one observes from, the time taken by Venus to cross the Sun is different. If one records the time taken and has an estimate of the drift velocity of Venus, in radians per sec, one can estimate the distance between the two paths Venus takes across the Sun's surface. How to estimate the drift velocity of Venus you ask? Well, we know that it takes the Earth 365 days to complete 360 degrees and that it takes Venus 242 days to do the same. We can therefore estimate the relative velocity with which Venus drifts away or comes towards us. And using this, one can estimate the distance between Earth and Venus (this is where I am stuck!).

Coming to the distance between the Sun and the Earth, it can be written as the sum of the distance between Sun and Venus and Venus and Earth. The distance between Sun and Venus was estimated to be 0.72 times that of the distance between the Sun and the Earth. How you ask? Kepler's third law of course, which relates the time taken for a celestial body to complete one full revolution to it's distance from the center of revolution. We know the time it takes for the Earth to go around the Sun and astronomers were also able to measure how long it takes Venus to go around the Sun (one more thing I need to look up!). Using this, they were able to relate the distance between the Sun and the Earth and the Earth and Venus. Okay, I need to be more quantitative than qualitative. Sigh...

But well, you understand how I can estimate the radius of the Sun once we have an estimate of the distance to the Sun, because we know that the angular size of the Sun is approximately half a degree.

On a serious note, this is getting interesting. I need to make proper notes of this, after I make sense of it. While I was searching for how astronomers estimated the distance to the Sun, I came across similar estimates and methods used for the rest of the planets. It's all geometry, trigonometry and sheer brilliance! I never realized that the lower rungs of the cosmic distance ladder were this interesting. Actually, I thought the lowest rung was stellar parallax, but then even to reach that step, we need the value of One Astronomical Unit i.e the distance between the Sun and the Earth!

Apart from the link I provided at the beginning of this post, there were a few other articles I found online that were of (a bit of) help. Some of them are 1, 2, 3, 4, 5, 6.

### Animation using GNUPlot

Animation using GNUPlotI've been trying to create an animation depicting a quasar spectrum moving across the 5 SDSS pass bands with respect to redshift. It is important to visualise what emission lines are moving in and out of bands to be able to understand the color-redshift plots and the changes in it.
I've tried doing this using the animate function in matplotlib, python but i wasn't able to make it work - meaning i worked on it for a couple of days and then i gave up, not having found solutions for my problems on the internet.
And then i came across this site, where the gunn-peterson trough and the lyman alpha forest have been depicted - in a beautiful manner. And this got me interested in using js and d3 to do the animations and make it dynamic - using sliders etc.
In the meanwhile, i thought i'd look up and see if there was a way to create animations in gnuplot and whoopdedoo, what do i find but nirvana!

In the image, you see 5 static curves and one dynam…

### on MOOCs.

For those of you who don't know, MOOC stands for Massively Open Online Course.

The internet is an awesome thing. It's making education free for all. Well, mostly free. But it's surprising at the width and depth of courses being offered online. And it looks like they are also having an impact on students, especially those from universities that are not top ranked. Students in all parts of the world can now get a first class education experience, thanks to courses offered by Stanford, MIT, Caltech, etc.

I'm talking about MOOCs because one of my new year resolutions is to take online courses, atleast 2 per semester (6 months). And I've chosen the following two courses on edX - Analyzing Big Data with Microsoft R Server and Data Science Essentials for now. I looked at courses on Coursera but I couldn't find any which was worthy and free. There are a lot more MOOC providers out there but let's start here. And I feel like the two courses are relevant to where I …

### On programmers.

I just watched this brilliant keynote today. It's a commentary on Programmers and the software development industry/ecosystem as a whole.

I am not going to give you a tl;dr version of the talk because it is a talk that I believe everyone should watch, that everyone should learn from. Instead, I am going to give my own parallel-ish views on programmers and programming.
As pointed out in the talk, there are mythical creatures in the software development industry who are revered as gods. Guido Van Rossum, the creator of Python, was given the title Benevolent Dictator For Life (BDFL). People flock around the creators of popular languages or libraries. They are god-like to most programmers and are treated like gods. By which, I mean to say, we assume they don't have flaws. That they are infallible. That they are perfect.
And alongside this belief in the infallibility of these Gods, we believe that they were born programmers. That programming is something that people are born wit…