Installing numpy on ubuntu 20.04

Check your version of Python

python3 --version
sudo apt-get update

The easiest way to install numpy is to install Pip, which is sort of a package manager that helps you install packages in Python.

Let’s install Pip first and then numpy.

sudo apt install python3-pip
pip3 install numpy

Let’s verify numpy

pip3 show numpy

This will show you which version of numpy is installed and more.

Now, let’s import the numpy package

Go to python


Once in python, you can import the new package and add an alias for it (in the example below it is np):

import numpy as np

That’s it, folks!


How to install iraf

IRAF – Image Reduction and Analysis Facility, is a product of NOAO. It has been widely used in the astronomical community to reduce data in the form of images and spectra.

IRAF works best in UNIX distribution.

  1. Before setting out to install IRAF in your device, find out if your OS is 64 bit or 34 bit.

You can do this by entering the following commands :

$ sudo -s #( specify your user password)

$ uname -m # this will tell you if its 64 bit or 32 bit

2. Download the IRAF package

$ wget

3. This package ‘ iraf-2.16.1-2021.06.14.tar.gz ‘ can be found in Downloads of your file explorer.

Copy it to your desktop, home or wherever you want IRAF to work from

Extract it there

this sequence can be done manually or using commands

$ mv iraf-2.16.1-2021.06.14.tar.gz /home

$ tar -xyz iraf-2.16.1-2021.06.14.tar.gz

$ mv /home/iraf-2.16.1-2021.06.14 /home/iraf

Additionally to the tar file, a C compiler, the “make” program, flex, and some development packages are required.

4. Depending on your OS, do the following steps:

On Debian and its derivatives (Ubuntu, Mint, Devuan, Raspbian etc.):

$ sudo apt install gcc make flex
$ sudo apt install libcurl4-openssl-dev libexpat-dev libreadline-dev

On Fedora and its derivatives (Redhat, Scientific Linux etc.)

$ sudo dnf install gcc make perl flex
$ sudo dnf install libcurl-devel expat-devel readline-devel

On MacOS X, you need to have the XCode tools installed to build from source. If you haven’t, you can install them with:

$ xcode-select --install

5. Install

Make sure you are in the folder where the iraf package is installed which in our case is the folder iraf at home

$ cd /home/iraf
$ ./install 		# execute the install script

6. The script will prompt you for the path to the default image directory, the cache directory and the binary files directory. Usually, you can everywhere use the default settings when asked from the install script.

Just click enter every time


Include the binary files directory in your PATH before proceeding to the <make> step. In BASH this can be done with the command:

$ export PATH=/path/to/iraf/bin/:$PATH

where </path/to/iraf/bin/> is the binary files path specified to the install script.

8. Now you can configure the system for the proper architecture and build:

$ make <arch>
$ make sysgen 2>&1 | tee build.log

#this last step takes a while, this is where your iraf software tree is being built.

<arch> should be replaced by the appropriate keyword according to the following table

<arch>Operating systemSupported CPU types
linux64Linux 64 bitx86_64, arm64, mips64, ppc64, riscv64, alpha
linuxLinux 32 biti386, x32, arm, mips
macos64macOS 64 bitarm64
macintelmacOS 64 bitx86_64
macosxmacOS 32 biti386
freebsd64FreeBSD 64 bitx86_64
freebsdFreeBSD 32 biti386, arm
hurdGNU HURD 32 biti386

9. Test to make sure that the IRAF build works fine. To execute the tests, run:

$ ./test/run_tests

10. Open a new terminal window and type ‘cl’ to launch IRAF

$ cl

Note : besides the iraf folder, there is a file called build.log. do not delete this, it contains your whole IRAF build.

Time taken

1. To install IRAF

Sept 26 2021 , 2 PM – 2.30 PM

2. Compile an installation manual for IRAF

Sept 26,2021 , 9.30 pm – 9.50 pm

The science girl series

A script by Johina Maria


Science Girl

Nikki – Scene 1
Manu- Scene 2
Nami – Scene 3
Laks – Scene 4
Jo- Scene 5

Narrator :

There are two kinds of magic in this world. One that pulls rabbits out of hats and the other that makes us believe in a kind of idealism , to grow up and change the world , to be a superhero, to use our abilities for the good of the world, to take knowledge and wisdom into our hands and make the world better with them. Which one is better? The second, I’d say.
And with that, let me tell you the wondrous tale of the Science girl.


Setting : It’s a bright beautiful day. Nikki, is wandering about the ground and finally decides to sit under a tree and enjoy her book.

( She opens her book and starts reading)

Her Cousin, Paru, comes by.

Paru : Don’t sit there! A coconut could fall on your head!

Nikki : Go away. Let me read my book.

Paru : What are you reading anyway? Don’t you know anything about gravitational force?

Nikki : Oh, you are the know-it- all! Let me read now. Go away.

P: Don’t you know? There is a force that pulls every object on earth towards the earth. Newton came upon the idea when an apple fell on his head, sitting under an apple tree. But you are sitting under a coconut tree. Go sit somewhere else.

(A coconut falls near Nikki almost missing her)

Nikki : Whew! I should have listened to you! It almost fell on my head. So, this is gravitational force.

Paru : Yep. Gravity is why we things that go up fall down. It’s why we are even standing on the surface of the earth.

Nikki : Really? Wait. Is there no gravity on the moon? Is that why astronauts in cartoons fly away? Because there is no gravity?

Paru : No, no.. The moon also has gravity. But the gravity there is less. That is why they fly around. You can fly around on earth too . You see, gravitational force is an interaction between two objects that have mass. On earth, we feel the force more because the earth has mass and the astronaut has mass. The moon however, has less mass than the earth. So, if you are on the moon, you would feel gravity less and be able to fly around like Superman!

Nikki : Wow! Wait, Is that gravity we feel when we go up an elevator?

Paru : You got it! But Newton’s third law works there. I’ll tell you!

Nikki giggles

Nikki : That’s enough for today, Science girl!

Paru smirks

Scene 2

It’s the summer holidays and Meenu finally wants to go cycling. She hadn’t used her cycle in a long long time and now she wants to!

She gets her cycle out and tries to move it, but the pedals won’t move and the chain is stuck and a little bit rusty

Meenu : How do I go cycling on this thing?! Arghh, Why won’t it move!

She tries to pull and poke the chain. But it won’t move the pedal!

Paru : Meenu, What are you doing over there?

Meenu : Getting this thing to move!

She pokes and pulls at the chain again.

M : Why won’t it move?

P : You know why? It’s because of frictional force.

M : Okayyyyy. Can we get rid of this frictional force and get it cycling?

P : Yep!. See, frictional force is a force that opposes motion. You haven’t used this cycle at all in a while, right?

M : Yeah

P : So, when you left it outside without using it, it caught rust. And now, the chain won’t move because it has more friction. The chain is connected to the pedals here, see. So the pedals won’t move and that is why your cycle is sitting there like a statue.

M : Okay. Wait.. Is that why our gate was difficult to open last week? Because of friction?

P : Yeah!

M : I saw aunty putting oil on it. And it was smooth.

P : That’s what we are going to do too. Let’s clean this up and put some oil on it

M : And I can finally ride it! yay! Science girl to the rescue!

Scene 3

Meenu is trying to create a fire by rubbing rocks together. Science girl stumbles upon her.

P: HI Meenu! What are you doing?

M: I am going to make a fire.

M: Do you know how early men created fire? By rubbing rocks together.

P : Yeah! Do you remember friction, Meenu ?

M : Yeah. That’s what creates the fire you know here.I read up all about it.

M : When the rocks rub up against each other, there is friction and see, its hot because friction has an heating effect. But this is taking a long time to catch fire.

P : oh! That’s because this is not the kind of stone that would produce fire. You might get a spark, that’s all.

N : You couldn’t have said that sooner!

Scene 4

Paru and Laks are hanging out.

P : Let me show you some magic, Laks!

L : Okay! What do I do?

P : Take a scale and some bits of paper.

L : Okie. I’ve got it.

P : Now rub the scale on your head and bring it to the bits of paper.

The paper stands up and is attracted towards the scale.

L : Wow! How does this work?

P: When you rubbed the scale on your head, it ended up with more electrons and became negatively charged. And when you brought the scale closer to the paper, it attracted the paper which didn’t have as many electrons and so is positively charged. Positive attracts negative and negative attracts positive.

L : Is that why my flyaway hairs stand up after brushing?

P : Exactly!

L : That was a neat trick, Science girl!

Scene 5

Setting : It’s a dark and stormy night. There is lightning and thunder and the girls are on each of their beds, a little scared with each bolt of lightning flashing through the window.

Jo : I can hear the wind howling. There is another flash. And now the thunder will roar!
Do you think this will go on the whole night?

P : Maybe so, Maybe not. Do you know why thunder comes after the lightning?

Jo : I think it has to do with speed. Maybe the speed of light is more than sound. That’s probably why we see the flashes first and then hear the thunder later.

P : Exactly. Light has a speed of 300 million metres per second but sound only has 340 metre per second. Do you know how lighting comes about though

Jo : No, go on, science girl. I know you want to explain!

P : Up in the sky, air molecules, water droplets and even ice crystals in thunder clouds rub against each other creating positive and negative charges. Then they attract each other. Sometimes, this attractive force is so strong that they push through the air to get to each other and you have lightning!

Jo : So it’s electrostatic force at action, pulling the charges together to make lightning. That is beautiful, you know.

P : Yep. There are so many forces out there ruling over nature. It’s beautiful to know how they work in things we do every day, even when we are at play, at work or just sitting simply. That is why I love science. If you know the right things, you can take them and use them to solve your everyday problems and make the world better for everyone. It’s amazing. That’s why I want to do Science.

The End.

A magical day at the Vainu Bappu Observatory

In a 100-acre forest land in the Javedi hills of the Vellore district of Tamil Nadu, stretches out the Vainu Bappu Observatory, a beautiful place to behold. I spent the day roaming about the beautiful stretch of land, climbing trees and enjoying a brisk walk through the forests.

Hidden in plain sight

The Vainu Bappu Telescope here was the largest telescope in Asia until the ARIES telescope launched in 2016.

I sat in awe in a corner, cross-legged, on the floor of the gigantic room that housed the telescope. Too scared to step out on the catwalk, I stood there looking out at the picturesque scenery that lay in my vision, the bright beautiful flowers, the giant trees, and the hills that combed out far ahead. Evening came, and the hundred acres of forest was engulfed in darkness and I found myself lying on the prickly grass staring at the multitude of stars above me and a soothing calm growing inside me. I spotted an artificial satellite blinking through the sky, they are a common occurrence, it seems. I could also make out the different constellations that adorned the beautiful sky, Orion, the hunter; the Big Dipper.


It was one of the most beautiful days of my life. I lived near the beach and I had spent many a night under the starry sky picture that no artist could paint. There were more stars in the sky than I have ever had seen. It still bewilders me that when you are looking at the multitude of stars out there, you are looking at their past, you are looking at what happened plenty of light-years away.

The observatory is open to the public during some days of the week. It’s not a place that many would visit but to any photographers who happen upon this post, it’s your paradise, a ticket to many perfect shots.


A bright burst of orange red


Vampire Stars

In the cold dead of the night, even in the scurry of a hundred street lights, an orange star shines brightly above the belt, on the Hunter’s right shoulder. A red supergiant on the verge of exploding into a supernova, Betelgeuse is a true enigma.

Betelgeuse is twenty times larger than our sun, so massive that in the sun’s place, it could very well swallow up the earth. Such a massive star should spin slowly as when size increases, the rotation rate should decrease. But that is not the case with the red giant, a 2016 study says. It’ spinning faster than it actually should. Why? The study speculates that a 100 thousand years ago, Betelgeuse may have gobbled up its companion star about the size of our sun, transferring the angular momentum of the companion star to the giant and thus securing its ultra-fast rotation. Betelgeuse may well be, a vampire star.

Stars don’t live alone. They live in clusters. They are born from the same clouds of gas and dust. They live and age together in the same cluster. Some of them share their gravitational field with a companion star, near or far away from them and they exist as binary systems. They rotate and traverse their orbit and sometimes when in a straight line with their companion, eclipse the other. It’s a beautiful relationship.

Artist’s impression of a vampire star and its companion star. Credit: ESO/L. Calçada/S.E. de Mink

In some of these binary pairs, where one orbits the other or in a shared gravitational field where they orbit close together, there is a possibility that these two stars could merge. There is also the chance of the low mass companion star pulling off materials from the surface of the larger star, rejuvenating itself, smiling blue and younger defying age. The low mass star is dubbed a vampire star. This may have what happened a 100,000 years ago when Betelgeuse became a red star or not. For all we know now, Betelgeuse is a single star.

A soul tie fashions between two stars in a binary system and the low mass star strips off material from the surface of its companion star. The low mass star and its companion now become hotter, younger versions of themselves. One sacrifice to make the other better. Though infamously called as a vampire star and its victim, the stars tell a tale of true friendship, a tale of the oneness of two kindred souls.

Why science writing? & Published! #1

Now, THAT is a topic tag!

If you read me, that is,  if you read my blog and muse upon the words that echo my thoughts, you would know how passionate I am about writing.

People schedule things that they want to learn and want to do, but I have an intrinsic clock inside me that makes me write and read. I yearn to read and I yearn to write, no push/no motivation needed. It gives me such joy.

I stumbled upon science writing and then, the wheels in my brain started going round and round every time I looked out to nature, up the sky, at the beach, and everywhere else. Thoughts became words and penciled in a paper, they became something. A work of art, maybe not perfect, but an original.

I published my first science article outside of my blog and I am ecstatic. It’s in a newsletter by the Dubai Astronomy Group.

So here it is! Enjoy and leave me ur comments 🙂





How would space look like if gravity never existed?

There would be no space if gravity didn’t exist. The earth would probably break into chunks and disintegrate. There would be no earth!


The jazzy bright horizon

Evening comes and with it brings the promise of beauty undaunted. Striking bold hues adorn the sky when the sun goes for a dip in the sea. No one is born as beautiful as she, draped in her iridescent brick-red soft flowing saree.

When you stand mesmerized, gazing at the coruscating kaleidoscope of colors, you cannot help but wonder why the sun breaks out in multi-hues every sunrise and sunset.

Scattering is a process in which forms of radiation like light, sound, etc are deviated from their straight path to many different directions due to the collision of the light particle with another particle. When sunlight passes through clouds, light scatters in many different directions. Water molecules in the sky after a rain scatter light into VIBGYOR and we have the rainbow!

Now, scattering depends on both the size of the particle and the wavelength of light. Less the wavelength, the more it is scattered. Thus, the short wavelength blue light is scattered much more and it reaches our eyes, this is why the sky is blue.

At dusk and dawn, when the sun is lower, the light that travels has to battle with more molecules which scatter the blue and violet (also has short wavelength) away from our line of sight. Meanwhile, the other colors make it to their destination, our eyes and we see red, orange, rose gold and the magic of the sky.

Stars, the storytellers #1


Gazing at the stars above, do you know that you are actually looking at their past? Light from the sun takes about 8 minutes and 20 seconds to reach the earth. So, when you are looking at the sun, the sunspots that you see, the eruptions and the wild mechanics of the solar wind are about 8 minutes and 20 seconds old. It takes about 4 years for light to travel from the Alpha Centauri (the nearest star to earth) to earth. So when you see what you see it’s the past. You are looking at what happened four years before from now.

Suppose there is another planet out there teeming with intelligent life, 10,00,000 light years from us when they look at us, they are not gonna see the clutter of buildings or advanced human life. They are gonna see Tyrannosaurus, Spinosaurus and Giganotosaurus, and the dense coniferous jungles, scrublands and riparian forests.

On a clear starry night, when you look out at the gazillions of stars above, think about this and revel in the mystery that is our universe.

Image Credit: Kerry-Ann Lecky Hepburn