This is the second and final part on the series of blogposts titled “The Science Behind the Solar Eclipse”. In this post, I will build upon the ideas and concepts discussed in Part I of the post to describe how solar eclipses occur. So I strongly recommend reading through it here. Solar eclipses occur because of the Moon blocks the Sun, as viewed from some point on Earth. As elucidated in Part I, due to the varying distance between the Earth and the Moon, the Moon may block the Sun in its entirety or a portion of it. Another way to think about this is the geometry of the Earth,…

An eclipse is defined as a total or partial obscuring of one astronomical body by another. For millennia, cultures all over the world have witnessed, marveled at, and feared eclipses. For residents of planet Earth, the two most interesting and important eclipses are of eclipses the Sun (Solar eclipse) and the Moon (Lunar Eclipse). A lunar eclipse occurs when Earth comes between the Sun and the Moon. The Moon shines brightly in the sky primarily because it reflects most of the light receives from the Sun. However, during the lunar eclipse, the Earth obstructs the path of light from the Sun to the Moon, leaving the Moon behind in its…

This is the final part of the three part series on Spaghettification where finally black holes come into the picture! Black Holes Black holes are regions of space(time) where gravity becomes is so strong that that not even light can escape. The size of this spherical region is specified by a radius called the Schwarzschild radius (in honor of the German physicist and astronomer Karl Schwarzschild). The radius of a black hole is proportional to it’s mass. For example: a black hole having the same mass as our Sun (what astronomers call 1 solar mass) is like a sphere having a Schwarzschild radius of 2.8 km. In comparison the sun’s…

This is second part in the series of posts about Spaghettification. In this part we go over the idea of how gravity squeezes objects. We will also briefly discuss how to make tidal forces stronger. Squeezing Now let’s rotate the rod so that it is oriented with both ends equally distant from the Earth, while the rod’s mid point is still located at a distance R from the Earth’s center. Unlike the case when the rod was vertical, here the Earth pulls at both these ends with an equal force directed towards the Earth’s center (white arrows in Figure 2). The force at the left end (point A) can be…

Can black holes make spaghetti? Like Obama, black holes would reply ‘Yes we can’! To top that off they can make spaghetti out of anything – using their ‘gravitational machinery’. In this three part series we will see how black holes employ gravity to do so! Before we go exploring black hole’s ‘spaghetti skills’, in part I, first let us look closer to home, at our very own Earth’s ‘spaghetti skills’ and its connection to the concept of tidal forces.  Gravity and Tidal Force Let’s begin with the familiar. Earth produces a gravitational field by the virtue of its mass, and objects immersed in this field feel a gravitational force.…

In today’s post I will talk about Compton scattering – a physical process by which light and matter interact. Interestingly, this process is responsible for colouring our sky and also for generating electromagnetic radiation from the most energetic phenomena in the universe. A Brief History This phenomenon was first discovered by Arthur H. Compton in 1923, for which he won the Nobel Prize in 1927. This process was also an important evidence of the particle nature of light, i.e, it proved that light (or electromagnetic radiation) exhibits particle like behaviour. In other words, if light only behaved like waves then the energy lost by light during Compton scattering could not…

Fantastic Beasts (and where to find them) Most galaxies on our universe seem to harbor, at their center, the amazing beast known as a supermassive black hole (to know more about black holes see my previous post here). What do we mean by word supermassive? Astronomers compare the mass of most objects in the universe with the mass of the most massive object in our vicinity, i.e., our sun. Supermassive black holes are millions to billions of times more massive than our sun. To put it simply, millions of our suns together would weigh as much as these beasts! For a nice visualization see this link. Light from the vicinity of…

Hello readers! I am Atul Chhotray, a post-doctoral researcher in Sera’s group. I am a theoretical / numerical astrophysicist, which means I employ the laws of physics / computers to understand and explain the workings of the universe. I have been fascinated by black holes since time immemorial – and in this post I will talk about them a bit, and jets. A Very Brief Introduction to Black Holes Black holes are regions of space where the gravity is so strong that not even light (which travels at the fastest possible speed in the universe) can escape it. For an Earthly example, imagine that you want to go into space.…