Not a PhD

A "Year" on a planet is the time it takes to go around the Sun. None of the planets in the Solar System fit the question, though, so I'll just treat it as a hypothetical planet, around a hypothetical star. In 5 months, if the planet goes around the star 10 times, it means that a year would be just 12.5 years long. Now, it is not possible to directly calculate the distance of the planet from the star from this, or the mass of the planet. All we know that the planet's centripetal force (from rotation) should balance the gravitational pull for it to be in a stable orbit. If the star is similar to the Sun in size, the planet will have to be: 1. Much smaller than the Earth, and very close to the star 2. At least as large as the Earth, but farther from the star, moving much faster than the Earth. When it comes to age, gravity and exposure to radiation are both major factors. So, if you're farther, you will probably age even less than the 5 months. But if you...

This question can be answered in two ways - the first, what we literally cannot see, that is, the part of the Universe that is beyond the scope of our eyes. Second, the part of the Universe that we do not know about at all, even using all our senses and all the instruments at our disposal.  Our eyes are sensors of electromagnetic radiation, that is, light. As Nature is very efficient, our eyes detect only the right amount of the Sun's light to protect ourselves from predators and find food. Unfortunately, this means that we do not see a lot of the light that is around, such as X-Rays, UV-rays, IR rays, Radio waves, Microwaves, etc. This image shows how much we don't see - the same object photographed in six different frequency ranges.  Today there are telescopes that look at every part of the electromagnetic spectrum. However, there are not enough to look at every part of the sky, so quite a lot of the Universe remains unseen.  The part of the Universe that we...

The Hubble Space Telescope (HST) was launched in 1990 aboard the Space Shuttle Discovery. It was the beginning of a revolution in Astronomy, as it could see beyond the veil of the atmosphere. It was not the first space telescope -  working telescopes have been used in space as early as 1968. However, Hubble was larger than the previous telescopes, and could capture visible light as well as near-infrared and near-ultraviolet frequencies. The telescope has contributed vastly to human knowledge, not to mention photographs beyond human imagination. Here are some of the most spectacular: The Hubble Extreme Deep Field Light can travel only at the rate of 3 lakh kilometers per second. This implies that if an object is so far that it takes light a year to reach us, we will see it as it was a year back. This is an especially exciting concept in astronomy - telescopes actually show you the past, and the more powerful the telescope, the more you see into the past. The Hubble E...

The currently accepted theory for the beginning of the Universe is the Big Bang Theory. According to this theory, the whole Universe expanded from a single point, around 13.8 billion years ago. The moment when the expansion started is known as the Big Bang, and this theory was just one of the competing theories till it was proved experimentally. How exactly do you prove that something happened at the beginning of the Universe? Let's start with a quick review of the events. What we call the Big Bang is a gravitational singularity. A singularity is a point where the laws of Physics no longer apply - which means that we know practically nothing about it. The singularity was in a state of very high density, pressure and temperature. These were not on the scales of anything we can imagine within the scope of human experience. For some reason, this singularity started expanding and cooling rapidly. This was followed by a phase (actually several phases, but explaining those ...

"What do you do?" "I'm an amateur astronomer. I teach astronomy." "So, you're a PhD?" This conversation happens just about every time I meet a new person. It's understandable. And yeah, I do want to do a PhD. But the fact is, you don't need to have a PhD to love the Universe, to explore it, or teach it. Hence, this blog. It is a celebration of two of my loves, Astronomy and teaching. I will be posting articles I love, essays I write, speeches I give, and primarily, answer questions about the Universe in a way that's simple but accurate.