Gurudev Observatory

Questions - Science

 Which is the biggest Moon of Pluto?

It's Charon, with a diameter of 1212 km (some sources say 1207 km):
Charon is so big, compared with Pluto (diameter 2370 km), that the couple Pluto-Charon is almost a double (dwarf) planet, with its barycenter outside Pluto.
Pluto has 4 other satellites, much smaller than Charon: Nix, Hydra, Kerberos and Styx.
jld-Ir.Jean-Luc L.J.Dighaye ,President,EurAstro Association

Ham school ke bachcho ek sath vota kai Se kare-Unknown sender

 You schools students my cast your votes by clicking multiple vote link at

What is an astronomical year which is coming this year on 15 November starting from 3 pm?This was related topic in an article printed in a ewspaper declared by NASA. -Himani Mehul Dave 

( 1 ) I have to say that I had not heard about this phenomenon until I looked up information about it as a result of the question.  Having read a number of items that refer to the 15 day blackout that is supposed to occur starting at 3:00 AM on on the15th of November, I have to agree with some of the articles that have stated that the prediction is false.  The prediction seems to be that the blackout period has something to do with the interaction of Jupiter and Venus, but I have seen no explanation of what this interaction could be nor can I think of any interaction that would cause such a thing.  As a scientist I need some sort of logical explanation of how such a thing could occur and I see no evidence of that.  There was also a statement that the head of NASA submitted a 1000 page report about the blackout to the White House.  I am a retired NASA scientist and I think I would have heard something about this if it were real, but I knew nothing about it until I started to look at some of the websites talking about this.  Thus, I tend to believe web information such as this site ( which discusses some of the strange stories that have appeared concerning NASA from false news outlets. -Dr.Jim Thieman - NASA Scientist/Data Systems Manager (retired) 
( 2 ) According to certain sources, the world will experience 15 days of total darkness starting 15 November 2015:
NASA is cited as the source of such "news".
However, NASA never issued such a statement, and the above-mentioned source is dubious, to say the least:
So, no need to worry - the announced darkness will not occur, it's just a false rumour.-Ir.Jean-Luc L.J.Dighaye ,President,EurAstro Association


What are neutron stars and how they come into existence -Nachiketa Mishra ,Age 10 years,Merrut ,India

( 1 ) You probably know that stars are balls of very hot gas or plasma (gas that is electrically charged) that give off intense light indicating that they are indeed very hot.  Our Sun is an example of such a star.  The gas is held together in a ball-like shape because of gravity, the force that pulls all the gas toward the center of the star.  The heat of the star and the escaping light makes the gas want to move around and bounce off the other particles and that tends to push the gas away from the center.  The pushing from the heat outward and the pull of gravity inward balance each other and so most stars maintain their shape and appear to us to remain the same over very long periods of time, billions of years.  Some stars, however. that have a lot more gas than our Sun become unstable and the force of gravity causes them to shrink to the point where they explode in what is called the supernova state.  After they explode, what is left of the star shrinks way down to be as small as about 12 to 13 km across but weighing still more than the Sun.  The star is composed almost entirely of neutrons which are the neutral particles at the center of atoms, this it is a neutron star.  The material that makes up this neutron star is so dense that one teaspoon weighs much more than a battleship.  -Dr.Jim Thieman, Radio Jove, NASA,
(2) "A neutron star is a type of  stellar remnant that can result from the gravitational collapse of a massive star . Neutron stars are the densest and smallest stars known to exist in the cosmos ; with a radius of only about 12–13 km (7 mi), they can have a mass of about two times that of the Sun.They are composed composed entirely of neutrons with slightly larger mass than protons.-Ir.Jean-Luc L.J.Dighaye ,President,EurAstro Association


Sir what is different between HST & JWST.AND JWST will find a new universe? what you think...Harshil Patel,Bharuch,India


The major differences of the JWST compared with the HST are its larger mirror (thus allowing higher resolution and sensitivity), its emphasis on infrared observations, and its higher orbit centred on the Lagrangian point L2 (

Surely, the JWST will not discover another Universe, but plenty of new things in ours, such as our distant, early Universe; the penetration of obscuring dust and gas; and the observation of dim, cooler objects. It will play a key role in the detection of exoplanets i.e. planets orbiting other stars than our Sun.-Ir.Jean-Luc L.J.Dighaye ,President,EurAstro Association

It is said that energy can never be created nor destroyed. Then what happens to light and heat energy of stars engulfed by a massive black hole? - Gyanesh

All the mass of the star which falls into a black hole increases the mass of the black hole - there is no clash with conservation principles. - Dr. Rathnasree Nandivada, Director, Planetarium, Delhi

I want to know about 4th dimension time and 5th dimension gravitational force and relation with black hole. - Prashantmahan Balubalu

We received so many vision & thoughts about your question from our expert panel..But conclusion is that till date the relation has not been proved by science but that doesn't means the end.Future is bright.Let us hope for some new invention about the phenomena.You are most well come to ask questions. - DDPurohit


sir you, tell me that how to devided stars name in alpha,beta,gama,delta...etc,,,,,like in urasa major some stars name is merak (beta UMa)-HIP 53910,,,phad (gama UMa) - HIP 58001,,,megrez ( delta UMa ) - HIP 59774,,,dubhe ( alpha UMa)- HIP 54061 A...etc AND here HIP means???? - Harshil Patel, 12th Science, Bharuch

A good article on the Bayer nomenclature, assigning Greek letters to a constellation's bright stars, is found here:
Usually, in a constellation, alpha is the brightest star, followed by beta, gamma etc. but there are exceptions, a notable one being Ursa Major, where bright stars are designated from one end (alpha = Dubhe) to the other (eta = Alkaid).
HIP numbers refer to the catalog of stars provided by the Hipparcos astrometry satellite operated from 1989 to 1993, see any of
Note: I personally worked in the calibration, in a vacuum tank of the Astrophysical Institute of Liege, Belgium, of the Hipparcos satellite from 1986 to 1988.--Ir.Jean-Luc L.J.Dighaye ,President,EurAstro Association

While in space astronauts can get taller but at the same time their hearts gets smaller. Why?- Kushal U. Vyas, Vadodara, Gujarat.

To me, it's a question of lack of gravity. Due to it, the body is no longer compressed in the direction of gravity, as it is on Earth, so it tends to get taller. Meanwhile, the heart no longer has to pump blood upwards - as on Earth, thus the blood circulation is eased, to the point that the heart might atrophy. - Ir. Jean-Luc L. J. Dighaye, President, EurAstro Association

Sometimes we see an inverted rainbow. Why? - Unknown Sender

(1) Actually it is the Circumzenithal arc, CZA which is the rare & most beautiful halos. It fled from its watery origins & wrapped improbably about the zenith. - DDPurohit

(2) To me, inverted rainbow is a second arc, concentric to the first one, but with the colours reversed, i.e. red inside, blue outside. It stems from multiple reflections in the raindrops. - Ir. Jean-Luc L.J. Dighaye, President, EurAstro Association

Why do nucleons exhibit strong nuclear force? Why does it become repulsive when the separation between them is reduced? - Unknown Sender

The nuclear force is the force between two or more nucleons which is responsible for binding protons and neutrons into atomic nuclei. At very short distances of less than 0.7 fm, it becomes repulsive and is responsible for the physical size of nuclei, since the nucleons can come no closer than the force allows.It plays a very important and crucial role in the existence of our Universe.- Ir. Jean-Luc L.J. Dighaye, President, EurAstro Association

I believe as I read in a book titled "god particle" every human being is a cosmos. Well, all of we humans are able to perceive the visible universe and the invisible cosmos. But there is a fundamental cosmos within us. This cosmos MAY HAVE TO BE UNDERSTOOD better to be connected with the outer universe. By doing so, we MAY be able to enjoy nature much more and understand it well. What is your view sir on this subject of connections in nature? - Abhilash Chintan, post graduate student, Coimbtore, India

(1) The Higgs Boson was sometimes called "the particle of God", but our understanding of the Universe comes though the laws of Physics not metaphysics.

The connection with Nature comes with patient, scientific observation. I hope you can enjoy it sooner or later. - Ir.Jean-Luc L. J. Dighaye, President, EurAstro Association

(2) Our ancient books say that "Yat pinde, tat brahmande" meaning that our body is a tiny part of the cosmos but is filled with cosmos. This means that the cosmos passes through us, it survives in us and, at the end, we will be mixed with the cosmos. Our sages knew this fact so they invented amazing formulas, inventions etc. by using the incredible intellectuals and not any physical infrastructure which happened only due to the presence of the cosmos in thier body. - DDPurohit

I understand every human is composed of the cosmos as you said me. This cosmos is an incredibly noble thing if we are able to realize how we are connected to nature around us always. I doubt that maybe all life in the universe is made of the same cosmos? - Abilash, Coimbatore

The laws of physics and chemistry are valid through the whole of the Universe. So, barring other life-generating chemistries (e.g. based on silicon), which are less promising than those based on the elements C, H, O and N like on the present Earth, we can say yes, all life in the Universe is based on the same elements. -Ir. Jean-Luc L. J. Dighaye, President, EurAstro Association

(1) In the past two decades, there has been a dramatic rise in mental health problems. Is this related to the sunspot cycle? If yes, what is NASA's stand on the impact of the 11-year cycle on human behaviour? - unknown sender

(2) Can gravitational waves of sun has any mental or physical effects on humans?- Kushal .U. Vyas,Vadodara,Gujarat.

(3) Is there any research, which proves, the effect of space activities ( related to Planets/ stars / sun / moon / eclipses / etc.) on human beings. The effect, in term of physical, mental, emotional disturbances or improvements. - Hitesh Joshi ,S.O,Bhabha Atomic Research Center,Mumbai


(1) Until now science has concentrate on the impact of space weather on satellites, the power grid, astronauts life, GPS etc. and not on other aspects. But I strongly believed, and my research database shows, that strong and massive changes in space weather, due to solar storms larger than M Class and with Beta-Gama-Delta field, CME with the speed more than 1000 km/seconds with some other criteria, do have an effect on climate and human / animal ( living things) behaviour. - DDPurohit

(2) There are those who have studied this and believe there is a link. Here is a web site with links to various papers on the subject Solar activity: mental, physical and emotional health - Bill & Melinda Lord, SARA, USA

(3)There have been many studies to try to determine if mental or physical health problems correlate with the sunspot cycle. So far, no correlation has been found. There have also been studies trying to see if the current global warming is at all related to the Sun and/or the sunspot cycle. No correlation has been found. In fact, activity on the Sun during the last cycle has been very low. Yet global warming has been proceeding very rapidly.- Dr.Deborah Scherrer ,Director Stanford Solar Center ,USA

Who is the creator of the Universe? - Siril Patel (6th SemB.SCwith Physics from V.P. & R.P.T.P. Science College, V.V.Nagar)

You should decide what you want to know my child, and ask a proper question. I certainly agree with your vision about vedas and its powerful knowledge.They are the ocean of knowledge. If you want to know about the creator of the Universe then on science and spiritual science base we can tell that it is nothing but energy who not only has created the Universe but is also responsible for existence, operation and destruction of the cosmos. Every thing is filled up with it and is zero without it. You are most welcome to ask more questions with your friends. - DDPurohit

It is said that the energy emitted by a black hole is more than that of the energy absorbed. So how it is possible? - Kushal. U. Vyas, Vadodara, Gujarat.

As per Hawking Theory, Hawking radiation reduces the mass and the energy of the black hole and is therefore is also known asblack hole evaporation. Because of this, black holes that lose more mass than they gain through other means are expected to shrink and ultimately vanish. - DDPurohit

Hindu mythological stories say that God created the whole world (universe) but science says that it is due to the Big Bang and other comological reactions, so which is correct? - Kushal. U. Vyas, Vadodara, Gujarat.

Both concepts represent the same theory with different words. Hindu mythology tells the complete story of the evolution of the Universe but in Sanskrit and in poetry. The Big Bang and Ekoham Bahusyami are one and the same. - DDPurohit

Both our body and the universe are made of the cosmos, but our life span is short compared to the universe, why it this so? - Kushal. U. Vyas, Vadodara, Gujarat.

Every object in the cosmos has a fixed life span depending on its mass, volume and fuel consumption. The same thing happen to our body also, as our body is small compare to big celestial objects and we consume fuel if form of breath, vitamins, pran shakti and vital energy, so our life span is small compare to the universe. - DDPurohit


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