SCIENCE CAPSULES

      Our sun is a ball of fire.  Its flares  are extending to  thousands of kilometers.  It is in the middle life and produces such a enormous energy.  It is a small star and all the stars  are similar to our sun.       When a star is living it produces light and heat energy through nuclear fusion.  That is, by combining hydrogen atoms into helium atoms.  When the star runs out of the nuclear fuel, it will die.  During the death of a big star, its outer shell will blast off with such a brightness that it will be visible throughout the galaxy even in daytime.  This phenomenon is called 'supernova'. Next, star's inner core will get compressed due to gravity.  That is, star will collapse under its own weight.  It will collapse into a mathematical point called " gravitational singularity ".  All the mass is concentrated in that point.  Hence it will have zero volume, infinite ...

Is earth a lonely planet?  Is there any other civilization in our milky way galaxy ?  These questions are answered by Drake equation .  First let us see the variables in the equation. 1. N# - There are roughly 100 billion stars in milky way  galaxy. 2. FP - 20%  to 50% have planetary system. 3. NE- 1 to 5 planets of each star have the capability to sustain life. 4. FL - 0% to 100% of the planets have the capacity to support and evolve life. 5. FI -  In 0 % to 100 % of planets, the intelligent life evolves. 6. FC - 10% to 20% of intelligent life try to communicate. 7. FL - How long the intelligent life survive and communicate? It is tough to guess.  We are communicating using radio waves for last 100 years only.  N - If we multiply all the above factors ,  we may get the probable number of intelligent and communicating civilization in our galaxy. N = N#*FP*NE*FL*FI*FC*FL Let us guess the minimum values, substitute in the equa...

        The calendar mainly based on the motions of celestial bodies.    We know the time taken by the earth to go round the sun once is taken as one year.  We also know the time for the earth to spin is taken as a day.  It happens to be 365+ days in a year.  That is why, a circle is divided into 360 degrees.       Moon takes roughly 29+ days to go round the earth.  Hence 30 days average is taken as the month.  The moon revolves around the earth 12 times a year.        Seven days makes a week.  Because only seven heavenly objects were known then.  Hence the week days were named after them. Sun - Sunday, moon - Monday, mars - Tuesday, mercury - Wednesday, Jupiter - Thursday, Venus - Friday, Saturn - Saturday.      In the past, sundials (measuring time using shadow) were used to measure daytime.  It had 12 equal marks.  So we have "12 hours  day a...

    Cut the trunk of a age old tree.  We can see number of rings in the cross section.  Each ring is formed during a year.  The count of rings gives the age of tree.      Earth rock and meteorites that has fallen on the earth has a composition of potassium-40 and organ-40.  Potassium is the radioactive element.  It emits radiation and decays into organ.   Radioactivity never stops .  The original potassium atoms are slowly converted into organ.  By counting the number of radioactive potassium atoms and stable organ atoms, one can estimate the age of rock using this formula. N = n*e^(-R*T) N - number of radioactive atoms at present (potassium) n- Number of radioactive atoms during the formation of        rock(potassium + organ) R - Radioactive constant of potassium T - Age , time elapsed since the formation of rock. e - Maths constant      This is called radiometric...

   Newton law says, every object in the universe attract every other object by gravitational force.  Scientist Cavendish proved that two lead balls attract each other using torsion balance experiment.  He also measured the universal gravitational constant G using that experiment.  The gravitational force is the weakest one but a long range force.       Gravitational force is responsible for the formation of galaxies, stars and planets.  It keeps planets revolving around the sun and satellites around the planets.      On launching, a rocket must reach the speed of 11.2 km/sec.  Then only it can pierce out of earth's gravitational field(escape velocity).  Even if the speed is slightly less, it will fall back to the earth due to gravity.      Once out of the gravitational field, everything start to float.  Astronaut can sleep in any position since there is no gravity and consequent...

      Scientist Focault made a pendulum using 200 foot long wire and 61 kg bob.  He conducted an experiment using this pendulum in Paris.  This large pendulum can swing for an hour before getting damped.  He attached a pin at the bottom of the bob.  The pin drew line in the wet sand spread on the floor.  After an hour of swinging, focault observed, the line drawn on the sand rotated (tilted) by an angle of 11.25 degrees.  How this happens?  Let us examine.      When the heavy pendulum swings, the plane of swinging or the path of oscillation cannot get altered.  While the pendulum swings strictly in one direction, the floor of the earth slowly rotates .  Hence the direction of the line drawn by the pin on the floor slowly changes(tilts).  After an hour, there is a observable change in the direction of the drawn line.      Focault measured the speed of rotation of the earth accurately by t...

  Einstein predicted that heavy astronomical object can bend light like a lens due to gravity.  Years later, Eddington proved this and then Einstein was shot into fame.      We know, stars cannot be photographed during the day.  So Eddington chose a total solar eclipse day ,  a proper place and photographed stars' light passing by the sun.  The same stars were photographed in the night when the sun is not present near the path of star light.  Both the photos were superimposed.  A shift in the positions of the same star were observed in the overlapped photographs.  The shift proves that the sun's heavy gravity attracts and bends the star light.      When a very big star dies, it collapses, shrinks, becomes a massive object and develops enormous gravity.  This gravity attracts and obsorbes all the light.  Hence we call this object as a black hole .      Since massive astronomical body ...

    Moon is under the gravitational influence of the earth.  Hence it revolves around the earth. It completes one revolution around the earth in about 28 days(one month).  It also spins about itself in the same time . So naturally, it shows the same face to the earth always.  One can easily walk on the moon's surface and follow the sunset or sunrise since it spins slowly compared to the earth(24 hours).  Consequently the lunar day is nearly 28 earth days long.(14 days night; 14 days day)   While the earth orbits the sun, the earth carries the moon along with it.      The moon is the only astronomical object close to the earth.  Light takes 1.28 seconds to travel from moon to the earth.      Moon is the smaller body and hence it has small gravity. Your weight will be greatly reduced on the moon.      When a torch light is switched on the moon, one is not able to see the beam of light but only the...