Astrophysicist

The year was 1665. Italian astronomer Giovanni Cassini turned his telescope to the planet Jupiter and made an amazing discovery a large “permanent” spot in the southern hemisphere of the giant planet. Cassini and his successors observed the permanent spot regularly until 1712. Only sporadic observations occurred for the next 165 years, but the Great red spot has been systematically observed since 1878.  Despite the been large gap in the record, many astronomers think that the Great Red Spot has existed for more than 340 years, longer than the United States  has been a country. Nevertheless, the Great Red Spot’s definitive existence for the past 130 years makes it the Solar System’s longest-lived storm, Not only is the Great Red Spot long-lived, it is also immense and intense. Approximately three Earths would fit inside Jupiter’s massive storm system. The Great Red Spot towers 8 km (5 miles) over the surrounding cloud tops, nearly the height of Mount Everest. The giant whirlpool is

In 1932, the neutron was discovered. As mentioned above, two years later, Walter Baade and Fritz Zwicky at the California Institute of Technology hypothesized stars consisting essentially of neutrons. The idea was that if one compresses a star to a density of 10^14 g cm^-3-the density of the nuclei of atoms we are familiar with then the repulsive force between the neutrons. practically touching one another. would prevent any further compression, and the star will be stable. It is just like packing a football with ball bearings; when the ball is jam-packed. it will be quite incompressible. This hypothesis led physicists to the conclusion that even stars more massive than 1.4M ☉   could find ultimate peace. not as white dwarfs but as neutron stars. A density of 10^14 g cm^-3 implies that such stars would be incredibly small, with a radius of mere 10 kilometres! So it appeared that all stars will find peace after all, either as white dwarfs or neutron stars, but this turned out to

A major problem arose in 1925 when an extraordinary star was discovered. Although it was as massive as Sun, it was only as big as the Earth! This meant that the average density of the star was about 10^6 g.cm^-3 (the mean density of the Sun is only a little more than that of water). The difficulty posed by such a dense star was the following. What will happen to such a star when nuclear energy generation at its center stops? Since the star will no longer produce heat, there will be no force to oppose gravity. What will be the end state of such a star? Surprisingly, the resolution of this problem came from the newly emerging Quantum Physics. In 1926, R. H. Fowler at Cambridge University argued that the star will collapse and collapse till it reaches a density where a new quantum mechanical force provides support against gravity, and the star will at last find peace. This quantum pressure is due to the electrons and arises due to the combination effect of Heisenberg`s principle of

As already mentioned( https://forastrophysicist.blogspot.com/2019/08/the-revolution-that-was-unfolding-at.html?m=1 ), Fraunhofer`s discovery of dark lines in the spectrum of the Sun enabled the physicists to conclude that the Sun`s outer layers were gaseous. By 1870, the Sun and the stars had been modelled as spheres, held together by their own gravity. The outstanding question at the turn of the nineteenth century was the following: what is the source of energy that makes the star shine? In 1920, Sir Arthur Eddington at Cambridge University in England made the extraordinary suggestion that the source of energy was the transmutation of hydrogen into helium at the center of the stars. He went on to construct a detailed theory of the stars based upon the simple principle that the inward-directed force due to self-Gravity was balanced by the combined pressure of the gas and radiation, both of which are directed outwards. Despite its simplicity, many predictions of this theory were i

A diagram of the structure of the  maximally extended black hole   spacetime. The horizontal direction is space and the vertical direction is time. The equations of General relativity have an interesting mathematical property: they are symmetric in time. That means that you can take any solution to the equations and imagine that time flows backwards rather than forwards, and you will get another valid solution to the equations. If you apply this rule to the solution that describes Black Holes, you get an object known as White Hole. Since a Black Hole is a region of space from which nothing can escape not even light the Time-Reversed version of a Black Hole is a region of space into which nothing can fall. In fact, just as a Black Hole can only suck things in, a White Hole can only spit things out. White holes are a perfectly valid mathematical solution to the equations of General relativity, but that does not mean that they actually exist in nature. In fact they almost ce

Well, first, let me assure you that the Sun has no intention of doing any such thing. Only Stars that weigh considerably more than the Sun end their lives as Black Holes. The Sun is going to stay roughly the way it is for another five billion years or so. Then it will go through a brief phase as a red giant Star. During which time it will expand to engulf the planets Mercury and Venus and make life quite uncomfortable on Earth (oceans boiling, atmosphere escaping, that sort of things). After that, the Sun will end its life by becoming a boring White Dwarf Star. If I were you, I do make plans to move somewhere far away before any of this happens. But I digress. What if the sun did become a Black Hole for some reason? The main effect is that it would get very dark and very cold around here. The earth and the others planets would not get sucked into the Black Hole; they would keep on orbiting in exactly the same paths they follow right now. Why? Because the horizon of this Blac