- COMETS: These are actually just an icy bodies ranging from a few hundred meters to tens of kilometres across. They are made up of ice, dust and small rocky particles. The word has been derived from the Latin word cometes, a derivation of a Greek word, meaning ‘long haired star’. The comets usually orbit the sun, and take a long elliptical path across our solar system. When the comet comes close to feel the heat of the Sun, the ice starts to evaporate, thus causing the tail that we see with our naked eyes, for e.g, HALLEY’s comet. I’m sure a lot of us have wished upon comets, thinking them to be shooting stars
- RED GIANT: All stars, including our Sun, have a certain life span. For e.g., our Sun has been around for nearly 5 billion years and is quite stable at this moment, but 7-8 billion years down the line or more, the Sun will exhaust its energy supplies at the core. Our star generates its energy by nuclear fusion of hydrogen nuclei into helium. After a point of time, the hydrogen reserves in the core will be exhausted and thermonuclear fusion of hydrogen in a shell surrounding the core will take place. After evolving through the hydrogen burning phase, the Sun will puff up into a huge giant Red Star as the hydrogen fuel becomes scarce, expanding to cause the Sun to have radii tens to hundreds of times larger than that of the present size. The larger size will affect the planets and celestial bodies around it, like our Earth which will get swallowed by the Sun. The temperature of the Red Giant will be considerably less than our present Sun, thereby giving it the reddish hue.
- WHITE DWARF: A dying star can either explode in a supernova (like a massive explosion), or it can become a white dwarf after the RED GIANT stage passes. Here the star goes through the thermonuclear fusion of hydrogen, then the second phase of the helium fusion and after shedding its outer layers, the carbon-oxygen core will be exposed. Although there are no more fusions taking place, the remnant is still very hot, therefore the white colour.
- BLACK HOLE: Black holes form when the center of a very massive star collapses in upon itself. This catastrophic collapse results in a huge amount of mass being concentrated in an incredibly small area. The gravitational pull of this region is so great that nothing can escape – not even light!!! Matter falling into a black hole can form an accretion disk, which heated by friction creates a lot of energy. All matter in close proximity gets pulled into the hole, and till date what lies beyond is a mystery. There is an ‘Event Horizon’ a point which is crossed by any object, no information can be transmitted. We observe a sort of gravitational space time lapse – To a distant observer, clocks near a black hole appear to tick more slowly than those further away from the black hole. Due to this effect, known as gravitational time dilation, an object falling into a black hole appears to slow down as it approaches the event horizon, taking an infinite time to reach it.
A black hole will appear utterly dark in space as no light can escape its boundaries.
It is believed that all galaxies in our Universe contain at least 1 super massive Black hole at it’s centre.
- PULSAR: One of the most interesting things in our known Universe, Pulsars exist in the centre of Super Massive Black Holes. It is basically a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. (A neutron star would be so dense, that on Earth, one teaspoonful would weight a billion tons!!!) We only partially understand how this works, and the energy output generated by a pulsar in enormous! To set things in perspective in terms of relative sizes, if a 1 kilometer wide volume of space were radiating strongly at various wavelengths, most of the power being supplied would be by a single hydrogen atom at the center of that volume! WOW!!! Btw, they ‘pulsate’ as in, they rotate, so people on Earth would see a pulsar as a pulsating light.
That’s all for now folks – hope you liked it! I love space, and anything to do with it, and hope this was easy to read and understand!