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20.Telescope (a little bit of history)

  In 1608 Hans Lippershey, an eyeglass maker, submitted the first patent of telescope. But who made the first telescope, it is not clear. Later on, Galileo improved the design and started applying in Astronomy. This telescope had convex objective lens and concave eyepiece lens. In 1611 Kepler developed the design using convex lens in both objective and eyepiece and this design was more useful than the previous one developed by Galileo. Diagram of Galilean and Keplerian Telescope In 1655 Huygen was making powerful and enhanced Keplarian telescopes using compound eyepiece but those telescopes were proved inaccurate. In 1688 Isaac Newton built the first reflector telescope which consisted of a tiny flat diagonal mirror to reflect the incoming light on an eyepiece. Using achromatic lens, in 1733, Chester Moore Hall built a telescope. First Reflector Telescope built by Newton Diagram of Achromatic Lens When light of white color passes through a medium it splits into several colors. For exam
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Starquake!

 


A starquake is an astrophysical phenomenon that occurs when the crust of a neutron star undergoes a sudden adjustment, analogous to an earthquake on Earth.

Reasons for Starquakes:

Starquakes are thought to result from two different mechanisms.

1.   One is the huge stresses exerted on the surface of the neutron star produced by twists in the ultra strong interior magnetic fields.

2.   A second cause is a result of spindown. As the neutron star loses angular velocity, due to frame dragging and by the bleeding off of energy due to it being a rotating magnetic dipole, the crust develops an enormous amount of stress. Once that exceeds a certain level, it adjusts itself to a shape closer to non-rotating equilibrium: a perfect sphere. The actual change is believed to be on the order of micrometers or less and occurs in less than a millionth of second.

Findings of a Starquake:    

The largest recorded starquake was detected on December 27, 2004 from the ultra-compact stellar corpse SGR 1806-20. It has been calculated that the energy released would be equivalent to a magnitude of 32 quakes. The quake, which occurred 50,000 light years from Earth, released gamma rays equivalent to 1037 kw. Had it occurred within a distance of 10 light years from Earth, the quake could have triggered a mass extinction.

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