What are the challenges faced by extremely large telescopes?

Weight, cost, and mirror design limitations.

How did telescopes evolve from refractive lenses to mirrors?

Due to issues like chromatic aberration and weight.

A telescope concept using Earth as a lens.

Through segmented mirror designs.

It enables stable lensing above cloud levels.

Large telescopes with diameters of 30 to 40 meters are being built, but the Terra scope proposes a telescope the size of the Earth, utilizing a physics trick for significant amplification.
The Terra scope project, developed by a Columbia faculty member, involves using Earth as a refractive lens by having light from distant stars skim its surface and converge just inside the moon's orbit, offering a cost-effective alternative with potential applications on other planets.

What are the challenges faced by extremely large telescopes?
Weight, cost, and mirror design limitations.
How did telescopes evolve from refractive lenses to mirrors?
Due to issues like chromatic aberration and weight.
What is the Terra scope project?
A telescope concept using Earth as a lens.
How do reflective telescopes address limitations of large mirrors?
Through segmented mirror designs.
What is the significance of the Terra scope's orbit region?
It enables stable lensing above cloud levels.

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Astronomers are constructing extremely large telescopes with diameters of 30 to 40 meters.
The concept of the Terra scope proposes a telescope the size of the Earth using a physics trick.
In 1608, Hans Lippershey applied for a patent for a telescope with a magnification of up to three times.
Galileo constructed an improved telescope with a magnification factor of 20 using a curved glass lens.
Telescopes transitioned from refractive lenses to mirrors due to issues like chromatic aberration and weight.
Reflective telescopes faced limitations with large mirrors sagging under their weight, leading to segmented mirror designs.
The cost of extremely large telescopes like the TMT or ELT exceeds a billion dollars each.
Larger telescopes like the Colossus or overwhelmingly large telescope aim to detect fainter objects and analyze planets.
Using natural lenses like the Sun or Earth for telescopes has been proposed but faced challenges like distance and practicality.
The Earth could potentially be used as a refractive lens for a telescope, offering colossal lensing capabilities.

18:18

The speaker, a faculty member at Columbia, revisited a problem after 13 years and developed the Terra scope project.
The Terra scope involves light from a distant star skimming Earth's surface and converging at a focal point just inside the moon's orbit.
Surface-skimming rays face obstacles like clouds, mountains, and atmospheric absorption, prompting consideration of higher-altitude rays.
Higher-altitude rays, focused on the Moon's surface, encounter scattering and extinction effects, impacting amplification levels.
To mitigate cloud interference, the speaker proposes using rays above cloud levels, suggesting a stable orbit region around Earth for lensing.
By placing detectors in this orbit region, the Terra scope could achieve significant amplification, enabling advanced astronomical observations.
The Terra scope concept offers a cost-effective alternative to large telescopes, with potential applications on other planets, despite challenges like atmospheric turbulence and alignment issues.