February 22, 2019



What Size is the Hubble Telescope Mirror?

• The Hubble is almost 13 meters long weighing close to 11 tones; its primary mirror has a diameter of 2.4 meters.

From the dawn of humankind until the beginning of the 17th century, people would observe the sky with only naked eyes!

Everyone then wondered if we could ever resolve the mysteries of stars and planets!

This became possible to a certain extent when at the beginning of the 17th century, in 1608, a Dutch resident, an expert in the making of spectacles, came out with a device called telescope– that heralded a new age in astronomy.

Based on this device, Thomas Harriot in England and Simon Marius in Germany could observe the night sky in those days with some authenticity!


At that time, Galileo Galilee was also in the process of constructing a telescope.

While he heard about the device that was built in the Netherlands, he continued with his experiments to developing an instrument that could help him see the night sky with some magnification!

He could arrange two lenses, one convex and another concave, in a tube that magnified the distant objects at least three times!

After several experiments, he further improved the device that magnified the objects at least 30 times! This was a major success for him in those primitive years when only a handful of the people were interested in finding the truth about the planetary movements.

After this creation, he was awarded a lectureship at the University of Padua, in Italy. He profoundly made use of his telescope to describe the surface of the moon.

He also studied the different phases of the Moon in detail and described them. Using the telescope, he discovered the rings of Saturn and moons of Jupiter!

That was indeed a big achievement in those days!

Soon the words spread around Europe quickly and many more people got interested in designing telescopes. Johannes Kepler was one of them.

In 1611, Kepler studied optics in great depth and developed his device using two convex lenses, which would soon know as the Keplerian Telescope.

While he was able to improve magnification of the objects several times, his device turned the images upside down. Because of his work on optics, he came to be known as the ‘Founder of Modern Optics.’

Dioptrice’ was the work that explained the concept of magnification for the first time. He laid the foundation of the basic science of making telescopes.

In 1655, Christian Huygens made a next-generation telescope through which he could observe planets and solar system. His telescope was 12 feet long with which he had made detailed observations of Saturn.

He could see moons of Saturn through this telescope that would come to be known as Titan in 1847!

The telescopes so far made were refractive and had the issue of chromatic aberration or distortion, which is also known as the failure of a lens to focus light at one point.

In a bid to remove the issue of chromatic aberration, Isaac Newton developed the first reflecting telescope in 1668!

This telescope was not only free of chromatic aberration but simpler to make. Wider field of view became an advantage through this telescope. From a portability perspective, the reflector telescope scored over all previous versions of the telescopes.

The color distortion issue with refracting telescopes was greatly reduced in the next six decades or so when Chester Moore Hall used crown and flint glass to built telescopes.

The year 1789 made a big leap when in the UK, a 12-meter long reflector telescope was constructed under the supervision of William Herschel, an astronomer, and scientist.

This was the largest telescope ever made during those days in the entire world!

The telescope came to be known as the Herschellian telescope. Because of its length, the telescope had some issues. Using this telescope, Herschel could discover not only Uranus but some of its moons such as Titania and Oberon!

Then the World came to know about the largest refracting telescope in the year 1897 when it became ready at the Yerkes Observatory in Williams Bay, Wisconsin. The telescope used the lens having a huge size of 102 cm in diameter!

In the 20th century, famous astronomers such as Edwin Hubble, Gerand kuiper, Subramanian Chandrasekhar had been associated with the Yerkes observatory during their astronomy-related research work.

The 20th century has seen some of the remarkable developments in the making of telescopes in which the Radio Telescope is one of them.

Sir Bernard Lovell, the British Astronomer, visualized great potential in radio telescopes that he finally commissioned at Jodrell Bank in the UK in 1957.

The radio telescope played a pivotal role in the research of pulsars, meteors, quasars!

From there on, a big jump came in the form of Hubble Space Telescope, which was launched in 1990 by NASA in cooperation with European Space Agency. It has been deployed into low earth orbit since then to send us the images that we have never received before that!

Counting from the days of Galileo Galilee, it took almost four centuries for science and technology to make such a big leap forward when it became possible to know about the thousands of galaxies that were never known to the humankind.

The key advantage of Hubble is that it bypasses the Earth’s atmosphere completely, which is the major hindrance in the imaging process.

Being deployed in space, Hubble provides very clear images of the stars, galaxies, nebulas that will never be possible from Earth.

It is sensitive to light having wavelengths of 115-2500 nanometers. It is inclined to 28.5 degrees to the equator and completes one round of the Earth in almost 95 minutes.

Between 1993 and 2009 it has been serviced five times to increase its useful life.


Some Interesting Facts about Hubble Space Telescope


The Hubble gets its power from the solar panels fitted to it; its power requirement is only 2.8 KW. Any household would consume more power than this during peak winter or summer!

The Hubble is equipped with nickel-hydrogen batteries for storing power produced by its solar panels. In storage capacity, these batteries are equivalent to 22 average car batteries.

It orbits the Earth at the unbelievable speed of 28,000 km/h to counter Earth’s gravity. How fast it is speeding can be gauged from the fact that any supersonic aircraft will have the speed of 2200 km/h.

The Hubble is equipped with a giant CCD camera capable of capturing the images of very far-off galaxies; it has had over 1.3 million observations since its launch.

It transmits almost 150 gigabits of useful data in a week; based on these data, Scientists/astronomers have been able to publish over 15,000 scientific research papers so far.

From the images rendered by the Hubble, scientists have been able to ascertain the age of this universe at 13.8 billion.

The limitation of the Hubble has been that it is not sensitive to infrared light and therefore, cannot go back in time to the origin of the universe.

While its useful life is almost over, it has not yet finished. It will continue to serve us for some more years until the time when the James Webb Space Telescope is ready for launch in March 2021.

Use a telescope to view saturn, orion.