SPACE OBSERVATION: METHODS AND USE OF TELESCOPE

Image: NASA

Madhu Lamichhane
B.E. Mechanical Engineering

Space is huge. When the only factor of something is ‘time’, it must really be vast. But, what does that mean? That’s where imagination crosses scientific methods of study.

History and Vision

There’s a famous portrait by Da Vinci where he paints a cannonball trajectory, which follows a parabolic arc. This was before Newton discovered the laws of motion. Here, Da Vinci correctly projects the idea of gravity without being backed up by science. This is an example where we can see the how the discoveries might have begun. Enthusiasts, in ancient times, used to study the patterns of the physical world – the path of the moon, its change in shape, the varying position of the stars and the patterns of the constellations, etc. There is another example from ancient Greece where the people had studied all about the weather by studying the seasonal patterns, which they later used to
predict the time of rain and the time of cold. These anecdotes and the stories of The Stonehenge, The Pyramid of Gaza, and The Pyramid of Chichen Itza (they served as astronomical observatories) suggest that the study of the world’s creation and functionality had been the subject of interest from ancient times; people got advanced in theories and tools slowly, which lead us to more profound knowledge of the world and the space.

Metre Telescope

 

Invention of first telescope

Scientific study and research is heavily based on tools and methods. Scientists collect information that serve as data and premise for conclusions using different tools, the first of which was Telescope. First demonstrated by Galileo in 1609, Telescope brought a revolution to astronomy and research. Galileo himself debunked the idea of heliocentric universe which was deeply rooted in the society. Galileo also found out, from the use of his telescope, that the Moon was a world with mountains, that Jupiter had its own moon, and that the Milky Way was a band of countless stars.  Tycho Brahe was another astronomer that made significant contribution to the astronomy, making life long observations from his own observatory using various telescopes.

Galileoscope

 

Modern Age

Larger telescopes collect more light, since they are governed by their diameter. Scientists began to build different telescopes in the pursuit of knowing more. While the Galileoscope was an inch wide, modern telescopes are up to 50 metre wide. These telescopes not only capture the visible spectrum, but also the wide range of waves – from tiny gamma ray to large gravity waves.

The ground based telescopes can be either reflecting or refracting telescope. They collect a vast amount of light from the space that is further studied in the labs. The problem of size can be overcome by using parallel telescopes placed certain distance apart. Examples to such telescope are Keck I and Keck II that are located in Mount Kea in Hawaii. They are two 10 metre wide telescopes with the focal length of 17.5 metre.
VERITAS (Very Energetic Radiation Imaging Telescope Array System) is another important ground based telescope that has four 12m wide mirrors. This telescope detects gamma rays in G ev – T ev energy range. Since the clear image of distant astronomical object cannot be made, scientists study the gamma rays emitted by those objects.

Resolving power throughout time [Credit: Hubblesite.org]

Ground based telescopes serve a great purpose, but the presence of atmosphere limits different waves to reach these telescopes and the artificial lights make the images from those telescopes blurry. That’s why there is ultra-high budgeted Space Telescope. The first space telescope was Ultraviolet Solar Telescope sent by Russian cosmologists. After that a large number of space telescopes have been sent.

Kec I and Keck II in Hawaii [Credit: Arizona State University]

 

Hubble telescope, and it’s construction

Hubble Space Telescope (HST) is the largest space optical telescope which was launched into low Earth orbit in 1990 and still remains in operation. From the joint fund of NASA and ESA HST has been providing continuous data from deep universe. HST lies 250 miles up and has an orbiting period of 90 minutes. It has 2.6m wide mirror, and has four main instruments that observe in near ultraviolet, visible and near infrared spectra. Most of the lights captured by HST are infrared light, radio waves and gamma waves. The formation of true picture of any object from the all mashed up light source is a difficult task. For this, scientists use false imagery. The noises are filtered first and colours are later assigned to make an image complete. And, not only are these images eye candy, they also reveal a lot about what lies beyond the solar system. Along with other Great Observatories like The Compton Gamma Ray Observatory (CGRO), The Chandra X-Ray Observatory (CXO), and The Spitzer Space Telescope (SST), many similar star-planet system have been found till now using HST. It is also helpful in tracing oxygen in those planets.

What’s next ?

Astronomers and space scientists are studying further and the quest has becomes more exhaustive. Many space programmes have already been launched. Cassini-Huygens is another successful mission that sent a probe to study Saturn. Voyager1 is another important probe that has been sent to the space, which has travelled 18.8 billion kilometres from the Earth.

Space image by HST [Credits: NASA]

The main idea behind all these multi-billion dollar projects is that we want to know more. We can’t be alone in the universe! After all, one hundredth of the universe is only in our reach of exploration. We now know about Jovian planets and several Exo-planets, but there are still things that might be useful to us. If we keep digging further into the space, we will have more information about ourselves and the origin of all these things.

Source: coursera.org, nasa.gov

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