Radio serial on astronomy
Episode 2: What is astronomy?
[Note for script writer: This brief has been prepared keeping the average non-specialist viewer in
mind. The attempt has been to develop the subject in a logical sequence that could bring out the
excitement of the process of making new discoveries and relating them to the gradual understanding
of the nature of the Universe. It is not designed to be a popular account of the development of
astronomy as a scientific discipline and its impact on our understanding of the cosmos. Since the
treatment is not rigorous, many details are not included. The script has to be developed along the
outline suggested using simple colloquial language as far as possible. The dialogues and
conversations need to be lively without any suggestion of pedagogy.]
Points to be covered:
- Introduction to astronomy
- Basics of sky watching
- The objectives of astronomy
Outline of content:
Early ideas about the Universe were primarily based on everyday observations and common sense.
To us Earth-bound observers, the Universe is all that we see around us – our Earth, the Sun, Moon,
the planets and the stars. We can hardly visualise things beyond what our eyes can see or our senses
can feel. For example, although it is spinning around its axis and at the same time also going around
the Sun at a break-neck speed, we cannot feel the Earth move. So it is common sense to think that the
Earth is standing still, as our ancestors believed. Similarly, early humans could only see the Sun, the
Moon, five planets and a few thousand stars with the naked eye. So this was their Universe. They
could not imagine that there could be three more planets beyond Saturn or billions of galaxies outside
our own galaxy that make up the real Universe. They did not have the slightest idea about the
vastness of the Universe.
One of the most surprising observations for early humans was the changing appearance of the Moon
in the sky. Unlike the Sun, neither did it rise and set at any fixed times during the day nor did its shape
remain the same. It waxed and waned over a period of about a month, disappearing totally in
between. Sometimes, the Full Moon appeared to darken and then regain its brightness again after
some time. But more frightening was the disappearance of the Sun behind a dark shadow, which
occurred only on some New Moon days. When it happened, the day suddenly turned into night, birds
returned to nest, animals behaved strangely and everything appeared eerie. Of course, the Sun always
came out in its original glory in the end. But it was always a terrifying experience.
The position of the Sun in the sky also does not remain the same throughout the year. The Sun
appears high up in the sky from the northern hemisphere during northern summer, while it appears
low in the southern sky during winter. Similarly, the days are longer during summer and shorter
during winter. What made the Sun change position in the sky and what made the days longer or
shorter?
Answers to all these puzzles are provided by astronomy – the study of the movement of Sun, Moon,
stars and planets in the sky. Astronomy is the study of the universe beyond the Earth’s atmosphere.
Using principles of physics, astronomy explains the evolution of the universe and through sound
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Radio serial on astronomy
mathematical simulations forecasts its development. Although astronomy has been around for
thousands of years and is perhaps the oldest science, it is only in the last century and particularly the
last few decades that we have developed the technology to study the universe in greater detail.
Anyone can enjoy doing astronomy. One only needs to have keen eyesight, a good sense of direction,
and a lot of patience. A pair of binoculars or a small telescope can add a lot to the joy of sky
watching. Although a few thousand stars are visible on a clear, Moonless night, one needs to know
only a hundred or so that make up the constellations to be able to find one’s way across the night sky.
However, before venturing to explore the night sky one must know the north, south, east and west
directions, because if one does not stand facing in the right direction one may not be able to identify a
particular constellation, and correctly indentifying constellations is the first step in astronomy.
Of course, modern astronomy is much more than simple sky watching. Today astronomers use
sophisticated telescopes and instruments to study not only the stars and planets but also a host of other
objects like quasars, pulsars, supernovas, and strange objects that emit radio waves, infrared rays, Xrays, and gamma rays by violent processes. In the mid-20th century, it was discovered that the
universe was expanding. This, along with other evidence, led to the theory of the Big Bang according
to which the entire universe began as a point particle of extreme density. Later observations of the
cosmic microwave background confirmed this, and the Big Bang continues as the primary theory of
cosmological origins to this day. Every day new data on everything from galaxy formation to black
holes to the Big Bang itself are being gathered using a staggering array of multi-wavelength
telescopes on the ground and in space. Orbital observatories such as the Hubble Space Telescope have
produced the best images, including extremely high-resolution photographs of other galaxies. In other
words, astronomy is helping us to understand our Universe better.
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