Introduction to Astronomy

What Is Astronomy?

Astronomy is one of humanity’s oldest sciences. Humans have long gazed toward the heavens, searching to put meaning and order to the universe around them.

Although the movement of constellations — patterns imprinted on the night sky — were the easiest to track, other celestial events such as eclipses and the motion of planets were also charted and predicted.

Definition:

Astronomy is the study of the sun, moon, stars, planets, comets, gas, galaxies, gas, dust and other non-Earthly bodies and phenomena. 

NASA defines astronomy as simple “the study of stars, planets and space.”

Astronomy is a natural science that studies celestial objects and phenomena. It uses mathematics, physics and chemistry in order to explain their origin and evolution.

Astronomy Vs Astrology

It is very important to make this distinction at the very beginning.

Astrology is a field that claims to provide divine information about human affairs and terrestrial events by studying the movements and relative positions of celestial objects.

Although astronomy and astrology were historically associated, astrology is not a science and is no longer recognized as having anything to do with astronomy. 

Astronomy and Astrophysics:

Astronomy has focused on observations of heavenly bodies. It is a close cousin to astrophysics. Succinctly put, astrophysics involves the study of the physics of astronomy and concentrates on the behavior, properties and motion of objects out there.

However, modern astronomy includes many elements of the motions and characteristics of these bodies, and the two terms are often used interchangeably today.

Fields of Astronomy

Modern astronomers tend to fall into two fields:

Observational astronomers focus on direct study of stars, planets, galaxies, and so forth.

Theoretical astronomers model and analyze how systems may have evolved.

Unlike most other fields of science, astronomers are unable to observe a system entirely from birth to death; the lifetime of worlds, stars, and galaxies span millions to billions of years.

Instead, astronomers must rely on snapshots of bodies in various stages of evolution to determine how they formed, evolved and died.

Thus, theoretical and observational astronomy tend to blend together, as theoretical scientists use the information actually collected to create simulations, while the observations serve to confirm the models — or to indicate the need for tweaking them.

Subfields of Astronomy

Astronomy is broken down into a number of subfields, allowing scientists to specialize in particular objects and phenomena.

Planetary Astronomy

Planetary astronomers (also called planetary scientists) focus on the growth, evolution, and death of planets. While most study the worlds inside the solar system, some use the growing body of evidence about planets around other stars to hypothesize what they might be like.

Stellar Astronomy

Stellar astronomers turn their eyes to the stars, including the black holes, nebulae, white dwarfs and supernova that survive stellar deaths. The University of California, LA, says, “The focus of stellar astronomy is on the physical and chemical processes that occur in the universe.”

Solar Astronomy

Solar astronomers spend their time analyzing a single star — our sun. According to NASA, “The quantity and quality of light from the sun varies on time scales from milli-seconds to billions of years.” Understanding those changes can help scientists recognize how Earth is affected. The sun also helps us to understand how other stars work, as it is the only star close enough to reveal details about its surface.

Galactic Astronomy

Galactic astronomers study our galaxy, the Milky Way, while extragalactic astronomers peer outside of it to determine how these collections of stars form, change, and die.

Cosmology

Cosmologists focus on the universe in its entirety, from its violent birth in the Big Bang to its present evolution, all the way to its eventual death. Astronomy is often (not always) about very concrete, observable things, whereas cosmology typically involves large-scale properties of the universe and esoteric, invisible and sometimes purely theoretical things like string theory, dark matter and dark energy, and the notion of multiple universes.

Observational Astronomers

Astronomical observers rely on different wavelengths of the electromagnetic spectrum (from radio waves to visible light and on up to X-rays and gamma-rays) to study the wide span of objects in the universe.

The first telescopes focused on simple optical studies of what could be seen with the naked eye, and many telescopes continue that today.

But as light waves become more or less energetic, they move faster or slower. Different telescopes are necessary to study the various wavelengths.

More energetic radiation, with shorter wavelengths, appears in the form of ultraviolet, X-ray, and gamma-ray wavelengths, while less energetic objects emit longer-wavelength infrared and radio waves.

Astrometry and celestial mechanics

This is the most ancient branch of astronomy and is the measure of motions of the sun, Moon and Planets. The precise calculations of these motions allows astronomers in other fields to model the birth and evolution of planets and stars, and to predict events such as eclipses meteor showers, and the appearance of comets.

Historically, accurate knowledge of the positions of the Sun, Moon, planets and stars has been essential in celestial navigation (the use of celestial objects to guide navigation) and in the making of calendars.

Careful measurement of the positions of the planets has led to a solid understanding of gravitational perturbations, and an ability to determine past and future positions of the planets with great accuracy, a field known as celestial mechanics.

More recently the tracking of near-Earth objects will allow for predictions of close encounters or potential collisions of the Earth with those objects.

Astrochemistry 

Astrochemistry is the study of the abundance and reactions of molecules in the Universe, and their interaction with radiation. This field applicable to both the Solar System and the interstellar medium.

Astrobiology 

Astrobiology is an interdisciplinary scientific field concerned with the origins, evolution, distribution, and future of life in the Universe. Astrobiology considers the question of whether  extra-terrestrial life exists, and how humans can detect it if it does. The term exobiology is similar.

Amateur Astronomy

Amateur Astronomy is a fascinating hobby. Instruments used in ground-based astronomy range from the unaided eye, to common video cameras, to large computer-controlled telescopes using adaptive optics. The hard part is finding dark skies, where you have very little light pollution, that are conveniently located.

Astronomy is one of the few fields where amateurs make significant discoveries and contributions. Some of the notable contributions are:

• Grote Reber an American born amateur astronomer who pioneered radio astronomy. He built his first Radio Telescope in 1937 and made a groundbreaking discovery in the field, by discovering Cygnus A and Cassiopeia A for the first time.

• Discovery of Hale-Bopp Comet by Alan Hale and Thomas Bopp. It was most spectacular in the Northern Hemisphere and was visible to the unaided eye for about 18 long months twice as long as the Great Comet of 1811.

• Scars On Jupiter were first observed and photographed by Anthony Wesley in 2009 and 2010. These Scars were later confirmed by NASA and were roughly the size of the Earth.

• In 2012 Quadruple Star System discovered by an international team of amateur astronomers along with a planet which revolves around four suns in pair of two– the first ever reported case of such a phenomenon. The planet, is located about 5,000 light years from Earth, and has been named PH1 in honour of Planet Hunters.

Now that we have an overview about what is astronomy and its various fields, in the next edition let’s look at the Life Cycle of a Star and learn more about its various stages. From a Nebula to a Proto-Star to a Red Gaint finally how it ends up as a black whole.

Until then stay curious and keep watching the sky.