Celestial objects have excited human curiosity ever since they have been spotted in the night sky. The desire to know more drove humans to study in more detail the objects that we know as planets, stars, moons, galaxies, comets and phenomena. Thus the natural sciense Astronomy has been born.

There were early civilisations such as Egyptians, Babylonians, Maya and other who methodically observed the night sky. The observation methods got more and more sophisticated and evolved to very complex scientific disciplines over the centuries.

We can say that the Astronomy is the oldest among the natural sciences. And still there are questions which have not been answered yet but there are theories around formulared, discussed and explored by curious fellows. Astronomy still has space to grow.

Understanding the Universe, such as the laws that govern celestial bodies in the night sky, what was their¬†development and how will they develop further, what is our role in it, what will be the future of the Sun,¬†moons, planets¬†and the Solar System¬†as a whole, etc. ‚Äď these are all questions which people ask from immemorial, from the first view of the breathtaking scenery of the night sky. The same questions are undoubtedly the greatest motivation for astronomores to¬†understand the Universe.

Astronomy is the first classical science

Venus and Mars forming a triangle with the Moon in the evening sky. Astrophotographer Greg Diesel Walck caught this view of the trio through trees in coastal North Carolina on Feb. 20, 2015. Greg Diesel Walck

Astronomers began to use observation as a means to confirm or disconfirm our theories about the processes leading to the formation of various celestial bodies and the Universe as a whole. This was from the outset a need to develop ingenious devices, at the best possible technical level, which allow astronomers to observe and record their results. The mathematics has become an equally important tool of knowledge which has been the basis for a deeper understanding of the behavior of the observed objects, including planets and their satellites, their origins, movements, and developments. Astronomy was the first to develop and put into practice procedures now commonly used in other branches of science.

Definition and history of astronomy

Astronomy¬†is the study of physics¬†and components of observable Universe.¬†Professional and amateur astronomers¬†study¬†the Sun, moons, stars, planets, comets, gases, galaxies, clusters, dust and other unearthly¬†bodies and phenomena.¬†Astronomy studies¬†the Universe itself¬†through observation and theory and the professional scientists who are engaged in these studies are called¬†astronomers, or astrophysicists.¬†Some simply define¬†astronomy as¬†‚Äúthe study of¬†stars,¬†planets, and space.‚ÄĚ Our ancestors were gazing towards the heaven, searching and trying to put some meaning and order to the universe around them.

Astronomy and astrology were historically associated. But astrology is not a science and it is no longer recognized as something that has to do anything with astronomy. Astronomy should not be confused with the practice of astrology which makes claims based on superstition or supernatural causes which either cannot be falsified or have been consistently disproved.

Astronomy, astrophysics and cosmology

Astronomy focused on observations of celestial bodies, the first stars in the sky and planets later historically. Astronomy, as a science, is a close cousin to astrophysics. Succinctly put, astrophysics involves the study of physics of astronomy and concentrates on behavior, properties and motion of astronomical objects out there. However, modern astronomy includes many elements of motions and characteristics of these bodies and the two terms are often used interchangeably today. Planetary astronomy is mainly dealing with all kinds of planets occurring within our Solar System. Cosmology is focused 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) focused on very concrete, observable things. On the other hand, 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 as well as the notion of multiple universes.

Modern astronomy

Modern astronomers have full control of not only physics and mathematical methods, but computers and modern technology as well. They must constantly learn and adapt to new knowledge. If it wasn‚Äėt so, the flow of exciting discoveries and discovered secrets of the Universe would rapidly slow down. However, new discoveries¬†can not¬†be planned, such an approach does not work in any science. New discoveries often happen as happy coincidence rather than planned research and observation calendar. Every professional or amateur astronomer must be ready to go through various situations and have to be able to recognize newly offered opportunities to reveal something fundamental. Cosmic microwave background is a classic example of such accidental discovery which significantly influenced our view of the universe. This discovery refuted the theory of a static Universe and supported the Big Bang theory.

Observational and theoretical astronomy

In February 2007 NASA's New Horizons spacecraft flew by Jupiter and captured this photo of the gas giant with its volcanic moon, Io. Jupiter's strong gravity gave the spacecraft a 9.000-mile per hour (14,484 km/h) speed boost en route to Pluto, cutting the spacecraft's total travel time by three years. Credit: NASA/JHUAPL/SWRI

Unlike most other fields of science, astronomers are unable to observe a system entirely from birth to death. The life of various worlds, stars, planets, and galaxies span millions to billions of years. As such, 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.¬†Observational astronomers,¬†in the observational field, focus on the direct study of stars, planets, galaxies, and so forth.¬†Theoretical astronomers¬†model and analyze how systems may have evolved.¬†They¬†use the actually collected information to create simulations, while the observations serve to confirm the models¬†or to indicate the need for tweaking them.¬†The two types of astronomers depend on one another ‚Äď observers make observations with telescopes to test astronomical theories or to try and understand unanswered questions. Theorists use these observations to improve their understanding of physical laws and to test their models. As such the division between observers and theorists is blurry and the two groups are far from mutually exclusive.

All types of planets are studied by planetary astronomy

Planetary astronomers focus¬†on the growth, evolution, and death of planets, while solar astronomers spend their time analyzing a single star ‚Äď our Sun. Stellar astronomers turn their sight to the stars, including the black holes, nebulae, white dwarfs, and supernova that survive stellar deaths.¬†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.¬†Astronomical observers rely on different wavelengths of the¬†electromagnetic spectrum¬†(from radio waves to visible light and 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 to do that today.¬†Astrometry, the most ancient branch of astronomy, is the measure of the¬†Sun,¬†moon, and¬†planets. The precise calculations of these motions allow, 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.