Astronomy, derived from the Greek words for star law, is the scientific study of all objects beyond our world. It is also the process by which we seek to understand the physical laws and origins of our universe.
Founder of Astronomy
Nicolaus Copernicus (1473 – 1543): He was a Polish physician and is now regarded as the father of the current heliocentric model of the solar system.
Tycho Brahe (1546 – 1601): A Danish nobleman, Tycho designed and built instruments & used these instruments to chart the positions of planets and other celestial objects with such great precision, that it debunked many of the commonly held notions of planetary and stellar motion.
Johannes Kepler (1571 – 1630): A student of Tycho’s, Kepler. He discovered three laws of planetary motion:
- Planets move in elliptical orbits with the Sun at one focus of the ellipse.
- The orbital speed of a planet varies so that a line joining the Sun and the planet will sweep over equal areas in equal time intervals.
- The amount of time a planet takes to orbit the Sun is related to its orbit’s size, such that he period, P, squared is proportional to the semi-major axis, a, cubed.
Galileo Galilei (1564 – 1642): He was the first to use the telescope to make detailed studies of heavenly bodies. He was the first to conclude that the Moon was likely similar in composition to the Earth, and that the Sun’s surface changed (i.e., the motion of sunspots on the Sun’s surface). He was also the first to see four of Jupiter’s moons, and the phases of Venus. Ultimately it was his observations of the Milky Way, specifically the detection of countless stars, that shook the scientific community.
Isaac Newton (1642 – 1727): Newton not only deduced the law of gravity, but realized the need for a new type of mathematics (calculus) to describe it. His discoveries and theories dictated the direction of science for more than 200 years, and truly ushered in the era of modern astronomy.
Albert Einstein (1879 – 1955): Einstein is famous for his development of general relativity, a correction to Newton’s law of gravity. But, his relation of energy to mass (E=mc2) is also important to astronomy, as it is the basis for which we understand how the Sun, and other stars, fuse hydrogen into Helium for energy.
Edwin Hubble (1889 – 1953): During his career, Hubble answered two of the biggest questions plaguing astronomers at the time. He determined that so-called spiral nebulae were, in fact, other galaxies, proving that the Universe extends well beyond our own galaxy. Hubble then followed up that discovery by showing that these other galaxies were receding at speeds proportional to their distances away form us.
Stephen Hawking (1942 – ): Very few scientists alive today have contributed more to the advancement of their fields than Stephen Hawking. His work has significantly increased our knowledge of black holes and other exotic celestial objects. Also, and perhaps more importantly, Hawking has made significant strides in advancing our understanding of the Universe and its creation.
Types of Astronomy
There are really two main branches of astronomy: optical astronomy (the study of celestial objects in the visible band) and non-optical astronomy (the use of instruments to study objects in the radio through gamma-ray wavelengths).
Optical Astronomy: Optical astronomy means use of telescope or use of Optics for astronomy studies & research. Like Hubble Space Telescope (HST), or images of the planets taken by various space probes.
Non-optical Astronomy: There are other types of observatories allowed us to create a picture of our universe that spans the entire electromagnetic spectrum, from low energy radio signals, to ultra high energy gamma-rays. They give us information about the evolution and physics of some of the Universe’s most dynamic treasures, such as neutron stars and black holes.
There are so many types of objects that astronomers study, that it is convenient to break astronomy up into sub fields of study.
Planetary Astronomy: Researchers studies on planets, both within and outside our solar system, as well as asteroids and comets.
Solar Astronomy: Interested in learning how the Sun changes and trying to understand how these changes affect the Earth.
Stellar Astronomy: Simply, the study of stars, including their creation, evolution and death.
Galactic Astronomy: study the motion and evolution of the Milky Way in order to learn how galaxies are formed.
Extragalactic Astronomy: Astronomers study other galaxies in the Universe to learn how galaxies are grouped and interact on a large scale.
Cosmology: Cosmologists study the structure of the Universe in order to understand its creation.