Astronomy for Dummies

Article by : Tarini AA - always has her head in the clouds.

Throughout history, humans have looked up at the sky to navigate the vast oceans, to sow their seeds, to count their days and to answer questions we can’t find answers to. Early civilizations interpreted celestial movements to be Gods and Monsters. The skies have a way of hiding mind-blowing mysteries in plain sight. Maybe that’s why even though astronomy was the first science to reach a higher level of sophistication, space still remains our least explored frontier.

So strap in for a quick charge into the fascinating world of Astronomy. But looking for something deeper? Check the official blog of the Horizon Club for in-depth articles on astronomy and physics.

Brief History of Astronomy:

 The human fascination for space is as old as space itself. The oldest astronomical tool discovered is a 32,500-year-old star chart carved out of a mammoth tusk. Astronomy was largely studied through observations and recognizing repeating patterns. The 1st-2nd millennia Babylonians used mathematics and the periodic nature of celestial phenomena to make accurate predictions. The Greeks were the first to apply geometry to study the night sky. They documented that the Earth is a sphere, much before Magellan’s historic voyage and even calculated its circumference to great accuracy.

During the Renaissance, astronomy went through something called the Copernican Revolution. Church proposed theories were questioned and challenged with science. The discovery of telescopes in the 17th century strengthened our observations and investigations. Study of planetary motion by Tycho Brahe and Johannes Kepler laid the foundation for Newton’s theory of gravitation. Since then, mankind has done a great job of mapping stars and their systems, even achieving the Herculean task of interplanetary travel.

Modern Astronomy:

 From observing patterns on the sky, to reusable spacecraft, astronomy has come a long way. Modern astronomy branches out into four major fields.

Astrophysics:

Much like Geophysics, which applies the law of physics on Earth, Astrophysics tries to understand the physical properties and processes of celestial bodies and their surrounding space.

Cosmology in particular deals with origin, evolution and expansion of the Universe.

Spectroscopy deals with how light reflects, absorbs and transfers between matter.

Photometry uses electromagnetic radiations to examine the nature of luminous objects in space.

Heliophysics studies the physics of the Sun and its dynamic radiation.

Heliosiesmology and Asteroseismology focuses on studying the internal structure and dynamics of the Sun and the stars, the latter is done through observing their oscillations while the former is achieved through observing waves on the surface.

High energy astrophysics deals with high energy phenomena such as active supernovae, gamma ray bursts, quasars, etc

Astrometry:

While astrophysics deals with the physics that drive the motion of the stars, astrometry focuses more on the precise measurement of positions and movements of stars. This branch of study provides insight into the kinematics and physical origin of the Universe.

Planetology studies the origin, composition and dynamics of the planets in our solar system while exoplanetology deals with the planets revolving around other star systems.

 Astrogeology:

Also called as planetary geology or exogeology, astrogeology deals with analyzing rock samples collected from extra terrestrial bodies such as planets and their moons, asteroids, comets and meteorites to study their composition and geology.

Astrobiology:

Astrobiology or Xenobiology involves the search for life outside our planet. Astrobiologists investigate planets and their moons for the necessary conditions and environment for the possibility of life or traces of life in the past. Some astrobiologists are also involved in recording and investigating radio signals from other galaxies.

Observational Astronomy:

 Like the name suggests, observational astronomy is concerned with observing and recording  data of the observable universe with telescopes and other astronomical apparatuses. Observational astronomy can be classified with the range of the electromagnetic spectrum that is observed, like Radio astronomy, Infrared astronomy, optical astronomy, high energy (X-Ray, Gamma rays, UV rays) astronomy and occultation (eclipses). In addition to the electromagnetic spectrum, observations can also be made using neutrinos, cosmic rays or gravitational waves.

Observation Tools:

Telescopes:

The most important tool to observe the Universe is the humble telescope. Most modern telescopes use an array of telescopes to offer a high-resolution image through aperture synthesis. Large telescopes are mounted on domes, to stabilize them and to protect them from environmental wear and tear. Before the advent of computer-controlled drive mechanics, telescopes used something called the equatorial mount, where rotational axis is fixed parallel to the Earths rotational axis was used to compensate for the Earth’s rotation.

Micrometer:

Micrometer is an instrument used to measure double stars, consisting of a pair of fine movable lines. Telescope lenses are lined up on the lines in a way that they are perpendicular to the star segregation and then adjusted to match the star positions. The true separation of the stars is then determined based on the magnification of the image

Spectrograph:

The absorption of specific wavelengths of light by certain elements present in the star allows one to determine certain properties of the star. This instrument was used to discover Helium in the Sun’s emission spectrum.

Photoelectric Photometry:

These super sensitive instruments can record an image down to the level of a single photon and are now being widely used to make observations through telescopes. The computer then corrects the atmospheric effects through stacking, where multiple images are stacked on top of each other digitally to reduce noise.

 The more we learn about the stars, the more we learn about ourselves. We are made of the same stuff that makes the stars. To get started with astrophotography, check out our Instagram post. If the stellar world of stars and supernovae excites you, check out the Horizon club's official blog