Humans have been connected to astronomy since the origin of human life on Earth. Back in ancient times, in the entire landscape, the sky was always the largest as well as the fastest moving element (apart from animals and birds, although they were pretty small compared to the sky). Over history, the sky, and everything that was observed about it was used for a lot of purposes ranging from keeping track of time to orienting cities to even predicting the future. To try and document the entire history of astronomy would be attempting an astronomical feat in itself and would probably need a lot more literature than a magazine. But what we are going to do today is trace the origin of modern astronomy and figure out how we got from worshipping the sky to observing the universe like never before.
But first, a history lesson
Any recap on astronomy would be incomplete without a briefing on the views held during ancient times. Astronomy has affected human civilisation before there were civilisations. The true earliest known records of astronomy come in the form of sticks and stones from Africa and Europe as far back as 35000 BCE (used to track the moon’s phases). And somewhere along the line, we landed up with a geocentric model of not only our own solar system but an entire universe!
Ancient Sanskrit treatise Surya Siddhanta asserted the spherical shape of the earth, the diameter of 8000 miles (modern: 7,928 miles), the moon’s diameter as 2,400 miles (actual ~2,160) and the distance between moon and earth to be 258,000 miles (actual ~238,000) as early as 4th century CE.
If it’s not clear yet, we consistently believed (even after more believable alternatives were proposed) that earth is the centre of the universe. Talk about self-importance, eh? Well, this could be chalked up to the lack of proper measuring instruments or techniques until later in time. This was a model that was held on to since the beginning of recorded history up until as late as the late 16th century.
It wasn’t until the alternative heliocentric model was proposed by Copernicus that the earlier geocentric theory was shunned and replaced. However, even his theory was far from perfect because it still contained the assumption that planetary orbits are circular.
Galileo and the telescope
Around the beginning of the 17th century, a new type of observational device was being built and popularised. The refracting telescope was initially invented by Dutch eyeglass maker Hans Lippershey and was going to be one of the most significant inventions in the history of astronomy. With the quick proliferation of his design and other inspired alternatives, astronomy saw a revolution like never before.
Within the next two years, two of the most significant people to modern astronomy – Johannes Kepler and Galileo Galilei published their seminal works. While Kepler’s laws of planetary motion shun the circular orbits of planets for elliptical ones, Galileo records observations with his improvised telescope that haven’t been seen before – spots on the sun, craters on the moon and moons of Jupiter. This could very well have been the strongest evidence of the heliocentric model being correct yet. The next century was nothing short of glorious with more powerful telescopes leading to increasingly accurate observations and several corrections to earlier flawed beliefs.
Sir Isaac Newton, with his observations based on his self-designed reflecting telescope, published his Philosophiae Naturalis Principia Mathematica in 1687 establishing, among other things, the laws of gravitation. These very laws have helped astronomers greatly in understanding the forces between celestial bodies. The next century saw amateur astronomers take astronomy to new levels by discovering new planets (Uranus), comets (Halley) and even laying the foundations of spectroscopy.
Spectroscopy and spectrometer
The discovery of the spectrum beyond visible light was almost an accident. William Herschel had split sunlight through a prism and then proceeded to measure the energy given out by different colours with a thermometer. He observed a sudden increase in energy beyond the red end of the spectrum, discovering invisible infrared and laying the foundations of spectroscopy. The first accurate spectrometer was built by Joseph von Fraunhofer in 1814, which eventually led to the study of what stars are made of based on the spectral radiation they emit.
A new bright line in the sun’s spectrum was observed in 1868 and was concluded to be an element unknown to Earth. British astronomer Norman Lockyer calls it helium, which is Greek for the Sun. About 30 years later, Helium was discovered on Earth.
Another amateur astronomy discovery of note was the discovery of the stellar parallax effect by Friedrich Bessel. He used it to measure the distance to 61 Cygni from Earth quite accurately. This method is in practice even today in the estimation of interstellar distances.
While people, mostly amateur astronomers and scientists, realised the potential of photography as a tool for astronomical observation, there were technical challenges involved. These included ensuring the rigidity of telescopes so they wouldn’t dip out of focus during the exposure, using the correct clock drives to rotate the telescope mount at a constant rate, and mostly develop ways to keep a telescope accurately aimed at a fixed point over a long period of time. Another influential factor was the limitations of early photographic processes. The daguerreotype process was far too slow to record anything but the brightest objects, and the wet plate collodion process limited exposures to the time the plate could stay wet.
The first real scientific astrophotograph was obtained by French physicists Jean Foucault and Armand Fizeau, as the picture of the Sun’s surface through a telescope. Soon enough, people realised the potential of this technique and better methods along with technological advancements led to better and clearer pictures. Consequently, these pictures capture a range of phenomena and celestial bodies like a solar eclipse, the moon and more to provide astronomers greater clarity in their study of the cosmos. Post the 1872 photograph of Vega by Henry Draper that showed absorption lines, William Huggins used absorption lines to measure the redshift in stars, giving, for the first time, an indication to how fast stars are moving.
Today, amateur astrophotography is possible even on common film and digital cameras with basic equipment. For simple star trails, no equipment may be necessary other than common tripods. There is a wide range of commercial equipment geared toward basic and advanced astrophotography, like single-lens reflex cameras, 35mm film, digital single-lens reflex cameras, simple amateur-level and professional-level commercially manufactured astronomical CCD cameras, video cameras, and even off-the-shelf webcams adapted for long-exposure imaging. Amateur astronomers and amateur telescope makers also use homemade equipment and modified devices. A deeper look into amateur astrophotography calls for an entirely different article by itself.
Mega telescopes and Probes, Ahoy!
Over the long course of modern astronomy that has been discussed, devices have been built and improved consistently by amateur astronomers and scientists alike, especially when they weren’t satisfied with the existing state-of-the-art. Listing each innovation that outdid the previous one’s accomplishments would be a wasted effort. Rather, here’s a couple of these that are, to this date, considered milestones by themselves:
- Very Large Array: An array of 27 radio antennas, each 25 metre across, in New Mexico that is still used to study everything from black holes to planetary nebulae.
- Hubble Space Telescope: Since its launch in April 1990, the Hubble telescope hasn’t looked back. It has been used to study everything from the expansion rate of the universe to discover dark energy.
Another area where astronomy has been greatly helped by technology is with probes. In the long list of accomplishments that space probes have achieved, there are a few that are particularly significant.
- The Rosetta orbiter and the Philae lander that managed to land on comet 67P.
- The Voyager 1 and 2 have travelled furthest and completed the grand tour of the gas giants in our solar system, providing us more detailed images of these planets than ever before. The Voyager 1 is currently the farthest man-made object from earth.
With advancements in astronomical technology having taken us to outer space, the next frontier is to actually go beyond the bounds of our solar system and observe other stars and their systems up close. Astronomy has grown from being an observatory science to something that actually affects the future of humanity, as our quest to find an alternative planet to colonise draws nearer with each innovation in the space race. And if you want to be a part of this exploration, don’t worry, we’ll cover that soon as well!