Muggle and wizarding studies of astronomy overlap greatly, so wizard astronomers tend to use many of the same tools as their Muggle counterparts. In this chapter, you will learn about the tools of historical astronomers, tools students and amateur astronomers use today, and advanced technological tools used by experts in the field of astronomy.

5a. Egyptian Pyramids

Ancient people who studied the heavens came up with many clever, and often large, tools. Some of the earliest were the Egyptian astronomers. The most visible testaments to these ancient astronomers’ skill are the Egyptian pyramids, some of which were built to align with the star Thuban of the constellation Draco (the Dragon). Five thousand years ago, at the time of the pyramid builders, Thuban was the pole star. This is no longer so - our current North Star is Polaris - due to axial precession (the slow, continuous change in our rotational axis and orbital path, which occurs over a period of about 26,000 years).

The pyramids are aligned to within a tiny fraction of a degree of true north. The pyramids also show that ancient Egyptians connected objects in the heavens with concepts of life and death. Many pyramids have air shafts extending outward from the tombs, pointing up toward the circumpolar stars, or stars that never set. For instance, the tomb of the Pharaoh Khufu, who ruled Egypt around 2550 BC, is in the largest of the Giza pyramids. In the 1960s, Muggle astronomers discovered that one of two shafts extending from his burial chamber points directly toward Thuban, whilst a second points toward the belt of Orion. Interviews of dubious veracity arise from time to time about the ghosts of the Egyptians buried in these tombs. Supposedly, as the interviews go, the ‘Immortal’ stars that never set put an enchantment on these men and women that made them want to stay in the world of the living, and therefore remain on Earth as ghosts.

5b. Stonehenge

Stonehenge is another fascinating work site of ancient astronomers. Sometime around 2600 BCE, ancient people in what is close to modern Salisbury, England, erected the famous, enormous, stone structure. Muggles have wondered for centuries about how early people were able to move such large stones, although wizards will be certain it was a simple levitating spell. The Stonehenge structure particularly aligns with the equinoxes, and possibly with other important solar and lunar events. Due to its astronomical alignment, Stonehenge marked an important meeting place of ancient witches and wizards, many of whom believed that magic was strongest on the longest and shortest days of the year. It once was believed that a strong spell-caster at Stonehenge during the summer solstice could bring a deceased person back to life, although modern magical theory tells us this is impossible. Even Muggles can feel the magical presence about the place, and they flock in large numbers to Stonehenge each summer solstice. Witches and wizards make the pilgrimage, as well, surreptitiously casting charms and brewing potions in the hope that their effects will be stronger at Stonehenge than at any other place.

5c. Early Tools

Although there are many other examples, historical astronomers did not always use such large-scale tools to study the sky. One of the most simplistic and widespread astronomical tools is the sundial. Most sundials use a small rod or bar to cast a shadow onto a flat plate. The shadow determines the time of day. Due to the tight association between the passage of time and heavenly bodies, many early tools in astronomy were calendars and clocks.

Another more sophisticated tool of historical invention is the astrolabe – an inclinometre that functions as a sort of astronomical computer. Not only does an astrolabe tell the time and date, but it can also predict the locations of the Sun, Moon, planets, and stars; triangulate locations; and be used for astrological predictions. A related tool used for many of the same functions is an armillary sphere, which consists of a series of rings that represent longitude, latitude, the ecliptic, and other important orientations of the Earth in space. Due to the non-electronic nature of these tools, some witches and wizards still use or wear astrolabes and armillary spheres, confident that magic will not warp their predictions.

5d. Telescopes

These ancient tools lead up to the basis of all modern astronomy: the telescope. The first telescope was built by Muggle astronomer Hans Lippershey, in 1608. However, the introduction of this tool into the wizarding community is credited to Galileo Galilei. Galileo was a Squib born to a prominent Italian wizarding family in the 16th century. Jealous of his magical younger siblings and relatives, Galileo strove to develop his scientific skill and attended a Muggle university. When he heard about Lippershey’s telescope, he seized the opportunity to develop Muggle science into something useful for wizards. He improved the design of the telescope so it could magnify objects to a much greater degree, allowing it to be used to observe heavenly bodies. He began to sell these improved tools to wizards and Muggles alike, which made for an unusual overlap of such historically separate communities. Galileo began to collect data about the Moon, planets, and stars, and was respected in both Muggle and wizarding circles, until he was accused of heresy for declaring that the Earth orbited around the Sun. Nonetheless, Galileo’s contributions are still important, and his telescope is a tool with which witches and wizards interested in astronomy should become familiar.

Although more advanced telescopes are available, witches and wizards below the O.W.L. level of astronomical study will use a simple optical telescope as their primary tool. We refer to these telescopes as ‘optical’ because they collect light in the visible spectrum. At higher levels of study, you may look at light in other parts of the electromagnetic spectrum, as well. Not only are optical telescopes easy to use, but their purely mechanical nature also allows them to be used at places with high concentrations of magical activity, such as wizarding schools and dense magical communities, where electronic tools and computers may not operate.

5e. Two Basic Types of Optical Telescopes

There are two basic types of optical telescopes: refracting and reflecting. A refracting telescope uses lenses to collect and focus light – this is what Galileo built. You also may encounter reflecting telescopes, which use curved mirrors instead of lenses to gather light. The primary mirror, which collects the light, reflects it to a secondary mirror in front of the first, which reflects the light to the eyepiece so you can observe it. Students should purchase a small refracting or reflecting telescope for their observations.

There are two important properties to keep in mind when working with different telescopes. The first is the light-collecting area. This simply refers to the amount of light the telescope can gather at one time. Because lenses and mirrors in telescopes are round, their light-collecting areas usually are described by their diametres – for example, a one-metre telescope. However, keep in mind that the area is proportional to the square of the diametre. Thus, a two-metre telescope has twice the diametre of a one-metre telescope, so it has two squared, or four, times the light-collecting area of the one-metre telescope.

The second important property of your telescope is its angular resolution. This is the smallest angle over which two dots are seen as distinct, rather than one blurred point of light. With the naked eye, without help of telescope or spell, the angular resolution of our eyes is about one arcminute. This means if two stars are closer together in the sky than one arcminute, we will not see them as separate points of light. Generally, larger telescopes will have a better, or smaller, angular resolution.

5f. Using Telescopes

To use your telescope, set it up in a dark location, free from light pollution and obstructions to your view. Hilltops and towers are particularly good places for observation. Use a tripod or other mount to hold your telescope steady whilst you observe. When you are ready to look at an object, look through the small finder on top of the telescope to locate your object of choice. The finder has a much wider range of view than the eyepiece of your telescope, which is what makes it helpful for picking out a particular object from the broad range of the sky. Once the object is in your field of view, look through the eyepiece. Adjust the focus until you see the object crisply, and observe it to your heart’s content. Note, however, that if you view the object for longer than a few seconds, you will have to follow it west as Earth’s rotation makes the object move across your field of view. If you are observing the Moon, your telescope will help you see the craters, mountains, and lunar maria on the Moon’s surface.

Though small telescopes like these are useful, their practicality has its limits. The main limit of astronomical observation from the ground is the Earth’s atmosphere. The molecules of the atmosphere are moving constantly, the technical term for which is turbulence. Turbulence causes stars to appear to ‘twinkle’ in the sky, as they appear to move back and forth. Additionally, not all light makes it to the Earth’s surface because some wavelengths are blocked by Earth’s atmosphere. Muggles have learnt to solve this problem by sending large telescopes into orbit around Earth above the atmosphere, such as the Hubble Space Telescope. Some wizard astronomers choose to take this route as well, sending their telescopes into space with strong levitation spells. (Wizard satellites also are enhanced with powerful cloaking and repelling charms, for obvious reasons.) Another solution is adaptive optics, which help telescopes account for the turbulence and counteract it. Muggles use computer programs for adaptive optics. Electronics-savvy wizards may use computers, or they may enchant the mirrors of their telescopes to move the opposite direction of the air currents. Pre-enchanted telescopes are available for sale, but the buyer will be out a large number of Galleons.

5g. Other Types of Telescopes

So far, we have only discussed visible-light telescopes. However, there are telescopes made to observe every type of light in the electromagnetic spectrum. This is important, because objects in space emit light across the spectrum, and observing other kinds of light can help us learn much more about space objects than visible light will. As radio waves have the longest wavelengths, radio telescopes must be quite large. Unfortunately, radio-wave pollution is an even bigger impairment to observation than visible-light pollution, which makes radio astronomy difficult. Infrared and ultraviolet telescopes, due to their similar wavelengths to visible light, look very similar to visible-light telescopes.

X-rays are an even more difficult problem. Because x-rays have high energy, they go right through most materials, including the mirrors used for lower-energy light telescopes. X-ray telescopes require grazing incident mirrors, which are designed such that x-rays only graze the surface instead of passing through. Gamma rays, which have even higher energy, pass through even grazing incident mirrors. Large detectors are necessary to gain information about gamma-ray photons. However, introductory students will not be exposed to these types of telescopes.