The video, presented on the CrashCourse channel, is another issue of short lectures on astronomy. The issue under consideration is almost entirely devoted to such an essential object in astronomy as a telescope. The video is divided into several parts, explaining how exactly telescopes work, looking at the disadvantages and advantages of two types of telescopes – refractors and reflectors – and explaining modern technology and physical processes (CrashCourse). Each of the topics is described in detail using specific examples and simple images to facilitate understanding.
First of all, the presenter, Phil Plait, explains the most basic concept associated with telescopes – their purpose. Contrary to popular misconception, telescopes are not designed to simply magnify distant objects. Instead, telescopes make the recognition of space objects easier, make invisible things visible, and those that are already visible more clearly noticeable (CrashCourse). These targets are possible because the main task of the telescope is to collect light. While the human pupil collects a small amount of light, lenses or mirrors used in telescopes can collect, redirect, and focus light to make even the dimmest objects visible. In this case, the most important is the resolution, which makes it possible to distinguish between two separate adjacent objects, rather than simply the ability to magnify.
While the first telescopes were made with lenses, mirrors are now actively used. This transition allowed us to get rid of several problems at once. First, lenses are challenging to use because they flip and invert the image, making it difficult for human perception. Second, astronomy’s growing needs require the manufacture of large objectives, and the manufacture of large-diameter lenses is a highly problematic task (CrashCourse). Simultaneously, mirrors are devoid of these problems; they need to be polished only on one side, while the other side can be used as support. Considering the advantages of different telescopes, the video author also advises on choosing a particular telescope.
Finally, the third discussed topic is the use of modern technologies for better observation of objects. The human eye sees in a highly narrow spectrum, while telescopes can detect other radio frequencies, such as infrared and ultraviolet radiation (CrashCourse). Thanks to the development of technologies, including digital ones, a person can actively accumulate information and quickly process it, thereby gaining more and more knowledge about the world around him every day.
Work Cited
“Telescopes: Crash Course Astronomy #6.” YouTube, uploaded by CrashCourse, 2015, Web.