Astronomy Videos on YouTube

Astronomy is uniquely suited to video, thanks to the visual beauty of celestial objects and the dynamic nature of many phenomena. National media producers like PBS/NOVA and National Geographic have long filmed videos for television broadcast, but the Web has allowed anyone to create and share astronomy videos with large audiences. YouTube channels such as SciShow Space, Kurzgesagt and the Crash Course series all feature popular astronomy content. These channels have also attracted viewers who have created their own astronomy-themed videos, including tutorials on how to operate telescopes and tips for astrophotography.

YouTube’s astronomy creators range from expert astrophysicists to amateur astrophotography hobbyists, and everyone in between. They create videos to answer questions from curious amateurs and lifelong learners alike, and their topics cover a wide variety of subjects. Some are more suited for the casual viewer, while others are designed to support students in a formal astronomy class or those learning through a massive open online class, or MOOC (also known as a “MOOC”).

The Teach Astronomy channel on YouTube features short videos that are usually about 15 minutes long. They were originally filmed as lectures for free-choice adult learners in a MOOC but are available on YouTube so that they can be watched outside the context of a course. Weekly viewership and viewer retention patterns for these videos are documented in Figure 6. Viewership spiked during the COVID-19 pandemic, and has yet to return to pre-pandemic levels.

Most of the videos on the Teach Astronomy channel have few views, with most having only a few hundred views. The most popular videos include those on adaptive optics, the Jovian planets and astrophysics. The most popular of the other twenty videos is about compact stellar objects (Chandrasekhar limit, Schwarzschild radius and degenerate matter), reflecting the public fascination with exotic end states of stars.

There was a significant spike in impressions of the channel during the week of April 28, 2019. Impressions are the number of times a video thumbnail appears on the YouTube website before it is clicked to be viewed. This week saw a total of 32,844 impressions, compared to the normal range of 900-4,000 per week.

The average amount of time per video viewed on the Teach Astronomy channel is also very low, indicating that most videos are not being watched in their entirety by most viewers. This finding is consistent with the overall viewing habits of most people using YouTube, who typically watch a few seconds to a few minutes of a video before moving on. Consequently, the popularity of these videos is not likely to be sustained unless more of them are screened in-person and/or are linked to by other websites with high traffic. This study suggests that astronomy creators should focus on creating videos that are a good fit for the viewing habits of YouTube users and consider other ways to reach the broader astronomy audience. This could include filming a video “talking glossary” of astronomy terms and delivering it by verbal request through smart speakers such as those sold by Amazon and Google.