Global Live Broadcasting of Solar Eclipses via the Internet: Innovative Use of the Internet in Astronomical Education

Masami OKYUDO <>
Misato Observatory

Asako ITAGAKI <>

Noritsugu TAKAHASHI <>
Meisei University

Eiichi WADA <>
Tomokazu MORI <>
LIVE!ECLIPSE Executive Committee

Masaya NAKAYAMA <>
University of Tokyo

Hiroki KONDO <>
Saga University


Total and annular solar eclipses are phenomena in which the sun, the moon, and an observer are located on a straight line. These solar eclipses are very dramatic events that give strong impressions to the observer, inspire interest in astronomy, and often motivate school students to study astronomy.
As such, solar eclipses are good phenomena as teaching material for astronomy classes. Students can learn the mechanics of the sun, the moon, and the earth by observing a solar eclipse.

Although it occurs once or twice a year, few people can observe the phenomenon, because each eclipse is visible in only a small geographical area. If students watch these eclipses in the classroom, a teacher has a vital tool for the teaching of astronomy.

We did a live broadcast on the Internet of solar eclipses for educational purposes. We have done five broadcasts since the total solar eclipse of Mongolia and Siberia in March 1997.

At the annular solar eclipse in Australia in February 1999, we had an experimental lesson in a Japanese junior high school. Students in the school watched the real-time video stream from Australia with much interest. Students learned details of the solar eclipse with real-time observation. We evaluated the lesson by questionnaire and found that real-time video is effective for astronomy education.

At the total solar eclipse in Europe and the Middle East in August, 1999, we broadcast a real-time video stream from several observation sites. The video streams from the sites were mixed into one video stream so that people watching via the Internet could understand how the shape of the sun differs depending on the observation site and how the shape deforms with the progress of time.

A lot of people watched the latest broadcasting. Our server computers received over 14 million requests from more than 120 countries. We could confirm the power of the Internet in the field of astronomical education with two directions. One is in how deeply the live broadcasting moves people and the other is in the number of people whom the broadcasting can touch.

Keywords: Astronomical education, Live broadcasting, Solar eclipse


1. Introduction

In the universe, the scale of space and time is very large. Therefore, it is important in not only the viewpoint of the science education but also in the point of personality formation that children learn about astronomy. However, many of the celestial bodies can be observed only at nighttime. Therefore, the classroom in daytime can use only textbooks, which are not as interesting as real events. Of course, using celestial phenomena that can be observed in daytime is one solution. One example might be a solar eclipse.

The solar eclipse is a phenomenon in which the sun, the moon, and the earth are on a straight line. Therefore, studying the solar eclipse has an important meaning for knowing the position and the movement of these familiar celestial bodies. Moreover, there are comparatively a lot of chances to study a solar eclipse because there is usually a solar eclipse about twice a year. However, solar eclipses cannot be observed from everywhere on earth. Especially with the total solar eclipse and the annular eclipse, in which the moon is completely located in front of the sun, viewing can be done only in a narrow region. However, if the image can be forwarded from the observation site to the classroom using the Internet, the solar eclipse can be observed from anywhere. Beauty and the dramatic changes of a total solar eclipse or annular eclipse give people a big impression.

We wanted to show the impression of the solar eclipse to people all over the world, and we expected that, as a result, people's interest in the universe would increase. We concentrated the volunteers and formed the LIVE! ECLIPSE executive committee in January, 1997. Since then, we have performed five live broadcasts of solar eclipses using the Internet between March 1997 and August 1999.

In this paper, first of all, we want to introduce the outline of these five broadcasts. And we report on the evaluation experiment done at two recent broadcasts (February and August 1999). We want to discuss the effect and the influence that the broadcasts have had on astronomy education.

2. Five live broadcasts

Up to now, we have relayed the solar eclipse of five times in total. Table 1 shows various data of each live broadcast.

Table 1. Summary of our five live broadcasts between 1997 and 1999.
Date 97/03/09 98/02/26 98/08/22 99/02/16 99/08/11
Total or Annular Total Total Annular Annular Total
Observing Sites Siberia
Australia Europe
Middle East
No. of Sites Stream 1
Still 22
Stream 2 Stream 1
Still 1
Stream 1 Stream 9
Transmission Line between Observing Sites and Tokyo NOC Satellite
Telephone Satellite Analog TV (Malaysia)
ISDN Satellite
No. of Web Servers 4 5 9 12 15
No. of Accesses (millions of hits/day) 1.7 2.3 1.6 2.2 14.0
No. of Access Countries 50 90 42 60 120
Streaming Technology NVAT PipeCam Real
Real Real
No. of Streaming Accesses (thousands of streams) 30(NVAT) 22 N/A N/A 160

2-1. "LIVE! ECLIPSE 97", live from Siberia on March 9, 1997

Live transmission was planed from 23 locations: Siberia (Shilka), Mongolia, and 21 sites in Japan viewing a partial eclipse. We succeeded in transmitting from 19 sites, though Mongolia and a few sites in Japan were closed because of bad weather. It was the world's first simultaneous Internet live broadcast of a solar eclipse relayed from various locations. Broadcasts of movie images from Shilka were done using the NVAT system sponsored by NEC. Transmission of that movie data from Siberia to Japan was done using INMARSAT satellite. Transmission of regular images (JPEG format) from other sites was done using telephone lines.

Figure 1. Screen shot of live broadcasting "LIVE! ECLIPSE 97" on March 9,1997. The upper right image is a solar eclipse image of Siberia in which NVAT was used. Images of the partial eclipse below are all ones taken in Japan.

2-2. "LIVE! ECLIPSE 98" live from Venezuela on February 26, 1998

Movie images of the total solar eclipse were relayed from Venezuela (Maracaibo) and Guadeloupe, a Caribbean island. Used for this broadcasting was a PipeCam sponsored by Netspace and Hitachi, Ltd. We relayed images to the network operation center (NOC) in Japan using international telephone lines. The images were relayed to other servers that were set up in Japan and other countries, by which the images were retransmitted all over the world. We learned from the experience of LIVE! ECLIPSE 97 that the servers for broadcasting must be placed away from the observation site and that the Internet is not a stable way to transmit data.

The reason why our live transmission succeeded, unlike some similar events, which failed [1], was that we didn't use the Internet for sending data. We sent them directly from Venezuela, where the network traffic jam was very terrible, to Japan. This method was used for all of our projects after that.

2-3. "LIVE! ECLIPSE 98 Annular" live from Malaysia on August 22, 1998

Movie and still images of the annular eclipse were relayed from Pulau Dayang, Malaysia, and still images of the partial eclipse from Okinawa, Japan. Video images from Pulau Dayang were sent to the NOC at Nihon University Center of Information Networking via two satellites under the cooperation of Binariang Co., a Malaysian communication satellite company. Then they were encoded to RealVideo, and delivered from a J-Stream server.

2-4. "LIVE! ECLIPSE 99 Annular" live from Australia on February 16, 1999

We provided the coverage of the final annular solar eclipse in this century from Mullewa in western Australia. We provided the multistage coverage by encoding RealVideo, transmitting to J-Stream over international telephone lines (ISDN 128Kbps), and then distributing the moving images to other Internet service providers (ISPs). In addition, we had some first attempts: for example, experimental classes in three Japanese junior high schools using the Internet coverage as a subject matter, and the live voice reports of the local staffs.

2-5. "LIVE! ECLIPSE 99" live from Europe and the Middle East on August 11, 1999

We provided this coverage from nine points between England and Iran for about three hours on August 11.

The images of the sun taken at all the viewing locations were digitized locally and transmitted to the Japanese NOC over the Internet. The NOC converted the digital signals back into video pictures, editing them comprehensively by the video processing unit. They were digitized again and retransmitted to the Internet via ISPs. These video data were received by the users. From nine locations spanning England to Iran, we succeeded in transmitting corona images from six locations, centered in the East.

Unfortunately, the other three sites could not send corona images because of bad weather. Through our system of combining images from different locations into one screen it was possible to view the gradual progression of the shadow from west to east. During this eclipse our home page had 14 million hits from over 120 countries.

Figure 2. Screen shots of live broadcast "LIVE! ECLIPSE 99" on August 11, 1999. We synthesized flexibly one to nine images from different sites into one screen.

Figure 3. Video transmission system of "LIVE! ECLIPSE 99."

3. Evaluation experiment

3-1. Remote class lesson in junior high schools

In an Australian solar eclipse on February 16, 1999, we did a class lesson using the Internet broadcast at a Japanese junior high school. The purpose was to examine whether the students' understanding of a solar eclipse increases from observing the Internet broadcast and whether their interest in the field of astronomy improves. At the same time, we prepared teaching material to make good use of animation on the website and compared the teaching material with the usual teaching material.

The time difference between the observation site and the classroom was one hour. However, because the time of the solar eclipse was after school, we were not able to do the evaluation during usual class time. Kamegawa junior high school of Kainan-City (113 students), Misato junior high school of Misato-Town (22 students), and Hase-Kebara junior high school of Misato-Town (13 students) participated in this experiment. As for the first grade and the second grade students of Kamegawa junior high school, all members participated in most. Only the applicant participated in other students.

The flow of the class is as follows.

  1. The questionnaire on interest in astronomy and understanding of solar eclipses is given to the students before they watch the broadcast.
  2. The class is instructed: "Let's see the live broadcast of the solar eclipse which is happening in Australia now."
  3. Because it takes awhile for a partial solar eclipse to become visible, the students study solar eclipses by using the tutorial text of "What is the solar eclipse?" on the website while they wait.
  4. The students pay attention to the screen when annular eclipse approaches.
  5. When the annular eclipse ends, the students answer the questionnaire again.

What should be mentioned especially from the results of the questionnaire is as follows.

  1. The number of students interested in an astronomical field was 38 percent before this experiment.
  2. The number of students who correctly knew the arrangement of the celestial body at the solar eclipse was 72 percent before this experiment.
  3. Eighty-four percent of the students understood the explanation that used animation.
  4. Fifty-four percent of students understood solar eclipses from the traditional textbook explanation.
  5. Seventy-six percent of the students felt that this broadcast was useful for their understanding of the solar eclipse.
  6. The students' interest in astronomy rose after this broadcast: 60 percent indicated an interest after watching the eclipse.

3-2. Reaction of the general citizens

In the solar eclipse relay of August 1999, an easy questionnaire survey was done on two places (a Japanese page and an English page) on the website to see whether the viewers' interest concerning astronomical phenomena was improved by seeing this broadcast.

In this solar eclipse, the experiment in schools was difficult because of the summer vacation. Therefore, we did the questionnaire intended for general citizens. The effect of only seeing the broadcast without using the curriculum that had been used in the junior high school was evaluated. First, we asked respondents what kind of access line they used, their job, their age, etc., as basic demographic information. Then the questionnaire asked whether their interest concerning astronomical phenomena had increased by seeing this broadcast.

In the end, 899 answers on a Japanese page and 3,621 answers on an English page were collected. Most of the viewers were in their 20s and 30s, and many were company members and students. Most of the respondents said they accessed the server with a modem. The ratio of access numbers on a Japanese page and an English page was 1:4. Therefore, the ratio of those answering the questionnaire can also be assumed to be 1:4. After having seen this broadcast, 57 percent of respondents reported improved concern for astronomy phenomena: 69 percent of those who answered on a Japanese page, and 55 percent of those who answer on an English page. We think this result could indicate a difference between Japanese and foreigners.

4. Results and discussion

In our five solar eclipse broadcasts, we have told the phenomenon of solar eclipse to a lot of viewers all over the world. We have accumulated the knowledge of relay technology every time.

Our server came to receive 14 million hits in only a day in the last solar eclipse. Our knowledge of how to process a huge number of accesses is sure to be important in the dealing with the confusion of the information network generated by a disaster. We want to present this matter separately by the theme of research of the decentralized processing technology at a high load.

Moreover, we have achieved the technology of synthesizing the data from many points into one broadcasting screen and transmitting it cheaply by combining existing systems. This knowledge will be applied in scenarios in which a lot of multipoint relays are needed. We want to introduce this matter in detail again.

In this paper, we gave priority to the experimental broadcast of the solar eclipse to gauge the effect of the education being brought to the viewer. In the website questionnaire for not only the school education but also the general public, which will be needed more and more in the future, a lot of data were acquired. We learned that 60 percent of audiences feel that their interest for astronomical phenomena increased after watching the live broadcast of the solar eclipse. Our project's purpose of making many people feel the emotion of the eclipse and increasing their interest in astronomy was mostly achieved.

Because most celestial phenomena occur at night, many astronomy classes, to enhance their education, conduct nighttime observations. Some groups try to use the Internet to watch stars during daytime through a telescope on the other side of the earth, where it is night. For example, the experiment of a remote-controlled telescope is done in some groups of the world, and Misato Observatory is compiling a lot of operation practice in Japan [2]. In the future, we want to combine an irregular broadcasting such as solar eclipses and daily remote-controlled telescopes with an astronomical database, etc., and establish them as an overall curriculum that uses the Internet.

When we executed these five solar eclipse broadcasts, the support of a lot of volunteers and enterprises and groups was received. Moreover, we received much cooperation from Ms. Hitomi Ohara, BELLSYSTEM24 Inc. in the data work on the questionnaire. We would like to thank them.


  1. Goldman, Stuart. J., "The Eclipse and Weblock," Sky & Telescope Vol. 95,No. 5, p. 61, (1998).
  2. Okyudo, Masami, "Educational Activities Using the Internet at Misato Observatory," Proc. of the Misato International Symposium 1998 on Astronomical Education with the Internet, pp. 61-66 (1998)